I have a circuit using a NPN transistor with a motor before it and a pwm into the base.
The motors draws a current of 600mA if I plug it directly into the power source, just under the maximum allowed by the transistor at 650mA.
The minimum gain of the transistor is listed at 100, with my multimeter reading about 200. The voltage is at 3.7V.
My question is, if I give a base current of lets say 20mA, even with the minimum gain, it is 2A, but will this current be limited by that the motor draws (600mA), or will it push 2A onto the motor?
I have blown 2 of these transistors already, but connecting the base directly to 3.7V. The transistor in question is 2N2222A in the metal case.
Another question is for a simple LED circuit switched by a transistor, is it Ok to depend on the hfe alone? For example, I only have a resistor connected to the base with the collector to HIGH and emitter to the LED?