Creatrope built an automated VHS tape eraser… – “I bought a $15 Radio Shack Video Bulk Eraser from Ebay and learned that it was far too much effort to get the signal off the tapes I tested. I could make the tape unpleasant to watch and static-y, but even a minute or two of bulk erasing wasn’t enough. The signal was still viewable and audio crisp. The bulk eraser had a duty cycle of about a minute or two on to ten minutes off. I needed automation. I have no pretense that anyone will build the same device I built, but it was a fun hour hack to think about the problem. To get a thorough erasure, what I needed was a way to move the tape back and forth many times in front of the eraser and power cycle the eraser to avoid leaving it powered on too long. What could do that? A record player? Long since gone… A pendulum? It would probably stop before the tape was erased. So I grabbed my son’s K-NEX and built this… “ – Link.