Found in a 1924 documentation, this circuit is powered by 3 batteries, two of which are high voltage. The output is a high impedance headphone jack.
This circuit can source up to 1,000 V from a 9 V battery. Output current is very low, some...
The National Semiconductor LM675 operational amplifier can provide up to 3 A of output current. In the...
This circuit is for traditional old-style telephone lines found in an American 1980s...