This design allows to operate two intercom stations leaving the operator free of using his/her hands in some other occupation, thus avoiding the usual “push-to-talk” operation mode.
No complex changeover switching is required: the two units are connected together by means of a thin screened cable.
As both microphones and loudspeakers are always in operation, a special [...]
The complete circuit is shown in the diagram and is formed by a microphone amplifier built around IC1A, a simple ac-dc converter (IC1B and related components) driving the dual electronic switch (IC2A and IC2B) and a headphone amplifier formed by Q1 - Q6 etc. For this amplifier only the left channel is shown: obviously, the [...]
For the first time, this circuit was designed by two authors, Mr Laurier Gendron of Burnaby in British Columbia, Canada, and myself. Please make sure you visit Laurier’s web site, Handy Dandy Little Circuits. This page is also available in French by clicking on the flag.
In this doorphone circuit,an 8 ohm speaker is used both [...]
Obsession Theme by Lorelei. Coded by Cheap web hosting and Hostmonster.
Featuring Liza Kliko's artwork in the header.
