Hi! And thanks for answering!!! Ok I removed the resistor between the out put of the hall sensor to the npn, and changed the 560k resistor with a 10k resistor on the supply of the npn as advice, the circuit works... I will measure the volts and the ahpere that I get to the coil. My coil is made by approx 100 turns 1mm wire and the core is about 2cm diameter 4 h in soft iron... it's ok but will be better if I can get more rotational speed. any idea how to make a better one? I heard that twisted wire works better.

 

Hi, I connected 2 coils in parallel,to the circuit I fried the mosfet I think... the power stay on and does not switch... any idea? Lol

 

Just confirming that the mosfet need to be replaced I've continuity between the drain end source. In using one coil was all good as I connected the second in parallel ++ --
It fried the mosfet. should I conect them in series +-+- ? Thanks! I'll doble check the second coil but I went in the same direction with the wire as the previous one,

 

Just confirming that the mosfet need to be replaced I've continuity between the drain end source. In using one coil was all good as I connected the second in parallel ++ --
It fried the mosfet. should I conect them in series +-+- ? Thanks! I'll doble check the second coil but I went in the same direction with the wire as the previous one,

Adding a second coil in parallel would double the average through the MOSFET. Without knowing how much amperage you were pulling in the first place, we don't know if that should've been a safe move or not.

I'd suggest you replace the MOSFET, then retest the circuit with just one coil again. Assuming it's working again at that point, measure the gate voltage, measure the voltage across the motor, measure the MOSFET drain-source voltage drop, and measure the current through the motor.

With these measurements, we'll know if the MOSFET is being driven properly into saturation, as well as how much power the MOSFET is dissipating. This information will help determine if you can safely drive a second coil from the same circuit.