This audio oscillator is from a 1957 Raytheon publication. The tone generated depends on C2 and C2 and the handset must be high-impedance magnetic. Equivalent transistors can be tested.
This circuit converts sinusoidal signals into squares and can be powered by voltages from 1.5 to 5...
Found in a 1969 Electronic Design, this circuit is intended to power a load up to 300 mA....
This amplifier was published in the July 1961 Radio Electronics magazine. It announced the release of...