Monday, September 28, 2009

ON and OFF

Do you think Edison used a switch in his experiments? And if so, what did it look like? My guess is that he used a toggle switch – the old-fashioned kind with a big handle, mounted on a sturdy wooden board to keep all the components in place. For some time now, I’ve been toying with the idea of writing a series of articles or a small book on switches and clever ways to turn devices on and off. Everything from simple switches to light switches, low-voltage and high-voltage switches, transistors as switches, switching equipment partially off in the standby state, mercury switches (now forbidden) for detecting motion, and how you can use physical phenomena such as speech, pressure, motion, height differences, water, light, fire, and so on to activate a switch.

I’m writing this during the Elektor presence at the ESC show in Boston. There we meet a lot of good folks, and they visit our booth to show us all sorts of things. Consider the man in the photo: while watching a screen from the corner of his eye, he operates a computer with his voice. He’s called “Golden I.” Naturally, when you’re having a conversation you have to be careful to avoid the voice commands you use to control the computer. Terms such as open, close, file, mail, and so on can confuse the computer and disturb the conversation, or cause the wearer to glance nervously into the little screen. Actually, this is also a sort of switch – I wonder what would happen if you suddenly called out ‘ON’ or ‘OFF’ while standing next to this man? Would his eyes go into standby, or does he also have a screensaver? For his sake, I hope not.

If you know an interesting way to turn something on or off (people, animals, cars, radios, TVs, etc.), you’re more than welcome to send your ideas to

Wisse Hettinga

Readers respons:


This researcher works on ways to control systems with facial expressions. He and his colleagues have developed a way to control an MP3 player with chewing movements and a second system that uses the temple muscles. This last one attracted quite some interest in 2008 on the internet under the name Kome-Kami switch.

A news item in French can be found here:

Clemens - Elektor France



I reflashed a router to a linux server. He is doing my webserver, mails, back-up server tetc.

He knows

- the time (from the internet)

- day and night to switch on the lights

See the developments

P.v.Geens (Holland)


I would think that if Edison used a switch in his experiments and/or apparatus, it would have been a knife switch. In the early part of the century when Edison done most of his work, the knife switch was the most popular type available to both the experimenter and to industry. Therefore, it stands to reason that Edison too would have used this type of switch.
This is my opinion based on my knowledge of Edison's work, and the state of the art of electrical apparatus of the day. If you find that this isn't the case, I will apologize and stand corrected.


Dear Wisse,
Many people overlook diodes as switches. They can be very useful when you want to switch many analog signals at once, as in changing bands in a shortwave radio or changing modes in a transceiver. I've attached an article I found describing diodes as switches.

Best Regards,
Dave Bailey
Technical Support Engineer
IAR Systems Inc.
2 Mount Royal
Marlborough, MA 01752

(article can be dispatched on demand - thanks, WH)

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