VCR Question

[mblackwell]

My VHS VCR has a tape position indicator feature. I have heard that there is no type of timestamp on VHS tapes so how does this work? I have tried to trick it by switching tapes, but it always estimates the tape position fairly well. Sometimes it takes up to 15 seconds to do this, and it can do it while the tape is playing. I thought it might have an optical sensor, so I covered the windows on the tape with Sharpie marker, it had no effect. So is there some type of time stamp om VHS tapes?

[CurtC]

I just bought a VCR four days ago with this feature. My guess is that it uses the ratio of the turning rates of the spools as a guide. As the one spool gets smaller, it will turn faster, and at the same time, the other spool will get larger and turn slower.

[mblackwell]

Thats a good guess, I bet thats right.

Thanks