Remote control of DC motor

Thread Starter

xxxyyyba

Joined Aug 7, 2012
289
This is PWM controller I bought for speed control of DC motor http://www.ebay.com/itm/6-30V-DC-Motor-speed-Controller-Reversible-PWM-Control-Forward-Reverse-Switch-/162002954574?hash=item25b820e94e:g:RAMAAOSw6EhUQgOp
DC motor rotation direction is controlled using switch: when switch is in position I motor rotates in one direction and when it is in position II motor rotates in opposite direction.
Since I need to have limiters also, I removed this switch and shorted controller on this way:



Instead of only motor, I put on output of controller DPDT switch, limiters and motor. It looks like this:



Here is schematic:


Now I can change direction of rotation using DPDT, I have also limiters and of course I can control speed.
My question is, is it possible to remotely control direction of rotation instead of manual control using DPDT?
 
Last edited:

MaxHeadRoom

Joined Jul 18, 2013
21,182
Yes, use a relay with the same contact configuration, also you can do it with only two wires out to the motor and put each limit in series with the motor, place a reverse biased rectifier across the limit terminals to allow reverse.
Max.
 

Thread Starter

xxxyyyba

Joined Aug 7, 2012
289
Here is schematic for control of rotating direction of DC motor using two relays:



How can I add two limit switches here?
 

crutschow

Joined Mar 14, 2008
25,242
Depends upon what you want the switches to do.
Do you want it to automatically reverse when a limit is reached or do you just want to stop the motor?
 

Thread Starter

xxxyyyba

Joined Aug 7, 2012
289
Here is diagram with Voltage source which is used with relays. Is it good idea to use one source for two coils, like in diagram? Using switch S1 relay RLY1 will be turned on/off and using S2 RLY1 will be turned on/off.

 

AnalogKid

Joined Aug 1, 2013
8,532
Your drawing shows switching the positive battery to one relay and the negative battery to the other. Nothing wrong with this, but for consistency you might consider having one end of each relay coil connected directly to the battery negative terminal, and switching the positive terminal to each coil through a switch. Also, you should add a diode across each relay coil.

ak
 

Thread Starter

xxxyyyba

Joined Aug 7, 2012
289
Thanks for answer. You mean this:


?

Input voltage (PWM input) is DC and if it matches relay coil voltage, can I use it instead of battery V in previous diagram, like this:


?
 

MaxHeadRoom

Joined Jul 18, 2013
21,182
You could also do it simply by reversing the two switch wires instead of jumpers using the same relays, the out put to the motor could still be a pair with a limit switches in series with the motor with the diode across them.
You may be able to use the low logic voltage on the board for the relays, most likely the pot has the low voltage across it.
Max.
 

Thread Starter

xxxyyyba

Joined Aug 7, 2012
289
Max, if I understood, you say that by applying same principle as in schematic below, I can reduce number of wires which go to motor (there are 5 wires (green) in my case)?

 

MaxHeadRoom

Joined Jul 18, 2013
21,182
Yes, a pair as you have it.
The motor will automatically be off when on a limit so maybe no need to have anything other than a main switch for a permanent off condition.
The reversing relay's would be on the 4 terminal reverse in/out.
Max.
 
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