With a wave of the hand, turn on a USB powered touch-switch LED Lamp. You do not have to actually touch the sensor. It is so sensitive, it will activate by the presence of a finger an inch or two away. While the circuit described here is shown activating an LED Lamp, with the addition of a relay, it can be used to activate almost any electronic device when you turn on your PC.
This instructable also details how to make functional curved circuit boards that can serve as a case and a circuit.
It also shows a fast, easy and inexpensive way to etch patterns and solder able traces on any simple circuit board.
The video shows how the lamp is turned on and off.
The intro Pic shows the touch switch lamp on the left and some other etched curved circuit boards that await components.
This instructable also details how to make functional curved circuit boards that can serve as a case and a circuit.
It also shows a fast, easy and inexpensive way to etch patterns and solder able traces on any simple circuit board.
The video shows how the lamp is turned on and off.
The intro Pic shows the touch switch lamp on the left and some other etched curved circuit boards that await components.
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Signing UpStep 1: How It Works
The touch switch circuit is based on the QT-113 integrated circuit. It works by detecting changes in capacitance. When it is first turned on it measures capacitance at its sensor plate. When a human touches or comes near to the metal sensor plate the capacitance is changed and the circuit turns on.
The sensitivity is adjustable so that at a lower setting it will require you to directly touch the sensor plate. At its most sensitive setting, it will detect your finger through paper, plastic, glass, or even a brick.
The larger the sensor plate the more sensitive the switch. The sensor plate is the triangular circuit board at the front bottom of the lamp.
The sensitivity is adjustable so that at a lower setting it will require you to directly touch the sensor plate. At its most sensitive setting, it will detect your finger through paper, plastic, glass, or even a brick.
The larger the sensor plate the more sensitive the switch. The sensor plate is the triangular circuit board at the front bottom of the lamp.
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It appears that the qt113 is now only available in quantities of 4000 or more.
As of now, you can still get the qt100 in small quantities. I finally got a chance to try one out and it is as sensitive as the qt113 and works fine. You can get a sot23-6 version here: http://www.saelig.com/IC3/IC3029.htm
jeff-o is right. You will have to add an additional circuit such as a microcontroller or another toggle circuit to keep the lamp on as the qt100 does not latch on and off.
Thanks for the inspiration!
Cheers!!
http://ics.nxp.com/products/pcf/datasheet/pcf8883.pdf
$2.48 on digikey.... Going to test it out
reecesrcool - Sorry it's many months before commenting, but just saw this. You have a great idea in theory and I do believe you could make it work. Just a couple of cautions that you may have already considered. Whenever you go to the work of putting something under the floor you want to test it oh so very thoroughly before tearing into the floor. To avoid embarrassing anyone, let's just say I've heard that's the case. Secondly, this actually takes a bit of inventive programming and possibly more hardware than originally planned to come up with the right combination of sensors and a reliable algorithm to tell whether EVERYBODY is out of the room yet before turning off the lights. For example, was that 1 person who entered, or 2 side-by-side? Best of luck if you tackle it.