This circuit was found in the September 1992 issue of Radio Electronics magazine. The circuit does not use a transistor to drive the relay and has no adjustments.
The circuit shown in Figure bellow generates frequencies of 50 Hz, 100 Hz, and 200 Hz. The circuit uses a...
This circuit rejects frequencies around 1 kHz and can be adjusted using C1. Equivalent operational...
From stereo inputs, this circuit generates a modulated and multiplexed signal to be transmitted in the FM...