This TTL circuit is from a Radio Electronics magazine from February 1973. The circuit must be powered with 5 V and the maximum frequency depends on the TTL integrated circuit.
This simple musical instrument was obtained from a 1967 magazine. If the original transistors are...
The transistor of this circuit can be the BC558. The circuit is from an old documentation...
We found this circuit in an old American documentation for hams. The circuit serves as a telegraph...