The transistors of this circuit found in a 1965 magazine can be the BC558 and the sensitive 12 V x 50 mA relay. The other components are common.
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...