Simplest PWM Motor Control Circuit Using Op Amp

Hello People!

This instructable is about how to build the simplest(probably) PWM circuit to control DC Motor speed, LED Strip Brightness, etc.

Specs:

Input Voltage : 5-30v

Current Handling : Depends on the MOSFET(Around 10A for IRFZ44)

Please comment if you tried building it!

Comments

[morton6689]

i could be wrong but shouldn't there be a diode hooked across that motor to protect the MOSFET from back EMF? I realize this is a old post that i came across and doubt ill get a reply but if anyone new to electronics is going to build this i am 98% sure (i am not an expert on this) that you need to hook up a diode across the dc motor. look up snubber diode. when current is stopped the windings in in the motor have built up energy that becomes a voltage spike going backwards through the circuit which can damage (in this case) the MOSFET.

[Usairum Mirza]

it depends upon which load you are using e.g if your load acts like a inductor (stores energy) then yes you need to have a protecting diode

[morton6689]

I thought the diode was there because of the relay coil when closing has a magnetic field that collapses and sends out a spike of energy which travels backwards and can damage the mosfet. I wanted to look at the circuit again but its not available to me. i didnt know you could make instructables private. why make a instructable and only share it with a few people. knowledge should be shared with everybody that wants to learn.

[vipinckty676]

Nice circuit

[megapix]

Clever circuit. I also like the use of the bottle cap as a control knob.

[BeachsideHank]

What advantages does this circuit posses over the more popular 555 PWM designs?

[Stuff Builder]

Here are two

One advantage might be higher operating voltage and other might be that two individual controllers can be designed using a single IC

[BeachsideHank]

Both are excellent reasons, thanks for the reply!

[DIY Hacks and How Tos]

Nice basic control circuit design.