Found in a 1980s German publication, this circuit tests batteries by type. The circuit is based on a range of LEDs of different colors and is given a table with indications for various voltage ranges.
Found in a 1967 RCA manual, this circuit uses components from the era that can be replaced by modern...
The voltage gain of this DC amplifier is 100 times, given by the relationship between R2 and R1....
This excellent 30 W tube amplifier appeared in the April 1963 Radio Electronics magazine that...