This 2-tube amplifier was found in a Japanese publication of 1964. The circuit has excellent sound quality. The power supply is not given and must provide a voltage of 300 V.
The operational amplifier is old. The circuit is from an 80's documentation but can be designed...
The connection of high-value input resistors causes the circuit to behave like a conventional...
We find this encoding circuit in an American 1980s amateur radio documentation. The circuit can be...