In use telephone indicator (CB8665E)

This circuit was found in a 90s Electronics Now. The circuit can use a TIC106 for the SCR.

Sinusoidal Oscillator (MSB013E)
This circuit produces low frequency sinusoidal signals. The circuit is a phase shift oscillator...
Speaker Systems for Bench (CB17695E)
This 2009 circuit serves as an aid to those working on audio equipment repairs. With it, the...
1 kHz third order filter (CB12570E)
The circuit shown in the figure is a third order Bessel filter with unit gain using two...