Using a DPDT to automatically reverse the polarity of motor

I am currently working on a project that requires a motor to run this way and then hit a switch that would enable it to reverse its polarity. However, I have to wait for a signal from an LDR and this signal is what would drive the motor the other way.

Is there an automatic DPDT switch that I could use?

Thanks!

"All in one" I seriously doubt, easy to build with minimal components - yes.

Voltage & current requirements of the motor?

Start reading here... or Google "H-bridge switch" or "h-bridge relay"
http://www.mcmanis.com/chuck/robotics/tutorial/h-bridge/index.html
or
http://www.dprg.org/tutorials/1998-04a/

This is a circuit I whipped up awhile back for a fellow who used it in a model of a German WWII Tiger Tank:



It could probably be modified to suit your needs, but you'll need to give more specifics about your LDR and it's resistance when illuminated and dark.

The diagram shows two relays. The actual relay used was a dual form C H-bridge relay, NEC EP2 series. These are available from Mouser.com
You don't have to use an H-bridge relay though; a pair of SPDT relays could be used.

I add a pic of how you can use a DPDT switch to reverse the motor direction. I use it all the time with no problems

janej,

We need to know more about the motor, is it AC or DC, if AC... is it single phase or three phase. For a good circuit, accurate motor information is paramount.

williamj