I've been on a mission for years to shrink down the Solarbotics photovore circuit as small as I can.
Finding a SMT 1381 voltage trigger equivalent has been the hardest part, but this week I finally found the magical TC54!
I tested it in a solar engine, it worked perfect and finally finished my robot!
At only 10mm x 10mm in size, I'm pretty sure this is one of the smallest photovore BEAM robots!
Step 1: Part List
x4 1000uf TANT SMT capacitors (T495X108K006AT)
x2 photodiodes (BPW34)
x2 Hubsan quadcopter motors or Hexbug nano motors
x2 100nf SMT 0603 capacitor
x2 2N3904 / 2N2222 (BSR14) transistor SOT-23
x2 1N4148 SMT diode
x2 2.7v Voltage Detector TC54VC2702ECB713
x1 Solar cell (3v MP3-25 Powerfilm solar cell)
Step 2: The Circuit
I followed the original Solarbotics photovore circuit.
I downloaded the data sheets for all the components, and then really it was a case of laying them all out loosely on a board and working out what pins needed to go where.
I'd advise you sketch them out and follow my PCB layout as this was I think the best position for the components.
It can be very difficult to solder, I used a x10 magnification aid with strong LED light source.
There are x4 SMT TANT capacitors on the reverse of my PCB in parallel and connected to the positive and negative of my solar cell.
The motors are vibrating motors and soldered on the side of the caps.
Any questions or help, please don't hesitate to ask me!
I have been soldering for over 15 years!