Found in a Philips' 1968 documentation, this circuit is slightly different from the previous one. The components are also from the era, and modern equivalents can be used.
Radio Electronics magazine published in a 90's issue this simple alarm that can use any general...
This circuit is from the 2005 Linear Technology Application Manual. The circuit must be powered by 5...
We found this circuit in a 1969 General Electric documentation. The circuit uses transistors of the...