This monostable circuit, from a 1977 Radio Shack documentation, uses a 7400. The time is given by the capacitor and the power must be supplied with 5 V.
This circuit is from an old manual of operational amplifiers. The setting can be adapted to work...
This control panel allows the use of NO and NC sensors, turning the alarm on after 30 seconds...
We found this circuit in a 1977 technical documentation. The FET can be the BF245 and the bipolar...