Analog Modulator for Video Camera?

Sub-audio? Less than 10 Hz? So, you want to record and play back a sound or just any old signal?

I'd say that depends on the sensitivity of your camera and whatever you use to reproduce the output of the camera.

free online audio equalizer software download - Softonic

More information would be helpful. What is the voltage and drive impedance of the signal. If it is not a problem then what is this signal.

What is the reason you want to use a video camera? This sounds like a traditional A/D record and D/A playback operation. With the information provided the use of a video camera does not make sense.

I don't think there is anything available off the shelf, or if it is even possible to recover below 20hz in the infrasound range....but you can take a look at this for inspiration...

http://news.mit.edu/2014/algorithm-recovers-speech-from-vibrations-0804

http://www.ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20080034649.pdf

The goal is to record some video of a car while capturing accelerometer data. Then play the video and acceleration back into a simulator where the accelerometer data is converted back into physical motion. The signal is in the 0-100 hz range, 2.5v peak. I can certainly do this by AM modulating a 5khz sine wave and feeding that into the mic input of the camera, and on playback amplify, rectify and low pass filter the camera audio output. I'm just curious if anyone has an OTS solution.

You're probably better off using a modulated carrier, though I think 5kHz is a bit high. The problem is that you don't know the characteristics of the camcorder's audio circuitry, its frequency response, cutoff frequencies, etc., especially as you get to zero Hz where there's probably a blocking capacitor that will integrate the signal and cause nonlinearities.

5 KHz is just a for instance. And the fact that I don't know the characteristics of the camcorder's audio circuitry is why I'm hoping someone has solved this problem already. Zero Hz shouldn't be a problem with an amplitude modulated signal.

Can't you create a video of the accelerometer data with an old silly scope?

An oscilloscope built into the dash would be nice.

I don't want to make a video of the accelerometer data, I want to record video of the car driving, and record accelerometer data at the same time, so I can play them back together.

Found this....

https://www.google.com/patents/US3830968

That would work fine. I'm just trying to avoid "me" doing any of it. I was hoping someone sold a little box that connected to a video camera and I could buy it and be done. Maybe there's an unfilled market niche here.

Try Google, "voltage to frequency converters."

http://www.ebay.com/itm/like/261530335132?lpid=82&chn=ps&ul_noapp=true

Thanks, that looks like just the thing.

Just check that the input frequency response will handle 100Hz.

You might have to ask the seller.

Yeah, I'm not having much luck getting detailed specs. They're cheap enough that I'll probably just buy some and then look up the parts.