Chobot is a simple vibrobot with a photo-popper circuit.

To get the required voltage of ~3V, it uses 6 solar cells in series. That’s quite wasteful, but if you have enough cells, why not.

Chobot moves using vibrations generated by spinning an asymmetric weight attached to a motor. It’s not very efficient, but it works - somewhat.

The legs are from some “Kinder Surprise” toy. Motor is from a CD-ROM drive (as usual - I have a good collection of those).



Chobot uses a photo-popper circuit with a CMOS version of NE555.
(source: solarbotics and hawelson)


The circuit works OK, but needs quite high voltage - that’s why I had to use 6 solar cells.

You can look for other similar circuits on this solarbotics page.

How it works

The current from solar cells is rarely enough to power the motor.

A photo-popper slowly charges a capacitor, and then connects it to the load and discharges it with higher current.


  1. Solar cell charges a capacitor
  2. When cap voltage reaches upper treshold (~2.5V), motor is connected
  3. When the cap is discharged and voltage drops below a lower treshold (~1.9V), motor is disconnected.