The transistors of this circuit found in a 1965 magazine can be the BC558 and the sensitive 12 V x 50 mA relay. The other components are common.
The traditional circuit was taken from a French magazine Radio Plans that no longer exists but can...
This monostable circuit, from a 1977 Radio Shack documentation, uses a 7400. The time is given by the...
The circuit shown in the figure activates a small indicator lamp that will start to flash when the...