Bartholomew is the original robot that lights up when you touch his heart. He is a demonstration circuit of a Darlington Pair transistor circuit.
Because the circuit is not turned on unless you touch the heart the batteries can last for many years. Some people have reported the robot still works after 5 years.
He consists of 2 each of the following; RGB flashy LED's, 2N2222 transistors, CR2032 batteries. The heart and circuit on the back are made from copper tape. The body is made of thrifty white panel board from Home Depot.
I designed the robot in Inkscape a free vector editor. I use a laser cutter at HeatSync Labs Hackerspace to cut the body of the robot. A vinyl cutter to cut the heart and other copper circuits. Typically I prep the robots in advance and have this as a soldering workshop.
If at some point the batteries do go low you can easily replace them with new CR2032 batteries. Just gently push the old batteries out from the back to the front. Push new ones in similarly. Going the other way may cause the tape to push away from where it should be. The copper is a thin foil and can easily tear. If you should have problems during a battery replacement it should be possible to add new tape and solder things together.
I'll be adding some things to this page (photos, schematic, and design files), but please use the contact form if you have questions in the meantime.