In the original publication of the 90s a 556 consisting of a double 555 is suggested. The circuit drives a speaker with good power. The power transistor shall be fitted with a heat sink.
This interesting automotive alarm was found in a 90's Popular Electronics. The circuit uses...
Using the 4001 integrated circuit, this latching relay can employ any general-purpose transistor. The...
The PA222 integrated circuit used in this project from an American 1967 documentation is not...