motor control

Want more output current? Have a look at 2ctiby's post at; http://everycircuit.com/circuit/5214638451195904

Thanks Billy .... http://everycircuit.com/circuit/4621923149676544

The circuit shown turns the motor current off, a better approach would be to turn the motor current on for the desired time. http://everycircuit.com/circuit/4965755951251456

@BillyT...Your configuration is better (I have altered the note on my adjusted dooperman schematic). It amounts to the same thing however...On mine...If we set the pulse width at 50% then we could say that the gate is being turned on and off equally. If we set it at less than 50% we could say that the gate is mostly on and then switched off. If we set it at more than 50% we could say that the gate is mostly off and then switched on. Yours does exaclty the same but in reverse. Turn my Width up to 90% and you will see that my gate is now like yours (or turn your Width up to be like my present setting).....The main thing is that we now know how to get the pulse width just how we want to alter the gate timing. As an extra bonus, doing that does not effect the voltage....so the volt drop across the mosfet is unaffected which in turn means that such alteration does not change the Rds₍ₒₙ₎ The Rds₍ₒₙ₎ along with voltage and current alterations will also need to be fine tuned along with the above however for more intricate work, and that's when the individual mosfet settings will also be needed. As a side issue....Note your pulse rise and fall settings....they form a triangular pulse at the bjt....that pulse becomes rectangular at the gate due to the on/ off nature of the collector......but if you were not using a bjt whereby you were pulsing the gate directly, then that triangular pulse which is now at the gate may need some attention so as not to throw things astray as per mosfet settings such as set by the gate Vth

@dooperman... nice job...it has given us an interesting circuit to chew over.

my intention is to control PC fans with an MCU. the inversion is intentional to make the fans run full in case of failure