This circuit operates with frequencies from 0.5 to 400 MHz. We find it in a 90’s NASA documentation. The transistors are from that time.
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...