This circuit produces pulses of 90 V at intervals that can reach 5 minutes. The circuit is from a 1969s Electronic Design.
This receiver with two common JFETs was found in an old English documentation. The phone is...
This TTL circuit with the 7493 makes the binary count of the pulses sent by a flip-flop with the...
This circuit was found in a Popular Electronics from the 90s. The counter circuit is not common...