Random Bot

ViewSonic VX2235wm and ADSL issues

2011-09-15T18:48:00.000-07:00

I know this is a true story because it happened to me.

On a non robot slant I got to do some consumer electronics repairs recently. I have a 22" wide screen monitor on my main desktop, a ViewSonic VX2235wm. The desktop is five plus years old but still working well and more than enough of the odd internet cruising and mplab activities. The hard drive was starting to throw bad sectors so we decided to upgrade the machine to Windows 7 and replace the old hard drive. The wife installed Windows 7 fine. Everything was going along fine until we tried to access the internet. No joy. The Netgear ADSL wireless modem would drop it's internet connection whenever this desktop was on. Booting back to the XP setup, same issue. We also remembered the last time this desktop was on the laptop lost internet connection, but previously things had been fine.

We found that when the desktop goes on, 30 seconds later the internet connection gets dropped. Desktop goes off, internet come back. Wacky power issues?

Then I triggered it wasn't when the desktop came on, it was when the monitor came on. After replacing power cables things still weren't working. Different power circuits, still the same issue. We ran an extension lead from the 15Amp circuit in the shed, same issue. In all this time the monitor was working fine. The picture was fine, no odd behaviour.

Powering down the monitor and trawling the internet the wife found this monitor suffered from the common "bad capacitor" issue. Various electronics components get made with substandard capacitors which leak, fail, etc well before they are expected to. Based on what we were reading the wife suggested that I try and fix the monitor. At first I was reluctant to take apart a working monitor in case I made the issue worse and would be unable to fix it. However as the wife pointed out the monitor was useless as we lost the internet connection every time we turned it on. To the shed.

Taking apart the monitor was easier than expected. A few screw and then some gentle prying with a flat tip screw driver popped off the case. I didn't even break any of the snap together lugs. My daughter helped out by poking things with a screwdriver. A few more screws and the power supply circuit board was accessible. Three seconds later it was obvious what the issue was. The 400V 120uF capacitor had a nice blob of black goo coming out of it. Without that capacitor a large amount of electrical noise would be going back into the power line. This noise was so great it caused the ADSL modem to lose sync. Glad I've already had kids.

400V capacitors aren't stocked by the normal hobby electronics stores I go to like Jaycar, etc. Instead I went online to RS Components for the part, mainly as they were offering free shipping. $8 and a week and half later I had the replacement part. Out the old and in with the new. After putting the case back together I did a smoke test and the smoke stayed in. Taking the monitor back inside and turning it on, success! No more drop outs of the ADSL line. Happy days again. Now the wife can finish setting up the rebuilt desktop.

I can't see how electronic repair shops stay in business. For even a simple job like this the time cost alone would be the price of a new monitor. So next time you need a monitor check the skip bins. An hour, a soldering iron and some capaciors later you might have a working monitor.

Mini projects II

2011-09-14T21:16:00.000-07:00

5 LEDs ready to shine

When you don't have time to do a real project you make up one. While doing some microcontroller tests I was using four separate LEDs. This was a bit messy with all the current limiting resistors. What would be better would be a small set of LEDs with resistors in one handy single block.

Ideally I wanted to use a SIL resistor array but didn't have anyone selling them locally (Little Bird Electronics now do). So it was going to be individual resistors and 3mm LEDs and some tight soldering. Also I wanted long header pins but no luck. Of course 3 days after I had finished Little Bird Electronics started selling long header pins.

My breadboard has two rows of holes above and below the normal breadboard area (ie for power rails). These power rail blocks have five hole groupings (instead of a continuous row of holes) so my LED stack would be five pins wide. That way I could plug in the block of LEDs into either the positive or ground rail depending on the circuit. As I am normally running 5 volts on my breadboard I used ?? resistors to limit the current to the LEDs.

The base for the project was a cut down piece of prototype board. Some tight soldering of header pins, LED, resistors and everything was done. I also had to file down the solder on the LED and resistor pins as the normal size header pins meant there wasn't much room underneath to ensure a good fit into the breadboard. Now the 5 bit loving can began.

Mini projects I

2011-09-11T23:21:00.000-07:00

Prototype board chop shop

For the last couple of months I've been working on a large dollhouse for my daughter so work on electronics stuff has pretty much halted. However I did slip in a few quick mini projects. One was a test circuit for hobby servos.

On my long list of things to try is controlling servos with a microcontroller (via assembly language). Before I started that I wanted some way of testing the various servos I have. All are bargain bin buys or salvage so I didn't have a high degree of confidence in them working. I didn't want to be banging my head against the wall debugging assembly language when the issue was with the servo.

So I did a quick internet tour and found a simple servo control circuit based on the 555 chip. (http://sarconastic.tripod.com/servodriver.html) . The site had an excellent guide to the operation and troubleshooting of the circuit. Hats off to that.

I setup the circuit on my baby green breadboard first. Hooked up the first servo and success! Servo go up, servo go down. The daughter loved playing with it to the point that the pins on the 10K pot used were almost snapped off. I did have one servo fail as it only moved a few degrees and stopped. However after taking the servo apart I remembered many years ago I had modified this servo to do continuous rotation (ie not a server, just a gearhead motor really). The passage of time...

The breadboard was cramped and messy so I decided to do the project properly (and to be honest just wanted to do a little project so I feel like I'm making progress). Since the circuit was just a 555 chip and some associated components I used a small prototype board which I cut down to size to fit in the small project box I was going to use. I used molex connectors for the servo and power plugs to be attached to. I considered having the batteries inside the project box (using a 9V battery with a 7805 regulator) but decided that since this test box would get very little use having batteries slowed discharge and leak was a bit of a waste. Also the self tapping screws used in the project box would only strip out over time. So external power was the go. The only other external part was the 10K pot used to adjust the servo position.

To support the two molex connectors (a 3 pin for the servo, a 2 pin for power) I glued a scrap piece of prototype board to the underside of the lid of the project box. I used a step drill bit to drill out the hole for the 10k pot. An hour of soldering later everything was almost working well. The prototype board I had used under the molex connectors needed a bit of probing as the glue had meant the solder didn't connect to the molex pins very well. A bit more heat and solder solved that.

Again the self tapping screws of the project box were a pain. Soft, poor quality metal screw heads.

Varbox circuit diagram

2011-05-03T17:45:00.000-07:00

Created with TinyCAD and exported as a png file

Variable resistor box

2011-04-20T20:54:00.000-07:00

Point to point wiring - yummy

While playing around with a current microcontroller project I found myself constantly swapping around the same resistor for a few different valued resistors. This led me down the path of wishing I had something to plug into a circuit that could change the resistor value easily.

I had seen resistor wheels before but they usually only had a limited range and were at the standard set resistor values. In essence a multipole switch. I wanted variable resistors. I had seen a project that had five variable resistors linked in series (not sure where I saw this, lost in the internet haze). The resistor values started at 1K and jumped up in value (10K, 50K, 100K, etc). That was closer to what I wanted. But I knew that variable resistors all have a tolerance range so it would be better to bypass the variable resistors I didn't want to use. It also meant I could set one variable resistor to a value, switch it out, set another and toggle between the two. Great for 555 timer circuits for example.

So I wanted half a dozen or so variable resistors in series with switches attached so I could bypass any variable resistor as desired. For values I chose 1K, 1K, 10K, 50K, 50K, 1M. The first 1K was a 25 turn precision type. The rest were the single turn type. Originally I was going to use a 100K resistor as the fifth resistor in series but the store was sold out so I went for another 50K resistor. I used SPDT switch to bypass the resistors. Finally I used a 2 pin molex connector to attach my test leads to. I would make up a few test leads with different ends (IC hook testing connectors, alligator clips, breadboard wire plugs).

To house everything I used a black UB5 jiffy box. It was the smallest box that could fit all components on the lid with a reasonable spacing. All wiring was simple point to point. I had been waiting for a good project to try out my new soldering iron station too.

After a quick mud map sketch I created a proper schematic with TinyCAD. Five minutes later I'm all done. There is nothing hard with this circuit but I'm finding as I tend to only get short amounts of time to spend on projects spread across a long period of elapsed time so documentation is a must.

Since I would be cutting out 11 holes and 2 squareish slots from the UB5 box lid I created a drill template using CadStd. A lot of mucking around was involved as I remember how to use CadStd and finally I had a nice template. As I planned to use my milling machine to actually make the holes the template was more to make sure my measurements were right and provide some sanity while making cuts.

When I came to drill out the holes (both the variable resistor and switches have round shafts) I used a 3-12mm step drill. The light plastic of the UB5 box lid can't really handle having an 8mm drill (needed for the variable resistors) go through it in one hit. Plus the plastic was only a few mil thick so the step drill went through it very easily. The mill made making a straight line of holes dead easy. The quality difference over my $100 drill press in terms of chuck wobble and control makes me think my drill press is going to get pretty dusty. For the 25 turn resistor I drilled two small holes and then filed out the remainder to get a rectangular slot. If I had been really keen I could (should) have used the slot cutter. For the 2 pin molex connector I used a dremel to cut out some material so the header sat recessed slightly so the pins were accessible from the other side of the lid. Finally I used an off cut of prototype board to glue (with 2 part epoxy) under the 25 turn variable resistor and 2 pin header to provide some more support. I didn't want the 25 turn resistor to be pushed through the lid and I didn't think a bit of hot glue would hold it well enough.

When the glue was dry and after cleaning up the holes I mounted all the variable resistors and switches. Ah, straight lines of components. It really does make a difference. Next was an orgy of wiring stripping, tinning and point to point wiring. Lots of double checking for shorts along the way. Then the lid was screwed onto the UB5 box. This was when I found the only bit of this project that failed. The self tapping screws that came with the box were rubbish. The head of one stripped and another started to go. Cheap soft metal were used in the screws. Not happy Jan. Finally I make up some tester cables and printed out some labels.

The majority of the parts for this project came from Jaycar. No reason other than Jaycar is my closest store. The IC testing hooks and alligator clips came from http://www.dealextreme.com/.

Parts List

Jaycar parts

SPDT switches (ST0300)

Variable resistors (RP8510, RP8516, RP8524, RP8504, RT4644)

Dials (HK7734)

UB5 jiffy box (HB6013)

2 pin molex header (HM3402, HM3412)

Dealextreme parts

Electrical Wire Testing Hooks (10-Pack)

Multimeter Testing Clamps (10-Pack Small)

Pennybot

2011-02-22T20:35:00.000-08:00

Pennybot is my attempt at a second mini sumobot. A sumobot with brains (or at least a microcontroller), IR sensors to detect opponents and possibly other sensors (a front touch sensor looks like a good idea). Again I will be constructing the chassis mainly from scratch. For motors I had two GM2 motors from Solarbotics. I really liked the offset design of the motors and skinny wheels available. Getting Nudgebot to fit in 10x10cm box was quite a challenge with the standard Tamiya gearbox and wheels. The GM2 motors will make life much easier.

For the chassis I tried many ideas before getting it right. All were around the same concept with the motors mounted on pieces of 90 degree aluminium which in turn are connected to a base plate. Just the positioning and battery location kept changing as I kept finding flaws in the designs. Part of this was due to looking at the design over a few months rather than spending a whole day just to work things out.

In the end I mounted both engines on 80mm lengths of 90 degree aluminium angle. Due to the position of the holes in relation to each other I used a paper template rather than dead reckoning to position the holes. The end result was quite a nice job (compared to other jobs I've done).

For the base I used the Tamiya plastic base plate like I had used on Trackbot and Nudgebot. Pre spaced 3mm holes are wonderful.

I mounted the motors on the bottom of the aluminium angle in order to fit the batteries underneath the base plate. This put the batteries at the lowest point and ensured the centre of gravity was as low as possible. To stop the batteries being damaged or accidently falling out I made a cover plate from some thin metel sheet (The EMF covering from inside an old Sun unipack disk enclosure). Instead of bolting the cover plate to the base plate I used a 3mm tap to put a thread in the cover plate. This meant I didn't waste space by needing room for nuts. Another case of "why didn't I always do this". At least that tap and die set purchased was justified.

For batteries I am using 5 x AA batteries. The motors are rated at 6V so I'm still working out if I either over supply the motors, use a diode to drop the voltage or just make a separate 6V tap. I intend to use a LM2940 low voltage regulator to provide a 5V supply off the 7.5V from all the batteries. How this regulator handles the noise from the motors is to be determined.

I did a quick temporary solder to add a power switch and did some push tests with 4 batteries (6V). No issues pushing the necessary weight (500gm). However I am slightly concerned by the amount of wobble in the axle on the motors. Straight line driving is really needed but there was definitely some travel. Hopefully when I screw the wheels to the axles (rather than just push them on) this will tighten up the slop.

CadStd review

2011-02-21T21:45:00.000-08:00

Much in a similar vein to using TinyCad to produce semi professional schematics I decided to up the level of my designs with a CAD package. I needed something that was cheap, easy to learn/use and could produce 'true size' paper print outs. The dual end goals were to document my designs but more importantly be able to produce templates for machining (eg drilling templates). Previously I had used graph paper for these tasks.

I had no experience in using CAD packages or technical drawing. So the first step was some research into what a CAD package can do and what to expect out of one. I would recommend anyone looking for a CAD package do this first as some CAD programs are more focused on particular tasks than others (eg 2D vs 3D plans).

After some web research I came across CadStd (www.cadstd.com). The product has two versions, a free unlimited use lite version with some restricted functionality and a licensed pro version with full functionality. The lite version could be all that you need in cases where you are only doing simple plans. After using the lite version to do the tutorials I purchased the Pro version at $37.50 USD. The version I have is 3.7.2. CadStd is a 2D program but it does do isometric projections.

The install was simple with the total install size approx 5mb. There is a tutorial that runs through the basic functionality in a structured lesson format. By the end of the tutorial I was able to construct some simple plans. There is also a user guide. That said you will need to a few hours playing with all the drawing functions just to see how they work. I found some of them odd to begin with (like the three ways to draw an arc) but I suspect that is due to a lack of experience in both CAD and technical drawing. This is definitely a case of the more you do the easier to becomes. CadStd isn't MS Paint with a bit added. It's an engineering tool. You will have to work to use this but that seems to be constant across the CAD field. Feel free to insert "learning curve" in there too.

The litmus test was turning a technical drawing (the Solarbotics GM2 motor plan) into a drilling template. The drawing was detailed but not to scale. After an hour of fiddling I had drilling template ready for use. So success. Did I need the Pro version to do this? No. However I like to support people making tools like this.

I would recommend CadStd to anyone who has limited time to learn new products but is sick of using graph paper to make substandard templates. Be prepared to spend 2-3 hours to learn how to use it and expect to make so odd mistakes along the way. Ctrl-Z is your friend.

A(nother) headbot

2011-02-15T01:44:00.001-08:00

Another project coming out of "Junkbots, Bugbots & Bots on Wheels" was the construction of a headbot based on the 74AC240 'biocore'. Again I would fully recommend this book for it's interesting projects and "make stuff from junk" ethic. The biocore was constructed according to the instructions in the book. I used 22uF capacitors as suggested.

My first attempt at a base was a failure. I used a small 3-6V DC motor with a pulley attached, which was geared down (via a belt drive) to another pulley that was attached to a larger base plate which had the batteries, biocore, etc. In essence trying to simulate the book example of a cassette deck setup. However the balance was totally off and the motor would simply jam under load (or at best spin and the belt would slip). What I needed was either a cassette deck or a gear head motor. Frustrated I put the biocore and other parts back in the big box of components for another day.

A couple of years pass. Kids arrive. My soldering iron gets rusty.

One day at Dick Smith (when they still sold electronics) I purchased an old and heavily discounted line following robot kit fot $20. The design was poor and complicated but at tht price I wanted the parts. Two gear head motors, a relay, seven IR leds, etc. Bargain. Now I have a gear head motor.
The 74AC240 was purchased from Solarbotics. For the base I used the wheel from the above mentioned robot kit as that was keyed to fit the 4.5V gear head motor. The phototransistors were salvaged from an old balled computer mouse. The base plate is a lid from a vitamin container. While this lid was a great size it wasn't the best choice.

My power source was to be two 1.5 volt AA batteries. For balance I mounted these batteries in two separate battery holders on each side of the motor. I used two part epoxy glue to stick the holders to the lid. However once the glue had dried I found that the glue simply peeled off the lid/base plate. Vitamin lids were obviously made to be highly non stick to stop nasty molds, etc from attaching. So instead of glue I used small (2.5mm) self tapping screws to attach the battery holders to the base plate. The screws came from my collection of salvaged cdrom bits.

The power switch was a small SPDT switch I had which I mounted sideways into the rim of the base plate. Then all that was left was to wire the various components together and put in the biocore. I couldn't decide on a good way to attach the biocore to the base plate so I left is 'hanging' but held in place by the wiring. The wiring was made to be just long enough so there was enough tension to hold the biocore in place. Finally the two eye sensors were attached to the rim of the base plate with U-tack. I didn't want to permanently mount the eyes as I wanted to trial the best setup.

TinyCad review

2009-07-03T18:09:00.000-07:00

As my robots have progressed from being other people's designs to my own I decided it was time to start properly documenting the designs. While reverse engineering is always possible having a clear schematic makes referral much easier. Nudgebot was the first project where I considered it complex enough to invest the time in learning how to use a schematic/cad program.

Before I started the search I had a few requirements

free if possible. I'm just not doing this enough to justify the cost of software.
recent. No 15 year old dos programs running in a dos emulator.
ease of use over functionality. I have limited time to learn and use a software package. I don't see my designs ever being that esoteric so a simple program which is easy to use is better than the "greatest software package ever" (tm) which needs a full week course to learn.
a CAD program that feeds into a PCB generation program, and the PCB generation program produces industry standard layouts (ie layouts that I can send to a PCB manufacturer).

A quick canvas of the internet showed up plenty of likely candidates. Top of the list was the linux based gEDA package and the windows based TinyCad/Freepcb combo. Both were open source and free. TinyCad/Freepcb where GUI based, gEDA being a mix of CLI and GUI. Given the mixed OS environment I was running in and the fact both TinyCad and Freepcb ran fine under linux via wine I decided to give TinyCad/Freepcb a try.

As TinyCad is designed to a simple program there were no tutorials that I could find. However the in program help was a tutorial by proxy and covered enough to make getting started easy enough. The interface was extreme intuitive (always a mark of a successful interface design) and very clean. Simplicity of design with easy of use. A rare combination in freeware land. A quick summary...

The Pros

small install (5mb)
very intuitive and easy to use
good design checker (to pick up those human errors)
ability to generate netlists (in multiple formats include those used by Freepcb), parts lists and export designs as images.
very easy to create new components and add them to the component library
good support forum
runs on linux under wine

Now for the cons...

limited default library. A limited library of components (no 555 chip??). That is offset by the ease to make new components (which is going to be mandatory for most people).
default library could do with a clean up. Duplicates of some components in the different libraries.
resize of components all but broken. You can resize components quite easily. However once that is done they don't (unless you are very lucky) match up to the underlying component grid. This means you will connect components together, save a design, reload it and all those links will exist (ie lines joining components) but won't actually be connecting said components. The design checker will pick these up but the first time it happened it was a case of WTF. The moral here is never resize components. If you want one smaller/larger best to create anew component of the desired size. It's annoying the first time but after you are aware of the problem I don't see it as a major issue.

Summary

A good circuit schematic design tool which met and exceeded all my requirements. After taking half an hour to ready through the help I was making my first circuit without issue. Fell down the resize of components problem but a quick search on the forum resolved that issue. Within a few hours I had not only created a number of new components for the component library but had also completed the circuit design of Nudgebot. The end result was a semi professional looking schematic that I could put up on the web for others to enjoy.

Now to check out Freepcb...

nudgebot part 5

2009-02-05T01:12:00.000-08:00

Nudgebot front and rear

With the circuit complete the only item left to complete was the front shield/scoop. This would both protect the front circuits and sensors and be the scoop to push opponents. With the rest off the robot down I had under 1cm before I hit the 10cm length limit. This meant the scoop would be very steep. The angle end up being approx 80 degrees. So the scoop wouldn't be scooping under over robots but more of a battering shield.

Since I had weight to spare (nudgebot was under 300gm) I went for a heavier metal than what I used for the rear shield. I couldn't go to heavy otherwise I wouldn't be able to work it with the hand tools I have (no sheet metal bender I'm afraid). My standard way of bending sheet metal was to clamp it in a vice and using a small engineers hammer to work it over the bend.

My bottom attachment points were on the front sensor board. The top attachment points were one the front screw holes on the main board. I also wanted the shield to wrap around the front sides and curve over the top of the main board to protect the battery and sensor plugs.

This front sensor board was 7mm above the ground so I curved the bottom of the shield (rather than end in a straight edge) to reduce friction/potential for small bumps to be grabbed. While this seemed to work well I found I kept having scratch marks on the sumo ring. This was because a small part of the bottom of the shield was touching, not the entire bottom of the shield. This resulted in nudgebot bouncing as this one point would catch, scratch and then bounce up and repeat. Much bending and rebending of the bottom attachment points were attempted to fix this. In the end one of them broke off. Sheet metal can only be worked so much. So with only three attachment points the shield was still very rigid. I had learnt from the rear shield that having the metal under a slight amount of tension added a great deal of rigidity. Strangely enough after the bottom attachment point broke off the issue of the scratching from the bottom shield on the sumo ring went away and nudgebot was running with ease across the sumo ring. I cut my losses and stopped fiddling.

All that is left to do is maybe paint the front and rear shields black (to reduce IR detection) and add in some lead weights to get nudgebot up to the 500gm class weight limit.

nudgebot part 4

2009-02-05T00:53:00.000-08:00

The brain board

The brain board was connected to the main board by a custom built six pin connector. On the main board I cut up a standard 8 pin DIL socket so I had two 3 pin connectors. These then went next to each other on the main board. The six connectors were power/ground/left sensor/right sensor/right motor/left motor. On the brain board I used an extended 6 pin connector (cut down from a 12 pin connector) that was approx 1.5cm long. This was then soldered into the main board.

Bottom of the brain board

However the first one I used turned out to be too short once the AA batteries were installed (always measure with everything in place!). This caused a problem as when I unsoldered it a number of the copper tracks came off too. Thus the second header was not as securely connected. Over time this weakened quite a bit and in the end I had to reinforce the entire lot with a big glob of epoxy glue to stop it from falling apart. Given the choice again I would just use a standard molex connector or like.

The brain board consisted of the 556 and 393 chips and associated variable resistors/resistors/etc. I used a small board (approx a third the size of the main board) and even that gave me plenty of room. I changed the circuit slightly from the original breadboard design by adding variable resistors to the time circuit in case it needed to make a few adjustments (in case my timings were off on the breadboard). After a few hours of careful soldering I was all done and ready for the first test.

Nudgebot read to go

Things started to look promising. Nudgebot drove well, detected the white line and turned, sometimes. Also there was a humming coming from the relays. Basically the relays were getting stuck (ie latching). The voltage would be at 3.5V approx and the relay wouldn't unlatch. This never happened on the breadboard design. After much trial and failure I did the obvious and used the 555 timer chip from the breadboard instead of the one I purchased for the brain board. Total success. Why were my two 556 timer chips so different? Well the issue was the design. When using a 555 to drive a relay you need a diode in series to prevent latch up. The book I had got the 555 design from specifically mentions it. I had just missed it and the breadboard 556 timer chip obviously handled this better than the other one. So I went with the breadboard 556 timer chip with a todo note for adding in the diodes in series when I get time.

With the bread board done the circuit was finished. Nudgebot worked great. It travelled well, detected the white line without issue, turned, etc. Only quibbles were the values I used for the variable resistors in the timing circuit were too high. At the lowest setting they triggered for approx 1 sec which with the motors resulted in a 100-160 degree turn. Fine but would be nice to have better control. Also as usual the motors performed differently with one motor slightly faster than the other and the turn being impacted by this. Again for a dumbbot this was fine. In fact the uneven turn meant that Nudgebot was unlikely to get stuck in a forward/reverse loop so it was kind of a blessing in disguise.

nudgebot part 3

2009-01-11T01:35:00.000-08:00

Nudgebot rear shield ready for abuse

Although sumobots aren't battlebots there is still going to be some wear and tear from bumps, falling off tables, etc. Looking at the rear section I thought there was a good chance that during bouts the motors cables might be damaged. So I decided to add a rear shield made out of light sheet metal to protect them.

The metal I used was from a Sun unipack disk enclosure. It originally was the shielding on the top of the disk enclosure. It is quite light but in the small size I was using and having it secured at four points it should be solid enough. I used some tin snips to cut out a rectangle of metal and then marked out the size of the bottom plate and cut at an angle to the top of the sheet. This was me trying to be fancy. I used a vice and small engineers hammer to work the metal into shape. Then I marked out and drilled the four attachment points (two top, two bottom). I had to be very careful with the drilling as even the 3mm drill would twist the sheet metal out of shape. Also on the top lip I had to cut out a recess around the components which I used tin snips to cut out. That was a bit rough so I should have used the cutting disk on my Dremel instead. A lesson learnt for when I get to making the front scoop and shield for the line sensors later on (and another reason I did the rear shield first - to work out all the things I shouldn't do).

Finally I will need to paint the rear shield (most likely black). Highly reflective sheet metal is light a flash light in the dark to infra-red detectors. Don't want nudgebot making things too easy for better sighted opponents.

nudgebot part 2

2009-01-10T01:36:00.000-08:00

Nudgebot engines and main board

Now with a reliable base it was time to start on the main base board. The first part to be done was mounting the 3V battery pack (2xAA batteries). This was mounted in the centre of the board. This was to keep the majority of the weight on the centre axis to imporve rotation of the bot. Once that was done I put in the two relays which will be used as the motor controllers. This was the same as trackbot. This setup has the advantage as it allows me to use 3 volt motors without needing to do dual power lines off one battery. Instead I have a regulated 5 volt line for all the circuit and plain "raw" 3 volts for the motors. This does mean I have two power supplies (9V and 3V). I used molex connectors for the engines as I knew I would be doing a lot of rework on the chassis so easy removal was a must.

Next was the 9V battery connector and the 5 volt power regulator. I used a 78L05 with various filtering capacitors. Rather than a power switch I used a two pin jumper as a switch. I also did the same for the 3V battery supply. This was to reduce not only space but also weight. Utility is much lower but I'm not seeing this bot being used every day.

With the 5V power supply available I setup the five second delay part of the circuit. This was formed from a resistor-capacitor circuit that was tuned to activate a relay and keep it powered for 5 seconds. This relay would be used to cut power to the rest of the circuit. Rather than have the circuit cut power to the logic chips (ie the 555 timer and sensor ciruits) instead I used the relay to cut power to the 3V power line. This was because the motor setup the motors are always on, either running in forward or reverse. These is no idle. So I needed to kill the motor power obviously. Also I setup the relay so that the NC would result in the circuit being connected. This way power drain is minimised. Some setups I have seen have the relay needing to be active (ie the NO pin completes the circuit) to complete the rest of the circuit. This always struck me as odd as it just drains the battery. Finally a small push button switch was added at the back of nudbebot to activate the time delay circuit. A quick test and everything worked fine. Hit the button and the motors cut out for approx 5.5 seconds.

Main board with the 5 second delay circuit on the right and the 5V power supply next to the 3v battery pack

I also did some push tests. The high torque gearing worked well with nudgebot being able to push 500gm without any issue. The only problem I can see is the wheels. They have a tread on them. Normally this is fine but in a pushing setup tread just means you don't have the maximum amount of wheel on the ground. Perhaps some sticky rubber bands will be added later.

was dumbbot, now nudgebot

2009-01-09T01:29:00.000-08:00

Nudgebot engine base

After some push test with dumbbot I found a few issues. First was some 'crabbing' by dumbbot. This was where the chassis would go sideways rather than straight ahead. This was due to the pulleys being pulled back at different angles. That was countered slightly but it was always going to be an issue as the axle mounts are quite loose.

I also found the power transfer from the motors wasn't great. There was a degree of belt slippage, but that was expected. However on the higher end of the push tests (ie .5kg dumbbot pushing .5kg opponent) there was very little pushing going on and a lot of belt slipping. I added some heat shink wrap on the engine shafts to try and reduce this but it was still an issue.

All these things together made me think that although the pulley drive system was cool it wasn't the best design. A sumobot that went sideways instead of straight that could barely push the 500gm weight wasn't good enough. Even those dumbbot was going to be an opponent I still wanted it to be up to standard. Thus a redesign was considered.

I needed a drive system that was solid and had the torque needed. The gearhead motors available to me were too long to sit side by side so I would have to have the axles at a 90 degree angle to the engine shafts. Annoying and hard to engineer properly. So I went back to my good friends at Tamiya and decided to use the dual gear motor set that I used for Trackbot. It fits well on the base plate obviously and was under 10cm wide. I used the lowest gearing ratio that gave 2276gf/cm and only did 38rpm. With two motors I should be able to push anything.

I used the same wheels but I sanded down the wheel hubs to reduce their width. I also cut the axles from approx 5cm to 4.7cm. Again this was to reduce the width so the engines plus wheels were under 10cm. With this extra work they were. A lot of grinding, cutting and fiddling around but the end result was a much better engine base. No point having a working circuit which is going to be let down in the pushing department.

Dumbbot pt1

2008-12-01T12:48:00.000-08:00

Dumbbot showing off it's motors

Dumbbot was designed to be my first Sumobot. Originally I had intended to construct a much more complex bot by decided that a simpler bot would be better as a first time sumobot. The project used various circuit "bits" that I had either used before or had seen.

Chassis

Not knowing how I was going to do the body construction I decided to make the base chassis the universal plate set from Tamiya. This plate is plastic, 6x?? cm and has been predrilled with 3mm holes. Being plastic it was easy to cut down to size (the magic Dremmel).

For wheels I chose the Tamiya tractor tires. Again being from the same range everything fits together. The 3mm hex axle was used. I did cut down the molding on the tire so it would sit closer to the body. This meant the width of the robot was now just under 10cm.

One of the hardest parts about a sumobot is meeting the restrictions on the size of the body (10x10cm - 500gm). To get two motors into a 10x10cm area is all but impossible with standard gearhead motors. The gearhead motors I used on Squarebot are 7cm long. So normally you need to be using motors with their drive shaft at 90 degrees to the motor body or some special gearhead motors where the gears are laid out to minimise the space used (like the Solarbotics motors).

I make a habit of pulling apart old cdrom drives for motors and gears. Luckily I had pulled apart two of the same model which meant I now had two motors of the same spec. These were approx 5cm long and rated to 9V. They weren't gearhead motors however. I needed a way to gear down the motors and connect them to the 3mm hex axles used to attach the wheels. Luckily Tamiya had something to help. They sell pulley set range consisting of various pulleys, gear wheels, etc. I used the 38mm pulley wheel on the tire axle and drove the other end of the system directly off the small (2mm) shaft of the motor. First I did some test to see if a pulley system would actually carry 500gm and also push 500gm. A few tins of mushrooms and tuna later and to my amazement the pulley system worked well pushing the 500gm tin with little issue. The only issue was the pulleys were too large for the axle and the base plate was in the way. So some more Dremmel work and I cut out some channels under the pulleys so they would run clear. I ran the motors at 3V as that produced a speed that seemed about right. The 3V power line came from 2 x AA batteries.

To attach the motors to the base plate I used some small scrap pieces of metal. I made a template of where the mounting holes were on the motor and used this to drill out the metal as required. One was good, the other needed a bit of filing to fit. Doing it again I would spend more time making the template. A bit of sheet metal work and I had custom engine mounts for my recycled motors.

On the opposite end of the chassis I had room for the 9V battery mount. This way the majority of the weight was as low as possible.

I intended to mount the circuit board above the engines and pulleys. So I used some 3mm screws and spacers to gain the height needed to mount the board.

Crabbot

2008-06-14T17:58:00.001-07:00

Crabbot

Crabbot is based on the same design as Rodbot. He was made for my six year old nephew who thought that robots were the coolest thing around and wanted one himself. So I wanted to make a simple and robust robot for him that could survive being handled by someone of that age. This meant no exposed componets and a solid body to survive a six year old grabbing it in a fit of exitement.

The LM386 chip was glued onto the body and a power switch was added to the front. All the wiring was kept as tight and clean as possible and I used heat shrink wrap to avoid any chance of little fingers touching bare wires. Finally I used a lid from a small gift box as the shell (hence the name Crabbot) to protect everything and to give my nephew something to grab hold of.

Crabbot exposed

The herbie design was great as the light tracking is simple and can be made more fun for a six year old by giving them a torch to "lead" the robot. I decided not to do the reverse sensor as the bump switch had a fair chance of being damaged.

The body used is a kit I purchased some time previously for use with Squareabout. However the interference from the engines to the rest of the circuit was so great I didn't use it. There are two 4.5V motors that drive three wheels each. The kit also came with legs that could be used instead of the wheels. I went with the wheels as they would work better on carpet.

Crabbot belly

Trackbot part 5

2008-06-05T04:02:00.000-07:00

Trailer for Trackbot

Once I had finished Trackbot I decided it would be good to have something to carry loads for Trackbot. Thus the Trackbot trailer was made.

The body was a body from a seven stacker CDROM drive. After a bit of trimming I had a nice flat tray to work with. The axle supports were plastic clips from some Cisco switch packing material. They looked like they could be useful and after a year of sitting on the shelf there were. The wheels/axle are Tamiya Truck tyres. I glued the axle supports to the body. I drilled a hole for the trailer to connect to Trackbot.

On Trackbot I made a trailer hookup from two automotive crimp connectors. In all the whole setup worked rather well. Only issues was in a sustained full reverse the trailer would jack knife, but that was expected.

Trackbot part 4

2008-06-03T15:42:00.000-07:00

Side shot of Trackbot

With everything together the first test drive took place. As with Squarebot much time was spent on getting the emitter circuit at 38kz (one day I'll buy a multimeter that does decent frequency measurement). However I was finding exactly the same issues as I did with Squarebot. Low range on the emitters and lots of noise, false detects everytime the motors changed direction, etc. Going back to the breadboard of the design I moved around some of the filtering capacitors on the power supply. Totally different (better) behaviour. Based on this I added a nice big 470uF capacitor to the main board on the power input plug from the power board. Totally got rid of all the electrical noise from the emitter circuit. So even short cables like those on Trackbot still result in large amounts of EMF. I really need to learn how to make my own printed boards.

Once the new filtering capacitor was in Trackbot worked beautifully. He avoided things, the bump switch worked fine and he could climb over anything. I did a bit more work on the programming to add the functionality that if both detectors detected something then that should be considered the same as if the bump switch triggered. Ie full reverse then turn to get out of trouble. With this simple response Trackbot has rarely gotten stuck on anything.

A few times I have mentioned size/weight issues of Trackbot and my attempts to reduce them. In the end Trackbot came in at 430gm. Most of that is engines and batteries. Rechargeable batteries I found weigh two to three times more than standard batteries too.

So what lessons did I learn from this design? That cables are bad and just add issues into a design is one. I am really impressed with the Tamiya education range. Precision plastic components all designed to fit together. Perfect for building bots out of and quite cheap too. Something else I learnt was that rechargeable batteries don't hold their charge over time. I few times I have given Trackbot a run after a month or so only to find the rechargeable batteries are dead but the standard 9V battery is fine. For the next design I need to consider moving to a more modern battery technology which is lighter. Also I should have put the bump switch on an interrupt pin of the microcontroller so that I could have seperate behaviours for the bump switch and when both detectors detected an object.

What do I want to do after Trackbot? Make a mini-sumobot. I have purchased some engines from Solarbotics and am current in deep thought mode of a design. What is taking up a fair bit of my time is how to design/make a chassis for such a small bot. A 10cm square isn't much room to get two engines and wheels into. Originally I considered using a small box and wedging everything into it. I had machined in the engines so that was looking good. However I found that getting the rest of the bot into a fixed container (PC boards, batteries) just wasn't going to work. No room to work with and a real pain to get at components (like batteries). So my thoughts now are to use multiple boards and stack them. Easy to design each board (one for motors, one for battery, etc) and they just screw together. All of this is on a bit of the back burner now since Sonja has arrived. But it's nice to have dreams.

Trackbot part 3

2008-06-02T17:58:00.001-07:00

Trackbot top shot showing main board

For the main board I used the same IR emitter/detector circuit used for Squarebot. I also added a PIC microcontroller to be the brains as I wanted a bit more that just avoidance in the design. All my original design work was done on a breadboard that stayed setup until the design was finished. I find this makes if very easy to go back and test things (like the flyback diodes described later) and when wiring up the boards it helps also. Also to push myself a little I used a PC board a third the size
of the board used for Squarebot. It was tight but worth the effort. The output from the detector circut went to the microcontroller. I also had a bump switch on the front of Trackbot as an input. The bump switch was mounted quite low in case an object was missed by the detectors and run into. The outputs from the microcontroller couldn't directly power the relays. Instead they switched a transistor which turned on the relays. I had also missed putting in a flyback diode over the relay contacts. As a result everytime the relays turned off a huge spike went through the circuit causing the IR detectors to "flutter" and false detect. Some small signal diodes fixed that, plus they fitted in the rather tight board as I hadn't originally allowed space for them.

The reason I choose a PIC microcontroller was primarily based on the programmer board I could buy. The board I purchased (details) was only $50 AUS and included a $9 microcontroller. There were few other cheap programmer boards available and not know how much I would be using it I didn't want to spend $300+ on a professional programmer to only use it once. For this project the PIC16F84 was more than adequate for what I wanted. Plenty of memory space and IO pins for my simple design. I had done some assember programming at Uni but I found an excellent PIC16F84 tutorial which meant I could get the most out of the chip with the least trial and error. The only other doco I used was the datasheet from Motorolla. The actual program will be in a later post. I did consider a DIY progarmmer board but didn't want the frustration of getting it working as most of the designs were very specific to certain computer hardware setups.

I found out a few things with the programmer/design. The first was that the watchdog reset was enabled by default. The result was the program was reset every few milliseconds. Strangely it wasn't till I was testing the bump switch that I noticed. The bump switch would send both motors into reverse for a short time then turn (ie one motor reverse). This was to get Trackbot out of the situation of hitting something full on and avoiding the "both detectors sense something, full reverse, nothing detected, full forward, repeat" situation. With the watchdog reset occuring this wasn't happening. The other thing that took some tinkering was the time delays on turning on the relays to control the turning of Trackbot. Since there is always a delay when a motor changes direction I needed to wait long enough for the motor have time to reverse and long enough for some actual "turning" to take place. This took a bit of trial and error as expected.

Next time the first test run...

Trackbot part 2

2008-05-04T01:25:00.000-07:00

Power supply/Motor drivers

On the same board as the motor driver I put the power supply. A simple design based around a 78L05 regulator. Again a smaller, lighter version of the 7805, but only rated to 100mA. Various filtering capacitors were used. I used recycled capacitors as much as possible as part of my recycling design philosopy. Also I had a few small 6.3V rated capitors from computer mice. Tiny and light, just want I needed. Because I needed a 3V power supply for the motors I went for two battery packs. A 9V battery to supply the main 5V regulated circuit and a 3V (2 x 1.5V AAA) battery pack just for the motors. The 3V supply only had one filtering capacitor on it. But this did mean I had to have two battery connectors on the power board, so two plugs, etc. Small things like this slowly add up to more weight. Finally on the power board went the power switch, some jumper connectors so I could disable either the 3V or 9V power lines (for testing) and various molex connectors (power input, motor connections, power output to main board, relay control input).

With the power/motor board done I was ready for some testing. For the AAA batteries for the 3V supply I was using rechargable batteries (NiMH) so was only getting 2.4V. However Trackbot went well, the speed was good and the climbing ability was excellent. Trackbot would almost go up walls. Shorting the 5V output line to a relay contact would kick a motor into reverse and Trackbot would spin around quite nicely. One issue was the rubber tracks would sometimes come off as they would stick to the carpet a bit too much. Plus I have found over time the rubber has stretched a little.

Next time the main board...

Trackbot part 1

2008-04-19T20:51:00.000-07:00

Trackbot and trailer in action

Trackbot was an evolution on Squarebot but with a microcontroller added to the design (a PIC16F84). The engine controller circuit was based on the sumo bot design from "Junkbots, Bugbots and bots on wheels". However the real inspiration came from a visit to the local Dick Smith store.

One day while browsing in the local Dick Smith store I came across the Tamiya track set and Base plate set in the discount bin. Instantly ideas of a tank like bot came to mind and a purchase was made. However I then had a few months wait while I tried to work out a way to attach motors to the track set. Little did I know that Tamiya also had a range of engine kits designed to go with the track set (both single motor kits driving both tracks and dual motor kits). Once I had one of the dual motor kits (from Jaycar) the chassis was done. Since the track set boggies were bright orange I decided to spray paint them black. Big mistake as the paint just peeled straight off, even after I washed the plastic in detergent. So now they are orange with black highlights. Finally I used the cover from an old floppy disk drive as a plate to sit on top of the chassis for all the PC boards to be mounted on. This also had the advantage of providing some shielding from the motors.

The motors are 3V rated. The engine block has four gear ratios that can be setup. I choose the second slowest as I wanted trackbot time to react to objects and I wanted torque. No point having a tank that can't climb over things. Some of the robot sites suggested replacing the 3V motors with 4.5V motors (the motors are the standard "toy" size engines) but speed wasn't a concern on this design.

The next design issue I had was how to control the 3V motors. My existing motor controllers (SN754410, 4424) didn't support such low power motors. I could make dual H bridges out of transistors but that would make the engine controller quite big and space was an issue. In the end I went with the relay based motor controller described in the "Junkbots etc al" book as used in the sumobot design. A DPDT relay is used with the NC points putting the motor in forward. When the relay is triggered the motors go into reverse due to the cross wiring on the DPDT relay. This means that there is no idle. However not having an idle wasn't really an issue on an obstacle avoiding bot. Also as the normal (no power) position of the relay is for the motors to go forward the power consumption by the motor controller circuit would be zero. I even had some nice small 5V PCB telecom relays to use. The other issue was that I was going to have to have two power supplies. 5V regulated for all the ICs etc and 3V for the motors. I considered just using the 5V supply for the motors (and using some diodes to reduce the voltage) but decided against it.

One ideal I tried to stick to was reducing weight and size across the entire design. I wanted Trackbot to be as light as possible as my next bot would be a sumo bot. Given that there are weight restrictions for sumo bots I wanted to see how hard it was to keep weight down.

Next time more about the power board...

Rodbot

2008-02-20T19:01:00.000-08:00

Rodbot - my first junkbot

My third robot came from the excellent book "Junkbots, Bugbots and Bots on Wheels" by Hrynkiw and Tilden. This book details seven projects utilising the BEAM (Biology, Electronics, Aesthetics, Mechanics) design ideals and recycled material. The projects include solar bots, Bicore bots and Beam bots. The authors explain each project in detail including the where the materials were sourced (eg old tape decks, modems, etc) the circuit diagram and construction techniques. In reality most of the IC chips used you are just going to have to buy but the ethos of recycling materials really struck something in me. The circuit designs are clear but I would have liked a little more explanation into the actual workings of some of the circuits. There was some explanation but at my low skill level I did have to do a few rereads on some of the projects.

Since reading this book I try and make sure all my projects use recycled/reclaimed materials. For example an old computer mouse (the roll ball variety) is a gold mine of parts (phototransistors, wiring, IR leds). Also a junkbot as a certain appeal and has more history attached to it.

Rodbot is based on the third project, a herbie photovore. A truly inspired design using an audio amp chip (LM386) and some photo detectors (I used phototransistors) to make a light following bot. A relay and bump switch is added so the bot can reverse if it hits an obstacle. The engine mounts are made out of hose clamps and chassis from cut offs from a cdrom case (the remains of the case from Squareabout). I loved the circuit. Simple but with a great deal of functionality and the junk construction was just fun to try. I did buy the 386 chip and the battery mount, but all the other components (including the wire) was recycled. The wheels came from an old battery car racer and give Rodbot great grip. I also reverse biased the phototransistors (ie put them in backwards to normal) to give a much greater response to light. With the phototransistors setup normal Rodbot turns within a 20cm arch. Reverse biased and he turns on the spot. I left the eye stalks attached with U-tack so that there were easier to direct. Also Rodbot pretty much flies along so crashes (and mild damage) are normal.

I plan to also make one of the Bicore designs from this book at a later stage. But even if you aren't going to make any of these projects the book itself is worth a read. Great ideas, well written and something I have reread a number of times.

smells like roundabout, looks like squareabout

2008-02-11T22:32:00.000-08:00

My second robot was again based on a design by David Cook. This time from the "Intermediate Robot Building" book. This robot was called Roundabout (as it was rounded in design to help it brush past objects) and is an object avoidance design. It uses two IR detectors to determine if an object is in it's path and uses a motor control setup to steer out of the way. The design in the book is in two parts. The first only using logic chips, the second part adds a daughter board with a microcontroller to improve the avoidance abilities.

Again the book goes into a quite detailed analysis of the various components used including IR detectors, motors, motor driver chips, chassis manufacture, etc. Rather than just present one solution for most sections of the robot (power supply, motor control, sensors, control) various alternatives are presented and critiqued. This is superb as it allows you to not only build the robot but also understand the design decisions made. This is normally lack in most other robot building books I have read.

In the end I used a 7805 voltage regulator as the core of the power supply, an SN754410 motor controller chip and the presented IR signal generation and detection circuit. I had plans to do the daughter board but that ended up as a separate robot (Trackbot, details later). The motors were recycled off Sandwich who to this day still is without wheels. Power is 6x1.5V AAA batteries. Originally I used the same type of plastic lunch container as a body by then made a new body out of a casing of a CDROM drive. Hence Roundabout became Squareabout.

Squarebot in all it's glory

For the CDROM body I first gutting everything, just keeping the case itself. The case is quite good in design as there are four screws keeping the top of the case onto the body. Also the sheet metal is quite easy to machine (but less forgiving to mistakes than plastic). Disadvantages is the weight. Not an issue for the motors (as 9V they generate approx 1.5kg torque and the whole robot weights 650gm) but it does reduce the battery life. This was also a test of me being able to machine with some precision a body. However the chassis design isn't great for the task as the exposed wheels and square body means Squareabout gets caught on things. Also as the new case meant the various parts of the robot were closer together the cables are too long. I didn't bother to redo them as the chassis rebuild happened some time after the original robot was done.

The result? Squareabout goes ok, but the range on the IR emitters is quite under what is described in the book. Most of this is due to the fact I couldn't get the correct parts and the alternate parts worked, but not as well. But Squarebout still avoids objects, trundles along at a slow but steady pace and has so much torque it can climb up walls. The motor chip is quite good as it is dual voltage. 5V for the logic part of the chip and any voltage over 3.5-4V for the motors. So I ran a direct line from the 9V power supply to run the motors. All the logic chips are powered by a regulated 5V off the 7805. I found the cutting of motors from one direction to another generate a large amount of interference with the IR circuit. Originally the design used a single 9V battery but the motors drained that out two quick so I swapped to the 1.5V batteries (and started using rechargeable batteries to save money).

Since I never had time to sit down and do Squareabout in one hit I made it out of modules. Two ideas were behind this. One being that I could recycle the modules into other robots. The second being that I could compete a module in one day, this getting things done. There are three modules in the end. Power, motor control and finally detection circuit and logic brain. I used Molex connectors for all interconnections between modules. All wiring was point to point, ie by hand not using a PCB. It used predrilled blank prototype circuit boards.

The power module as stated previously is based around a 7805 voltage regulator with various capacitors to filter the output. There is a diode to provide reverse battery protection and a power switch. There are both unfiltered battery voltage outputs and 5V filtered connectors.

The power module with the 7805 in the center, connectors on the sides.

The motor control module is based around the SN754410 chip. Good dual H bridge chip capable of driving two motors in forward and reverse. Various power supply capacitors were added to the chip.

The motor chip.

The sensor/detection circuit/logic brain is straight out the book. Nothing that fancy.

Detector circuit with IR emitters and detectors out in front.

Finally a shot showing the motors and battery pack underneath the top board. This had the advantage of providing some shielding the IR circuit from the EMF off the motors which did cause some issues esp. when the motors are cutting from forward to reverse (or vice versa).

Battery pack bolted to the top plate, Sandwich motors below. Garage in the background :)

when sandwich containers attack

2008-02-02T00:38:00.000-08:00

My first robot was from the excellent robot book by David Cook, "Robot building for beginners". It is a line following robot based on the LM393 chip, housed inside a plastic sandwich container called "Sandwich". Unlike many 'make your own robot' books this book covered just one robot in detail. The author goes into great detail not just on the electronics but also the construction techniques. The electronics level starts from a very basic level but always assumes you have a brain and you are happy to us it. Each chapter builds up the various sections necessary to make the robot. The author also covers other details such as DC motor operation, making wheel couplings, soldering, body construction, etc. In all an excellent intro to robot centric electronics, robot construction techniques and all the fundamental base skills needed for future robot building.

The main problem I had with Sandwich was getting the parts. All parts needed are detailed put being in Australia I had to find the Australian equivalent. For some parts this was easy (transistors, leds). Others were harder due to the lack of range in Australia (gear head motors, LDRs). Ordering from the USA wasn't an option due to the huge postage costs. The worst was a flat rate of $30US, regardless of the parts ordered. Of the Australian stores Jaycar was by far the best (in terms of range and staff help).

Due to the simple nature of the circuit there is no need to make a printed circuit board. Point to point wiring is fine, although but the end of the design my wiring was getting a bit messy.

When wiring gets messy. Also showing off the LDRs that track the line.

I used a plastic sandwich container as it was cheap (less than $1), easy to work with (read chop apart) and light but strong esp. with the lid on. I couldn't find any wheels so originally I used some old Mecanno pulleys with rubber band wheels. These were later replaced with some Tamiya wheels. The photo is of the first set of wheels.

Sandwich in all his plastic lunchbox Mecanno wheel glory, with a close up of the motherboard.

lamer bloggers destroy web experiences

2008-01-29T02:38:00.000-08:00

Hmm, been awhile. Wife and I are having a baby real soon. With the month off perhaps the digit will be removed and some pictures will actually appear. Also the purchase of my new eeepc may help as the cool toy factor is still high at the moment so any excuse to use it (ie blogging). I'm still really a HTTP 1.0 kind of guy so unstructured posts without some kind of hierarchy is difficult to embrace.

Welcome all

2007-06-24T01:26:00.000-07:00

Hello all,

In an effort to help others down the road of robot construction I decided to put together a bit of a journey through the robot projects I have done to date. The emphasis is more on what I found out along the way rather than the end product. Hopefully this will be useful to others. My interests in robots comes from wanting to do something with electronics but not involving the field of audio and car projects. Constructing small robots fits the bill. I especially like the construction aspects and enjoy converting electronic junk into robot parts. My end goal is probably in the area of the sumobots as that is a nice convergence of technologies and construction techniques.

Hello world

2007-06-24T00:15:00.000-07:00