RC stands for remote control, but where in the situation I have no radio transmitter, it was only reasonable that I had better used IR LEDs and phototransistors for the receivers. I'm only 12, have a restricted budget of no more than $30, and less time on hand. In fact, school resumes on the 17th of January, 2009, and I won't be working on all this stuff. So if anyone replies, please study this question carefully. So now I have a remote control, IR, of course. I know how to complete a circuit with a switch, using an IR phototransistor, a 330 Ω resistor, and of course the cell. So now say I have made a small car using cardboard wheels and a cardboard base. In fact, I'd probably use wood for the same. Here is the question: I need two motors to activate different sets of wheels. I have taken two IR LEDs for their respective two phototransistors on the receiver end. How do I make sure that one IR LED only activates its respective transistor? Should I buy the diodes in sets, from different shops? And if this bungling should happen, and I prefer to use one IR and another UV LED, I have my second problem here. The problem is that I find only UV photodiodes and not phototransistors. Please help me with this, either by posting a schematic diagram explaining how I make a switch with a UV photodiode and the place where you get them with the UV LEDs as pairs, or by routing me to a site where you find pairs of UV phototransistors and LEDs.