This circuit was found in the August 1971 Radio Electronics magazine. The SCR admits equivalents and instead of the buzzer a sensitive relay can be used.
An oscillator whose frequency can be adjusted between 500 Hz and 5 kHz with the use of a...
This circuit was found in Motorola documentation from 1969. The transistors are from that time. The...
This circuit brings together in a single set a preamplifier and an equalizer with several inputs. The...