Need help with reversing DC motor circuit - Electronic Circuits Projects Diagrams Free

perni_a · 4th November 2009, 01:04 PM

Hi all,
Im needing help with a small personal project of mine, and I'm only starting out with working with components.

I have a 12V DC motor and I need it to do the folowing...

When 12v+ is applied, I need the motor to operate from the home position in the forward direction (clockwise).
When it reaches a point, triggered by a N.O. momentary switch, I need the motor to stop.
When 12V is removed, I need the motor to reverse direction (anti-clockwise) back to the original starting position and stop (again stated with another N.O. momentary switch) - and ready to go again when power is applied.
Contstant 12V is available for use, plus also switched 12V to start the process and end the process.

Any help you guys can shed would be greatly appreciated.

Pommie · 4th November 2009, 01:34 PM

Have a read of this thread and see if it answers any of your questions.

Mike.

MikeMl · 4th November 2009, 01:35 PM

I posted this somewhere about a week ago:

Gary B · 4th November 2009, 03:23 PM

This could be easily done with a single 12 volt DPDT relay if you were to use NC limit switches instead of the NO specified. I don't have a graphics program to draw a picture so here it is in words:
+12 control to relay core and through one make contact. That movable contact to one side of the motor and the other side of the motor to to the other swinger. the second make contact goes to the limit switch and then to ground. the second break contact goes to fixed +12. The break side of the first break contact goes to the other limit switch and then to ground.

In other words, lets call the relay K, its contacts as K1MFB & K2MFB and the two terminals of the motor as M= and M-. +12 control to K and K1M. the other side of K coil to ground. K1F to M+. K1B to limit switch and the other side of the switch to ground. M- to K2F. K2B +12 perminant power. K2M to other limit switch and the other side of that switch also to ground.

To use the specified normally open switches, you have to use an additional relays or transistors to make it work.

perni_a · 5th November 2009, 12:49 AM

thanks Gary B, that was exactly what I was after!

MOSFET KILLER · 5th November 2009, 02:10 AM

H-Bridges or Full Bridges are sometimes used to drive electric motors, they can use any transistor that can handle the current of the motor. If you use transistors you will need a lower voltage to turn them on, but transistors are trickier to use than relays.

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4th November 2009, 01:04 PM	#1
perni_a	Need help with reversing DC motor circuit Hi all, Im needing help with a small personal project of mine, and I'm only starting out with working with components. I have a 12V DC motor and I need it to do the folowing... When 12v+ is applied, I need the motor to operate from the home position in the forward direction (clockwise). When it reaches a point, triggered by a N.O. momentary switch, I need the motor to stop. When 12V is removed, I need the motor to reverse direction (anti-clockwise) back to the original starting position and stop (again stated with another N.O. momentary switch) - and ready to go again when power is applied. Contstant 12V is available for use, plus also switched 12V to start the process and end the process. Any help you guys can shed would be greatly appreciated.

4th November 2009, 01:34 PM	#2
Pommie	Have a read of this thread and see if it answers any of your questions. Mike.

4th November 2009, 01:35 PM	#3
MikeMl	I posted this somewhere about a week ago: Attached Thumbnails __________________ Mike ML.

4th November 2009, 03:23 PM	#4
Gary B	This could be easily done with a single 12 volt DPDT relay if you were to use NC limit switches instead of the NO specified. I don't have a graphics program to draw a picture so here it is in words: +12 control to relay core and through one make contact. That movable contact to one side of the motor and the other side of the motor to to the other swinger. the second make contact goes to the limit switch and then to ground. the second break contact goes to fixed +12. The break side of the first break contact goes to the other limit switch and then to ground. In other words, lets call the relay K, its contacts as K1MFB & K2MFB and the two terminals of the motor as M= and M-. +12 control to K and K1M. the other side of K coil to ground. K1F to M+. K1B to limit switch and the other side of the switch to ground. M- to K2F. K2B +12 perminant power. K2M to other limit switch and the other side of that switch also to ground. To use the specified normally open switches, you have to use an additional relays or transistors to make it work. Last edited by Gary B; 4th November 2009 at 03:36 PM.

5th November 2009, 12:49 AM	#5
perni_a	thanks Gary B, that was exactly what I was after!

5th November 2009, 02:10 AM	#6
MOSFET KILLER	H-Bridges or Full Bridges are sometimes used to drive electric motors, they can use any transistor that can handle the current of the motor. If you use transistors you will need a lower voltage to turn them on, but transistors are trickier to use than relays. __________________ Metal-Oxide-Semiconductor Flame Effect Transistor