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How to Convert Speed to Power in a DC Motor? Answered

I need power from my small DC motor, not speed.
I have a few small DC motors that run like wild, they have speed, but what I need from them is to run very slowly, about 1 revolution per 4-5 seconds, but I need it to have power, power to lift something...that something isn't to heavy...
My point is they need to go slow, very slow, but to have a bit more power.
How do I convert Speed from a DC motor to Power ???

Thank you!



Cheap drills have excellent gearing in them with no need to modify much. Usually just file a flat side into the motor's shaft.

Use heavy things to make the motor slow.

lol thats just called burning out the motor.... or in terms you can understand "making it NOT work"

That won't convert speed to power.

Gear it...small gear on the motor, large gear to the load. changes speed to torque. visa versa changes torque to speed so using a large ratio (N<

I think what you need is a pulley with variable amounts of speed, here is a schematic:


Almost anything in the world can be reversed, and I know for a fact that motors can too. No need for a gearbox, if you turn the axle, then the motor will generate as much energy as it would have taken to move the axle with elecricity. Even if you have it attached to a gearbox, it would still only generate as much energy as without a gearbox. All the gearbox does is sacrafice some torque for speed. In that respect, the motor will turn faster, but it will be harder to turn the axle.

To convert speed to power (and vice-versa), you will need what is called a gearbox. The speedy end of the gearbox (the smaller gear/the worm gear) is connected to the motor. The powerful end of the gearbox id connected to....well, whatever you want. Worm gears provide only one-way speed to power conversion however, and reversing this could damage your motor/gearbox...

small gear on the motor and large gear on the other thing small wheel on the motor and large wheel on the other thing and plastic band between them the relation between gear sizes is the relation between forces and reverse to the relation between speeds

Hmm, so this is a mechanical way with gears... Cool, that sounds like a good idea and I would probably use something like this on this project. I need the motor to turn on for lets say 5-6 seconds and turn off and stay in that position.... It has to turn a pole or what ever and lift a small panel....

the control should be with feedback - sensor that feels where the panel is and switches the motor without it the motor will stop each time at a bit another place and after some runs stop the panel away from where it should be a sensor can be anything like led and photodiode or small mechanical contacts if you still want blind control then you should use stepper motor. they usually have more torque than the small dc motors if you use mains ac power use the motor that spins the dish from an old microwave

I want to use DC power... And I like your plan with the feedback...but how can I do that...you are totally right about the blind control. Can you come on MSN tomorrow at about 11:30 or 22:00, so we can discus? Thanks!

i am on msn right now but you dont respond. something goes on with your msn

That is one way, or the other way is to use a gear motor. Here are two examples from a site called allelectronics.com. It has good prices and a good selection. Good places to find gear motors are in moving devices or old video cameras (they power the zoom). Gear motors also have a lot more torque.


I looked at the site, the site is pretty cool! Has lots of good stuff! I looked at the motors and the only one I saw, gear motor, has 5 revolutions per minute, witch I think is some where ideal for me... Because it has to lift a panel just for an angle that is close to 180 degrees... Now the other thing is how to control it, I need it to run for 5-6 seconds and stop, and remain in that position... The motor has to be triggered by light...so when light hits the LDR the motor turns on for 5-6 seconds and when light disappears the motor goes back to its original position... Also, I couldn't find this but does this store sell to Europe, particularly Serbia??? Thanks!

I believe they deliver world-wide. It may cost a little more than the standard $7 for shipping. I am not completely familiar with LDRs. I know the general Idea, but do they cause more resistance when light hits them, or less? The simplest way to build your circuit that I can think of without using a servo and micro controller would be using a relay and capacitor as the base circuit. Without thinking for a bit, I'm not quit sure how to do this, but somehow make it so that when light is present, a relay is flipped to allow electricity to flow to the motor. A larger value capacitor could be used to keep the relay closed, or you could use a smaller one to keep the circuit from constantly flipping back and forth if the light doesn't stay perfectly constant.

I did think of one way to do it. If your LDR increases resistance when it is exposed to light, then just put that on the voltage line that controls the relay. Therefore, when it is exposed to light, a normally open relay will be open since the voltage is not enough to flip it, and this will allow voltage to flow to the motor. When the LDR is not exposed to light, the relay will flip back to a closed position because the LDR will not be putting as much resistance into the circuit. This is all depending that the LDR will gain resistance when exposed to light. Have you had a chance to test whether it gains or loses resistance when exposed to light?

Unfortunately I haven't had the chance to test it yet... Currently I am working on the cube that has to have sides that open... It is not that easy as you might think... I only want to use 1 motor and for now the test aren't so good... I made a model from cardboard but it is not that good... I will make one from plexsy galls and see than what... I need a system that opens 4 sides of the cube for 90 degrees.... Do you have any idea how that can be achieved easily??? Thanks!

Printer motors work really well.

I found a DC motor and worm-gear in a video recorder (load-eject) If you can find one it may be useful? L

Yea, or maybe an old cassette player... It has a motor and a belt that is connected to a wheel and rotates it, although it may be to fast... :P

The belt is a weakness and audio cassette motors are not designed for much torque. Electric car window motors are fairly slow & powerful, also wiper motors. L

Yea... but for a project that I am curently making, I don't need that much power... but the question that I posted interested me in general...

use a better motor, from a VHS recorder