RC Car Assembly Details

The following instructions describe how to wire an rc car controller to the parallel port of a pc.

We typically start with an off-the-shelf RC car in the $30 - $40 range. Try to find one that has forward, reverse, left, and right controls. Usually, this will come with a two-joystick controller.

It is easiest to wire up a 4-channel (forward,reverse,left,right), digital system.

Click here to download a NeatTools "ntl" file to use with this controller. Right click on bluecar.ntl to download the file.




The photo on the left shows an opto-isolator circuit that is used to protect both the rc controller and the computer.

The photo on the right shows a close-up of the controller's internal circuit board.

Parallel Port

Wiring Create a small circuit board using 4 opto-isolator (NEC #2501) chips and 4 resistors (330 ohm) according to the drawing above. Pin 25 on the parallel port is the ground. Wire this to each of the resistors on the opto-isolator board. The other end of each resistor is wired to the opto-isolator chip. Wire Pin 3 on the parallel port (signal wire) to the leg of the chip closest to the dot printed on the surface of the chip. Wire Pins 4,5, & 6 to the consecutive chips. There are "contact points" on the controller circuit that make the car move when the thumb switch is rocked in either direction.(see photo) This can be tested by connecting a ground wire (from any ground point in the circuit) to the part of the copper film to complete the circuit and see if the car moves. Once you've established the contact points for a direction, solder a ground from the opto-isolator to the ground on the circuit. Finally, solder the signal wire from the opto-isolator to the contact point. (Note: you might have to scrape off some of the coating on the copper to solder on the contact wire.) Also, make sure that the voltage for each pin coming out of the parallel port is 0-5 volts. (0 is off, 5 is on). Try to get the greatest voltage differences for optimum opto-isolator functionality.

This page created by Rahul Panesar and Matt Carbone. Last updated 5-15-99