Found in an Electronic Design and 1970s, this circuit uses transistors of the time. The transistors can be replaced with equivalents and the relay is 12 V depending on the power supply.
This 90's Electronic Design circuit converts the period of a signal into a frequency. The...
This Radio Electronics circuit, in an 80's edition, decodes the 67 kHz signal used at the time to...
This logic circuit can indicate both TTL (5 V) and CMOS (5 to 12 V) output levels, operating with...