# Physics(electricity) project help

1. May 4, 2004

### recon9

Hello, I am in grade 12 physics and we have to make a project using electricity then explain it to a bunch of grade 5ers. Me and my friend are making a small car with tether and then a controller. We want it to be able to go forwards/backwards and turn, plus have some other gizmos on it. Our first problem is that we cant seem to hook up the circuit correctly to get the forward/reverse. How we have it set up is with 4 switches, 2 for each motor. One switch to make a motor go forwards and the other to make it go backwards. Then use forwards on one motor and reverse on the other to turn. Could some one please explain how to hook up this circuit? Thanks.

2. May 4, 2004

### Cliff_J

Ok, you hopefully have the correct switches (for your case a DPST or DPDT would work) so assuming you have those switches its easy to hook up. I'll give the example with DPDT that has a on-off-on action as its foolproof for the driver of the car. This could also be done a pair of DPST switches but if both were on at the same time they would short out the battery.

You have your battery + & - and wire each one to a 'pole' (pivot) part of the switch. Now you wire up the motor leads to one side of the contacts and the other contacts but flip around the polarity. When you move the switch one way the motor spins one way, and moving the switch the other way reverses the polarity so the motor spins the other way. Here's the second link I found in google, plenty more are out there but this one is pretty clear:
http://www.eleinmec.com/article.asp?12

Other switches could be made to work as well, but they might require more forethought into making the appropriate connections. Drawing this out on a sheet of paper helps a lot. Many possibilities exist for how to get this done and depends on the parts you have access to. Good luck. :)

Cliff