This siren configuration found in a documentation from the 1980s can also be seen in many of our projects and in this circuit bank. Transistors are common, but Q2 can be of power for a higher voltage supply.
Crystals from 100 kHz to 1 MHz can be used in this 1957 Raytheon circuit. 4 can have values...
Assembled with SMD components this circuit can be very small. The range is a few tens of meters. We...
This circuit can provide a voltage of up to 900 V depending on the input voltage. The diodes must...