[EE] Speaker-level to condenser-mic level/impedance conversion?

[Neil]

Hi all,

I want to take the output of a baby monitor receiver (which has a small
built-in speaker), and send the output to the input of a device that
uses and electret/condenser mic (a Velleman MK171 voice changer),
instead of the speaker.
I can use a votlage divider to attenuate the signal, but what would I
need to do about the impedance to minimize distortion?

Cheers,
-Neil.

[Bob Blick]

Hi Neil,

You don't need to worry about the impedance, but the ground point that you use might be critical to minimize noise. I wouldn't rely on the baby monitor's PCB designers to have taken care as to the loudspeaker ground, and running it to a separate device with high gain will amplify any of their poor layout choices. So be prepared to try different spots on the board to tie your audio ground.

Best regards, Bob

________________________________________
From: piclist-***@mit.edu <piclist-***@mit.edu> on behalf of Neil
Sent: Monday, August 20, 2018 8:56 AM
To: Microcontroller discussion list - Public.
Subject: [EE] Speaker-level to condenser-mic level/impedance conversion?

Hi all,

I want to take the output of a baby monitor receiver (which has a small
built-in speaker), and send the output to the input of a device that
uses and electret/condenser mic (a Velleman MK171 voice changer),
instead of the speaker.
I can use a votlage divider to attenuate the signal, but what would I
need to do about the impedance to minimize distortion?

Cheers,
-Neil.

[Jean-Paul Louis]

You could use a simple transformer to break any ground loop between the receiver and the microphone input.

Just a thought.

Post by Neil
Hi all,
I want to take the output of a baby monitor receiver (which has a small
built-in speaker), and send the output to the input of a device that
uses and electret/condenser mic (a Velleman MK171 voice changer),
instead of the speaker.
I can use a votlage divider to attenuate the signal, but what would I
need to do about the impedance to minimize distortion?
Cheers,
-Neil.
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Just my $0.02,

Jean-Paul
N1JPL