Older blog entries for c6jones720 (starting at number 24)

I've developed a super simple servomotor/speed controller interface using only three transisors and a comparator. It can be used to convert almost any DC motor into a servomotor using standard PWM radio control signals. Im planning on using the design to control the legs of my droid. I did develop another servo design earlier, but it was full of op-amps and too fiddly to set up. This one just works...

I finally decided to bite the bullet and actaully start doing something with the bits of android on my shelf. I've built a servo waist joint and lead acid battery compartment which both seem to work quite well.

I started playing with hip motors for the two legs (810:1 ratio mind!). I dont know if the thing will balance properly when I've finished it but I'm going to build it just the same. I've ordered a pair of Hitec 815BB servos for the shoulder joints which should allow the arms to lift more than 200g. The old Hitec 715s were good but I ended up burning one of them out with a dodgy PSU.

I swear I'm going to lose the deposit on my flat because of all the metal swarf and solder in my carpet, but Oh well, I cant help being a compulsive robot builder!

Over the weekend I finally sat down and decided just what I intend to do with my droid. I've decided to put the new mobile robot design off until a later stage and continue developing for my droid instead. I finally gutted the insides and all the wiring (British systems always contain tons of funny wiring). I've decided to replace all of the electronics with PIC based systems where appropriate.

I plan to add a robby the robot type graphic equaliser but using electroluminescant adhesive pads or something similar. I've seen them but one thing I was wonding though was where do you get them from?

Over Christmas I finally discovered PIC. Its amazing how simple it all is all of those circuits I used to make to drive servos and do signal processing for sensors are all completely obsolete now. Its PIC all the way for me! Now Im in two minds as to whether to continue working on my droid (which I gutted but never rewired after I met that girl) or to start work on a new EOD style mobile robot using my new chips?

I watched the DVD of Short Circuit the other day. I hadnt seen the film for year and forgot how enchanting the storyline was. After watching it I was left thinking about my droid. I've left it alone for so long that it is probably feeling quite neglected! In the new year I intend to carry on working on it and actually finish off giving it a pair of working legs.

I was at home putting the finishing touches on my new powerfull servomotor design. My mate Rich called me and said to come on out down the pub. Okay! I said thinking I'd complete building the rest of the robot leg later, I ended up bumping into a girl that I hadnt seen in 15 years! Its crazy, she was impressed by my droid when I showed it to her! I think I'm going to have to put my experiments on hold for a while. Experience shows that girls need a little more attention than robots and computers.

Sail arm servos are not quite powerfull enough for the legs of my droid so I'm going to use high torque dc motors intead. I've figured out an easy way to make powerfull servo motors and electronic speed controllers which use the same control signals as standard model servos. I'm sure that will do the trick.

To dafyddwalters, its a real shame that the landlord didnt like your robot. Last time I bought a robot into a pub I ended up with more attention than I wanted too.

I've been working on a life sized droid for about 4 months now its got working arms, head, torso, spinal column and all that sort of stuff. One thing though if your doing this sort of project in England, getting parts sent to your home address is an absolute nightmare. Maplins need to do a proper delivery service...

I found out about running my PC off batteries. The last time I tried something like that a 486 PC drew about 13A from a 12v source. With a UPS and PSU the Pentium PC I tested only drew 4A! I think that that is acceptably low to be used on a large mobile robot. The only thing I have to do now is make the whole power system lighter...

Heres a thought, Our workplace flooded and they ended up scrapping a load of wet UPS's, so theres a load going spare. For ages I've been meaning to use a PC as an embedded system on a large mobile robot. The thing thats always stopped me doing this is making a lightweight power supply with a negative voltage. Im toying with the idea of using a UPS as a mobile power source for a normal PC.

I know that in theory is electrically inefficient to use a UPS and a PC power supply together like this for mobile power, but I.m toying with the idea. Has anyone done anything quite like this? If so did it work?

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