Electric OU: MOSFETs… How do they WORK? Part 7: Basic feedback loop
A negative temperature coefficient (NTC) thermistor is used to provide a variable resistance path to ground for the IRFPG50’s gate charge. Then, the heat output of the mosfet’s load bulb is used to warm the thermistor. The brightness of the bulb thus regulates itself, based on how much of its heat is “seen” by the NTC thermistor. As the thermistor gets warmer, its resistance decreases, allowing the gate charge to bleed away faster, constricting the drain-source channel and raising the resistance of the mosfet, thus dimming and cooling the bulb. An equilibrium is quickly reached. I think it is plain that, if there was a sufficient time delay in the response of the thermistor, this system would oscillate. Slowly. Why am I using the expensive, high-voltage, high Rdss mosfet like the IRFPG50 for these demonstrations? Because this is the type of mosfet that Rosemary Ainslie uses in her claimed overunity device… without the most basic understanding of how a mosfet works and is commonly used. I am hoping that these videos, and the Capacitor and Function Generator videos, will demonstrate to her that her applecart is full of rotten apples and needs to be upset, in order that fresh and wholesome fruit may be acquired.