I'm trying to record analog values with a digital recorder. Basically I have a recorder and have 2 leads connected via the mic port. If I just apply regular voltage to the leads the recorder doesn't recognize the external mic and records with the internal mic. It seems as though the recorder will only read values through the external mic if there is a tone going through it. I know the Arduino can generate tones, but if possible I'd like to do this with a simple voltage to frequency converter IC like the Texas Instruments LM231 (http://www.ti.com/lit/ds/symlink/lm231.pdf). My question is: if I convert voltage to frequency, is that the same thing as generating a tone (will it be readable)?
What... Tone in a noisy environment??? over long wires? why not RS485?
Even Modems required 30 Db signal to noise, Power not voltage 1 MV noise/volt of signal.
The solution is to disable the other microphone then you can feed whatever you like to the recorder.
An AC signal (tone) being what is required and yes you can record analog data using tones, it was one of the first forms of telemetry.
The only absolute requirement is speed accuracy of the recorder. If the recorder isn't accurate neither will be your recorded data.
I believe if the frequency range of the VCO (Voltage Controlled Oscillator) output is within the frequency range of the recorder, then yes, this should work fine.