Found in a Hands On Electronics from the 80's, this circuit activates a relay with alternating touches on the push-button. The relay depends on the supply voltage.
This timer with 1 second accuracy was obtained in a 1973 documentation. The Buzzer is a low-power type...
The sensors in this circuit are NTCs and PTCs that work in a differential way by directly...
The presented circuit is suggested by Texas Instruments (www.ti.com) in its Application Report...