We found this circuit in an American documentation from the 1990s. The circuit is based on the LM3909, a low power oscillator from National Semiconductor.
This transmitter kicks in when the microphone picks up sound. This sound then modulates the signal...
The great advantage of the circuit shown in the figure is the fact that its frequency is...
This circuit for incandescent lamps was found in the February 1972 Radio Electronics magazine. The triac is...