Symbol Engine

I have been working with Tolga on a 4 motor walker. After taking care of the electronics we started working on walking dynamics. Figuring out the timings needed to control this beast wasn’t that easy. Luckily Tolga had a working Wowwee Roboquad lying around. So we had a chance to analyze its walking patterns.

Here is the basic schema of a 4 motor walker. You can see the numbering scheme we used to identify each motor. Arrow points to which way the robot is going when we say it is going forward. Motors are running counter-clockwise with negative voltage and clockwise with positive voltage. Now to get to the juicy part:

• Please note that the patterns for rotating are 2 times longer than the patterns for movement. As a result turning is slower.
• If your robot is moving in very small steps, try longer delays between steps.
• If the robot is moving faster in one directionor leaning slightly to one direction while walking, there is probably a problem with its weight distribution. Try to distribute the weight as equally as you can, especially between back and front

Popularity: 10% [?]

I finally had the time to try out Spaceman Spiff's Color Fix on my DTV. So I took my DTV apart , heated my soldering iron and tried to focus my eyes on the teeny weeny resistors. First let me tell you this: Piggybacking Surface mounted resistors is NO PICNIC.

You need completely steady hands, eagle eyes or a stereo microscope, a really good tweezer to grip the tiny resistors, a soldering iron with heat control and a good quality soldering& paste flux. I had& none of them. After 2 hours of agony I could only solder one (1) resistor into place. Then when I accidentally touched the one I soldered when I was trying my luck on the second one, the first one came off… Complete with the original resistor on the DTV board. Talk about pain.

I left everything on the table and fired up my a1200 to normalize the levels of stress hormones in my blood.

The other day I decided it would be much easier to take the original resistors out and solder new ones in than to try to piggyback them. And here it is, the turning point:

Spiff's page says these resistors should ideally be 165 ohms. What I had in hand was the 220 ohms resistors I prepared for the easy fix. The ones on the board where 680 ohms, so I decided to try my luck. 220 ohms is much closer to the ideal value than 680. I soldered them in and as I thought it was much easier.

The result is as anyone can guess, not as good as the original fix, but is much better than the original buggy board. It would have been much better if I had resistor with a closer value to 165 ohm. So I dub this fix Half a Spaceman Spiff's Ghetto Color Fix, or HaSSGCF.

So the moral of the story boys and girls is, it's much easier to replace SMD's than to solder them piggybacked if you don't have right tools.

Popularity: 43% [?]

I got meself a PAL DTV recently. These things are pretty cool out of the box. But if you want to get more out of your DTV, there are many hacks around the net. Here is a checklist of the hacks I want to make for mine. It may prove useful to some people.

I'll add my experiences doing these hack here somewhere when I find the time to do them.  

1- Fix the colors:

    PAL version of the DTV is cursed with a buggy video generator. White is not white at all, and some colors are very hard to distinguish. If you don't like your DTV with ghetto colors, try spacman spiff's easy colorfix: (scroll down to easy and better fix)

Spaceman Spiff's DTV colorfix

Note: I have tried this hack with limited success. You can read about it here.

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Popularity: 48% [?]

I was looking for a1200 schematics and all I could find was IFF files in a zip on Aminet. I had to struggle to convert them so you dont have to. Here it is:

Commodore Amiga 1200 Schematics in PDF format @ Symbolengine

Amiga 600 Schematics also available.

Note: WOW! 1000 downloads in a month. I'm impressed :)

Popularity: 85% [?]