well i was using the FQA30n40 fet witch is about a 400v 30 or so amp fet, i used this to run the stator on an alternator from around 2 to 8 amps, witch i hardly ever use 8 amps. it stoped working like all the others over a period of time.
i was using a 555 timer to pulse the fet to regulate the needed output to the stator, but i soon seen i did not need pulses that i could make the circuit smaller by just regulating the voltage and amperage, with 1 to 2 amps is ideal.
so my good fet is now dead.
i have 5 irf640's laying around.
what i have done, i have taken a 3 pin pot and added 2 100 ohm resistors on the outer side of the 50k pot, i hooked the gate of the irf640 to the center of the pot.
ground the source of the fet, and the rotor goes between the Drain and + side of the battery.
i turn the pot and read that i am pulling .40 amps with the stator and the fet starts to heat up, if i go to .70 amps it will burn my finger and i cut it off.
so why is this 18 amp fet or so not handling this small 1 amp? i do not know.
i have seen a circuit from **broken link removed**
they say it can produce 15 amps, man i've blowed many of those at just .70 amps, i don't understand how everyone is getting all these amps outta these chips when i cant?