Creatrope

Materials Needed:
* Radio Shack Bulk Eraser
* Linux Box, with Perl & Heyu Installed
* Some K’Nex
* An X-10 Appliance Module
* Large Binder Clip
* Rubber Band
* VHS tapes you want to erase

I decided to clear my house of a lifetime collection of VHS tapes. I had acquired boxes of new and used unmarked VHS tapes at a ’sealed box auction’ at a local moving company ages ago. I’d gone through some of them, lost interest quickly, proceeded to reuse a few and just stored the rest.

I found myself in an interesting position trying to decide whether just to dump them, destroy them, or donate them.

The idea of giving the Salvation Army boxes of tapes that I had no idea what was on them was not particularly appealing, nor was just destroying them (which, in retrospect, would have been the easy route but hard on the conscience ecologically – it’s not unreasonable to assume someone can make use of good quality VHS tapes even in 2006).

Since it’s considered good form to wash clothes before you donate it, I thought it was reasonable to do the same with tapes (that is, erase them).

So 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…

Basically, it’s a frame that implements a conversion from rotary to linear motion. The linear K-NEX segment go through a white piece with the hole which is mounted on the frame, which is reasonably rigid (for a toy). The VHS tape is connected via a rubber band then moves back and forth.
The eraser will be placed sideways next to the tape.

2 AA batteries in the geared motor had no trouble pulling the tape back and forth over a smooth surface (not carpet as pictured…).

My first try to hold the tape was a large steel metal binder clip. It looked a lot cooler than a rubber band and held the tape firmly. Can you guess how well that worked out once the bulk eraser was powered up? Next, I switched to the rubber band.

The final step was to create a duty cycle for the bulk eraser (not pictured), which was placed directly alongside tape. This consumer grade bulk eraser can only stay on briefly and then needs to cool off. I use a large binder clip on the on-off switch to keep it on, then plugged it into an X-10 Appliance module. I controlled the duty cycle on the appliance module with the great little X-10 application, heyu.

#!/usr/bin/perl

while (1) {
system("heyu2 on P15");
sleep(15);
system("heyu2 off P15");
sleep(15);
}

I experimented with various duty cycles, such as 30 seconds on and 1 minute off until I was able to get a reasonably decent erasure. With a little more patience, I have no doubt I could have made the tape completely blank.

Repeat for 100 tapes or until your patience runs out. It’s better than running the eraser by hand (and probably healthier). I found this eraser fairly weak, but it would be ‘best practice’ to keep it far away from magnetic media you actually care about…

In retrospect, popping them one by one into a cheap-o VCR set to record with no incoming signal would likely have done a better job. But not as fun (and not as quick – you’d have to record over the whole tape)

Did I overlook a better way?
Let me know at me @ creatrope.com