The transistor can turn on or off if the base current turns on or off ... Connect a circuit using wire, a 9-V battery, an LED, a resistor, and a microammeter to measure current.

The base resistor chain from the bipolar circuit ... and noted that while its mode of operation is different to that of a bipolar transistor it does a substantially similar job.

See the R1 resistor in the intro circuit ... it uses an unorthodox driving circuit – it has an NPN transistor, but its base driven through a capacitor, so that only the AC component of the ...