This alarm siren circuit has a latch. We found it in an article in the January 1975 Radio Electronics magazine. Note the power given by Rx and the speaker. It can be increased by changing Q1.
This is the traditional configuration of an inverter amplifier with operational. The operational...
In the figure we show how to implement a voltage-controlled oscillator. The circuit is from Texas...
Found in a 1967 American publication, this circuit with feedback for two transistors has a gain of...