DC Motor Speed Controller PWM 0-100% 400Hz – 3khz Freq

This is the best cheapest DC motor speed controller circuit that you can find on internet.
In the past i tried wit NE555 and other circuits but the results were every time in shorted mosfet`s and not stoppable GO KART (not very good thing when you do not have a big red kill switch).
In in the following i will  present my DC Motor speed controller capable of adjusting speed (PWM)  form 0 – 100% and the frequency form  ~ 400Hz to 3kHz, based on LM339 comparator.
The power supply is from 14-30volts,  expandable to practical any value with little modification.
From R15 VR 10k you can adjust the speed from 0 -100%
From R14 VR 100k you can adjust the frequency.
If the jumper JP1 is shorted you can adjust the PWM frequency from 400Hz  to 3kHz. If jumper is open Freq is fixed at 100Hz.
The circuit is designed in Eagle cad 6.2

You can use almost any Channel N mosfet`s you want. The fets will be mounted on a radiator if the current is  higher than 2-5 amp.
It is possible to increase the voltage supply to any value if you separate the power to the logic circuit from power to the load and mosfet`s
This is my second prototype of dc motor controller


Depending on Rds ON value of the mosfet`s you will need a smaller or bigger radiator.
The wires will be at least 12 AWG for a 30 -35  amp load.
For any questions you can  ask me any time via my e-mail found on about menu.
Success with the circuit.