This circuit for audio signals was found in the March 1990 Radio Electronics magazine. The circuit uses a unusual optocoupler that can be replaced with an equivalent one.
The filter shown in the figure can have its cutoff frequency adjusted between 2 kHz and...
This circuit, which uses a quadruple comparator, was found in old American documentation. The...
This shield for controlling the direction of rotation of DC motors up to 500 mA with BD135 / 6 and...