Found in an EDN from the 1980s, this circuit uses a double 555. The circuit activates a relay that controls a horn or siren. Next to the diagram we have the timings.
This small signal injector generator was found in the February 1971 issue of Radio Electronics magazine....
This amplifier, found in a 1981 publication, provides 15 W lHF power with a supply voltage of 14.4...
This simple passage alarm is powered by the power grid using an LDR as a sensor. The circuit is...