I am a student trying to build a simple permanent magnet brushless DC motor but is having problem getting a commutation circuit diagram i dont want to use IC. can anybody help me with a simple and working commutation circuit diagram? any position sensor is okay by me. thanks.

 

i dont want to use IC

well then you are going to be stuck generating 2 or 3 phase timing chain, zero crossing detector, back EMF detector and/or a PID loop to connect it all together with discrete components, and there aren't that many good schematics available, for the same reason why its hard to get a good schematic for a SCR based chopper. nobody uses them anymore...

or you could take a look at the nearest hard drive and down load the datasheet on the motor controller..

you might want to find the oldest computer fan you can possibly find, all the new ones have an integrated controler, there are some creative 2 phase circuits that require a minimum of parts, but they don't have any form of speed control.