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Off the "shelf" 12V 15A PWM module

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Aug 31, 2009
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pwm module

Hi Everyone

First post. I put this in Elementary but I think that for my question the forum might like to create a lower category still !!

I found your forum on Google and saw that questions had been asked about PWM. I searched on the forum but still need to ask a question or two.

I need a speed controller for a pump which is 12V Max 8A. I found out about PWM and I found an off the shelf module (made in China). I have not got involved with any custom DIY "electronics" before.

The off the shelf module is here **broken link removed**

First question is please will this do the job and match the simple technical requirements?

The wires offered by this module confuse me and I need some help please.

My pump has a black lead and a red lead.

But the diagram on top of the PWM module shows Power In with RED=VCC and GREEN=GND.

For the Motor it shows WHITE and YELLOW.

Can someone please tell me what to do given the pump only has RED and BLACK?



12v pwm speed control

Almost certainly your the red wire is the positive supply and the black one is negative. If you have the pump running at the moment, use a test meter (very inexpensive at DIY stores if you don't have one) to check that is the case.

Looking at the photographs, the white and yellow output wires could be either way around. The only way to tell is again to use the test meter. Connecting a DC motor backwards for a short length of time doesn't usually damage it, but it will run in reverse which is usually obvious. (sucks instead of blows!)

Other than the un-labelled wiring, from the specification shown, it looks like it should do the job.


12v pwm controllers for a water pump

Hi Brian

Thanks for the input. Red on the pump is positive and Black is negative.

The Power In on the module are as you can see red and green. Both red and green also go to the potentiometer. The yellow (one of the two labelled motor) also goes to the potentiometer. Can anything about the yellow, in terms of polarity, be deduced from that?

If I were to connect the Power In the wrong way round to the PWM module could that have and deleterious effects to the PWM module?

What if both the Power In and the Motor connections were both the wrong way round?

I don't want to run the pump the wrong way round because the manufacturer warns about dry running on the warranty (and the water flow to the pump is uni directional, if that is the right description).

It sounds like I need a lesson on how to use a test meter then before I connect this up.



diy 12v pwm

Connecting the supply to the PWM module backwards would almost certainly damage something so please don't try that! The pump should be OK for several seconds without harm if you do have the wires reversed so I wouldn't concern yourself over that. It sounds like it has water cooled bearings so a short burst of power wont overheat it.

Looking at the photograph on the web site, there are three thin wires which would be the ones to the potentiometer.

The thick red wire is the incoming 12V positive, the thick green is incoming negative.

The thick white is *probably* the positive to the pump with yellow being negative but if the instruction booklet doesn't tell you, the only way without a meter is to try it out. You can always set it to minimum voltage then gradually increase it if you are concerned about the motor polarity. Use a car light bulb instead of the motor to check which is the low voltage end of the control.


I followed your link; had a look at your control. This looks pretty straight forward to me. I suggest that you hire a tech. because this is purely too simple for you.

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