This two-output circuit was found in General Electric documentation from the 1990s. The circuit uses an NTC as a sensor and the control element is an SCR.
We found this good power amplifier with the LM12 integrated circuit in the March 1989 issue of...
This simple circuit produces a tone when triggered by any vibration picked up by the sensor. The...
This circuit was published in an English magazine from 1980. The magazine no longer exists, but...