I assembled the kit (using my new Ersa i-Con nano soldering station) without problem, but am experiencing really strange behavior in the wobble mode.
In straight-ahead mode, it works fine: it steps ahead in a straight line. Both motors pulse at the same rate, and the sensitivity pots do a fine job of calibrating the LDRs’ sensitivity, so it walks toward light as expected. (Edit: See notes in next post.)
In the wobble mode, it goes in circles. The left motor (controlled by LDR2, T5/6/8) turns essentially constantly, at a pulse rate obviously higher than that of the other side. Only if LDR2 goes completely dark does the left motor stop turning, allowing the bug to re-target the light, but as soon as it gets any light on LDR2, it goes in circles again. LED2 shows that it’s running at a far higher rate than LED1.
I began by measuring the values of all the components with a multimeter, and everything checks out. Without knowing the nominal values for various test points, it’s hard to say whether I’ve tested thoroughly.
Now here’s where it gets interesting: While testing with the scope, I also noticed that the motors produce massive amounts of noise into the circuits (spikes many times higher than the +3V rail, about 60Vpp!). If I use my hand to stop the motors from turning, everything goes back to more or less clean square waves, and the power going to the two motors is the same (180˚ out of phase, of course).
With the motors held down to stop them turning, everything in the circuit tests as I would expect it to, and it behaves correctly. But let the motors run, and it goes berserk!
If I use a jumper to put both motors in parallel (so they always run at the same time), the bug goes in a straight line in either mode. (Pulsed in straight-ahead mode, continuously in wobble mode.)
What can I do to fix it?
Thanks!
), and now it’s even weirder… it’s basically turning away from light.
