Okay, so check out page 6 of the datasheet I included. You can see that if you put in a button or switch in the controller that shorts pin 6 to ground you will activate the third "Turbo" channel. This causes the receiving chip to output 3v on its pin number 12.



Now, we can't just power a DC motor directly from that RX chip. First of all, the voltage probably isn't high enough. Second of all, the amount of current needed to power the motor is absolutely not going to be provided by that little chip (I measured 1 Amp for the Nerf gun!). We need something else to take that 3v signal from the chip and use it to turn the DC motor in whatever toy you're hacking on and off and power it directly from the battery. That something is the TIP120 transistor.



The two tutorials I listed in the introduction of this Instructable pretty much spell it all out. I made up a drawing of the circuit, but basically it is just a circuit that takes the 3v signal from the RX-2 chip and switches the battery power on and off for the motor. The diode, pointing AWAY from ground toward the transistor, is to help prevent back voltage from the motor frying the RX-2 chip.