This old 4-channel circuit was found in the December 1994 Electronics Now magazine. The circuit uses a 556 as a modulator. Note the code programming key.
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...