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Lotus I

I'd like to introduce you to "Lotus I", my first walker.

Front quarter view of Lotus  
Click here for more photos!
Click here to go to the video page!

Lotus I is based on Ian's "Almost complete walker" circuit found at Although I made a few changes:

  1. I used a 20 uf capacitor instead of 30 uf. This is for reverser; bigger cap, longer reverse time. (20 even seems to be too long for me.)
  2. I couldn't get 1.6M resistors, so used 1.5M
  3. Guys at many different shops told me there was no such thing as a 2.5M resistor. I had a choice of 2.0 or 2.7; used 2.7M.
  4. I used an IC socket. (I recommend this for newbies. When you get + and - mixed up, you can replaced the IC you just fried.)

I can say once and for all that, yes this circuIt does work, and not too shabby either in my opinion! The reverser works great too! Lotus backs up for about 11 seconds on a 20uf cap. I had a hard time soldering my "feelers" to the springs. I resorted to epoxy..

Keep in mind this is my first bot; haven't built a solar roller or photopooper yet. Heck I hadn't even touched a soldering iron until I started this project!

Thanks to IAN! What a help your page has been! (watch the H-Bridge, be sure to read the note on step 3. I think I'm the one that discovered this) Also thanks to you folks on this mail list for your input too!


Aluminum angle bar (very light) 7" long. Notched for angle at front and held together with small machine screws. I used rubber O-rings for washers where the IC PCB is attached to the frame.

The frame has LED's showing when legs fire (very nice touch I thank whoever recommended this).

Two CS-61 Hobbico Standard Servos $10 each (boy I think they're ugly, I much prefer the look of bg micros motors I've seen in pics).

1/8" welding rod. I needed to practice on the leg symmetry a lot, so I used coat hangers to get the shape just right. Leg ends are coated with plasti-dip. I used longer (1-1/4") machine screws for "stops".

4.8 V rechargable battery. The manager at Radio Shack gave me all he had (5) for $10. He wanted 'em off the shelf. I attached it to the frame using small flexible springs from the local hardware store. (see bottom view)

  • Speed of 1 foot per 2 seconds! (on a fresh charge)
  • Tactile Sensors/ Reverses for 10 secs
  • Flashing LEDs
  • Chirps When In Reverse (really cool!)
  • Never ever tips over!

Send me your comments -- I'm interested in what you think. Sparky

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© 2000 by Sparky. Last updated 2000-02-28.