Speaker as Microphone Circuit
Budget: $10 – $30 USD
We need a professional (ideally field proven) circuit/schematic on how to use a typical ceiling speaker (8 Ohm NOT 70/100V) for talkback/intercom purpose.
Of course, ideally the switchover between amplifier output and room audio amplification circuit is done electronically, but i am even willing to use a relay for that. I guess you can image what this will be for - a device which will use a ceiling speaker, normally operated as output, also for intercom/talkback/listen-in functionality.
To make this clear - i do not need someone who thinks he might have an idea, and come back with some schematic from an internet source, or a standard LM386 saying 'the speaker will work like a mic'. I need a professional, proven, low noise circuit which adapts to the specifics of the speaker so the audio picked up is clear and clean. Wire length between speaker and device will be max. 3'' (1m), unshielded standard speaker cable.
Of course, ideally the switchover between amplifier output and room audio amplification circuit is done electronically, but i am even willing to use a relay for that. I guess you can image what this will be for - a device which will use a ceiling speaker, normally operated as output, also for intercom/talkback/listen-in functionality.
To make this clear - i do not need someone who thinks he might have an idea, and come back with some schematic from an internet source, or a standard LM386 saying 'the speaker will work like a mic'. I need a professional, proven, low noise circuit which adapts to the specifics of the speaker so the audio picked up is clear and clean. Wire length between speaker and device will be max. 3'' (1m), unshielded standard speaker cable.