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How can I control the speed of this motor? Help a confused dude out? Answered

Hi guys. I want to run this pump to pump water. I also need to control the speed it pumps water at, ideally using a little twisty knob thing. Here's a link to the pump/motor - http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItemVersion&item=271484020192&view=all&tid=1446260598017

I'm a noob at this kind of stuff, but the phrase pulse width modulator or something similar has been mentioned. Is there a cheapo off the shelf thing I can buy, or am i looking at a little bit of building/soldering?

And! But! Also! I'm UK based, so I don't have access to a lot of the great electronics stores my USA bros do. 

Any help greatly appreciated,




3 years ago

Hey your motor ebay link is lame.

Why don't you describe the motor.

Is it a DC gear motor or a toy ?

What voltage ?

What RPM ?

What load current ?


Rated Voltage?12V
Rated Current:2.2A
Maximum pressure:0.45Mpa
Flowing Rate:2.9L/Min
Package Size: 19*13*9.5cm
Weight: 0.716Kgs

that any good?

Here is a DIY speed control for your RV pump which can certainly handle the current load of your pump motor.

More details are available at


to teach you how build this very simple speed control.

Be aware at low speed your motor may overheat if you don't have a fluid pressure cut out ie turn off of the pump 12 volts DC until the pressure drops below the needed pressure.

Happy Building


You need a simple speed contrroler. Here are a few Ebay links...




If you want to build your own there a few way to go about it... Do you have any interest in learning to program a micro controller like an Arduino?


look up "LM317" schematics in Google. it is an adjustable voltage regulator with lots of documentation ! Unfortunately the lm317 is limited to 1.5A so directly replace it with it's bigger brother the LM1084 (it's a direct replacement) Also this regulator requires a minimum 1.2V more then what will be supplied to the pump. So if you want to run your pump at 12v you need a 13.5V supply(or just run you pump at 10.8 V that should still work fine :)

I did see that earlier, but was a bit worried because it says 10Amps and my pump is 2Amps.. what effect will that have?

Steve's recommendation to you is top notch. Your grounding in electricity is very sparse...... Consider water pressure as voltage and water flow as amps of current.

Now imagine a farmers water tank being used to water a lawn, it would run out of current in a morning BUT if there is a hill lake it could supply current for days.

So a large current supply ability is a desirable quality in a power supply.


10 A is a MAXIMUM current it can supply, it will be fine here, running on only 2.

To control the flow, a flow regulating valve is probably the easiest, regardless of the pump you have

I have done that before, but I think it burned my last pump out - hence why this time I want to control the motor speed..