This sonic relay circuit is driven by a high-pitched sound picked up by a microphone that can be a low-impedance tweeter. The transistors support equivalents. We found it in a Radio Electronics magazine from September 1969.
This sonic relay circuit is driven by a high-pitched sound picked up by a microphone that can be a low-impedance tweeter. The transistors support equivalents. We found it in a Radio Electronics magazine from September 1969.