This current boosting circuit uses an op-amp and 3 transistors. The current depends on Q1. The circuit is from the 1995 Encyclopedia of Electronic Circuits Volume 5.
The FAN1117A and FAN1117A-5 integrated circuits from Fairchild consist of fixed and adjustable...
This transmitter uses an electret microphone and has a few tens of meters in range. The coil L1 is...
We found this circuit in the November 1995 Electronics Now magazine. The circuit is more accurate than...