In the figure we have one of the many options found in this section for an intercom using ordinary phones not in use. This was obtained in a Popular Electronics from the 90s.
This analog ammeter circuit was found in documentation from the 1980s. The components admit...
This conventional Hartley oscillator circuit with an audio output transformer was found in a...
This bar or moving point indicator (bargraph) employs the LM3914 and can excite 10 LEDs, of any...