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 source is suitable for low consumption equipment that uses batteries. The circuit is...
This interesting circuit was found in an Argentinean Radio Chassis Television magazine from March...
This circuit is from an 80's documentation, firing when the input voltage exceeds 5 V. The SCR can...