Photo of USTDC courtesy of Les Duffin

Thursday, May 29, 2008

Camera Obscura and the Knife Switch

Sounds like a good name for a rock group, doesn't it?

Actually, the camera obscura was an early ancestor of the camera. While at USTDC, Sarj Bloom decided to make one, using a shoe box for the housing, and he used it to take this picture of one of the photo lab guys. The negative image is at the top and the positive image is below it. It's a little grainy but remarkably good considering what he was working with.

But what really caught my attention in this picture was the knife switch located on the wall, below and to the right of the air conditioner. I had the same setup for the air conditioner in my office at TDC as well as in my room at the hostel. I often saw them at other locations around town.

About the only time you'll ever see one of those today is in big industrial applications (e.g. Dr. Frankenstein's laboratory) or in school science projects where you want to control the current from a battery to some small electrical gadget. They're considered way too dangerous for normal applications.

They had a porcelain handle for toggling the switch up or down, but everything else was exposed metal, including the wiring. I used these switches to turn the air conditioners on and off and I was always fearful that I'd brush up against the hot contact and get fried right on the spot.

I somehow survived the knife switches and I trust that nobody in Taiwan is using them today.


Anonymous said...

There are plenty of those old "knife switches" around. I saw one in a bathroom recently for a small electric water heater.

Don said...

Yikes! I can't believe that they're still being used anywhere!

Sarj Bloom (former Navy guy) said that the Navy installed those switches all over the compound just to scare us Air Force types.