This circuit of a 1964 Electronic Design uses a photodiode from the time. Modern equivalent can be used. The standby current is 1.2 mA.
We found this circuit in a 1991s PE Hobbyst Handbook. The circuit fires 10 LEDs that can control...
The circuit shown is an amplifier for medium impedance headphones including bass and treble...
In a voltage follower the voltage gain is unity. The input impedance is high and the output...