I can think of a few problems:

1. You'd probably need a Hi-Fi VCR to preserve dynamic range, unless you 
rigged up some companding scheme like an old DBX to use the analog tracks.

2. Consumer VCRs aren't built for continuous duty, so you'd likely 
encounter high down-time and maintenance cost with older units. 
Professional VCRs used for surveillance and time-lapse video costs more 
than a high end computer system.

3. You wouldn't want more than 20 passes on a high quality tape, so costs 
of consumables will eventually become a factor.

Might be easier to use an old computer and sound card with some 
mod-demodulation scheme.

Michael

At 02:12 PM 7/4/01 -0700, you wrote:
>         Has anyone thought of using a VCR's audio input to record up to
>six hours of a tone modulated seismic signal ?  A person could use two
>old VCR's on timers to give  twelve hours of recording at a time
>and when an event occurs, you got it on tape to digitize and save.
>         Just a thought.

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