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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.

Step 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.

Step 2: Materials


For etching curved circuit boards:

2 x-acto knives
clear shelf lining from Walmart
Ferric Chloride

12"x12" Thin Scissor cut copper clad fiberglass board from Electronic Goldmine:
http://www.goldmine-elec-products.com/prodinfo.asp?number=G17115


Other items:

Line pattern fiberglass perfboard- Allelectronics:
http://www.allelectronics.com/make-a-store/item/ECS-4/SOLDERABLE-PERF-BOARD-LINE-PATTERN//1.html


QT113 IC from Saelig:
http://www.saelig.com/category/IC3.htm
It appears that the qt113 is now only available in quantities of 4000 or more.

As of now, you can get a similar circuit the QT100 in small quantities. I 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

You will however, have to add an additional circuit such as a microcontroller or another toggle circuit to keep the lamp on as the QT100 senses proximity but does not latch on and off.


2n2222 transistor and leds and resistors from Mouser:
http://www.mouser.com/

Step 3: Making Curved Circuit Boards

Curved circuit boards can be easily made using the very thin circuit board material available at Electronic Goldmine. I have also seen it on EBay. It is copper clad fiberglass that is only .007" thick. It works like any other circuit board except that it is so thin it can be bent and because of the malleable copper cladding on both sides, it will hold its bent shape. It is quite flexible and can even be bent to form a ring that fits a finger. Bend it too much, however, and it will snap like a twig.

The bendable circuit board material can be etched by any conventional circuit board method that you prefer. The method I used for creating a resist is very simple and quick. I took inexpensive clear shelf liner which is sticky on one side and laminated the copper clad board between two layers of the vinyl shelf liner.

I then took a double bladed knife that I made (see pic5) by bolting two exact o blades to the sides of a fiberglass circuit board with the copper etched off. Pic6 shows how I cut out wherever I wanted to etch away the copper. You can cut curved lines or use a ruler to guide the double knife and cut straight lines.

pic7 shows the main body of the lamp laminated with shelf liner before cutting, etching and bending. It is 12" long.

You can of course etch very precise and complex circuit boards. I have chosen to used the curved surfaces to mount LEDs and inputs to create a simple circuit as the main body and structure. The detailed and more intricate part of the circuit is is a fast circuit module made on fiberglass perfboard. See next step.

Step 4: Fast Modular Circuits

I have started making most of my circuits modular so that they plug in and can be reused either on a breadboard or in a new robot. They plug in using .1" headers and sockets.

Pic8 shows the touch module that plugs into the lamp. It is made using fiberglass perfboard from Allelectronics that is the quickest way to make a permanent etched circuit board. You can drill away where you want the traces to end and use jumpers to complete the circuit. Pic9 shows the back of the circuit board where the switch circuit module plugs into the driver transistor board. To keep it thin I use magnet wire for jumpers on the back side of the circuit.

Pic10 shows the bottom of the lamp and the bent circuit board material that is soldered on to prevent it from tipping.

Step 5: Circuit Details

I used a standard USB plug from an old camera. If you cut off the smaller plug which goes to a camera or other device you will find four wires. The black is usually the ground and the red is the +5 volts that USB supplies. Check with a voltmeter to make sure you have the right wires for power. The other two wires are for communicating with the PC and can be ignored.

pic11 shows the details of the circuit. The qt113 drives a 2n2222 NPN transistor which turns on the 5 LEDs which are wired in parallel (pic11b). The base resistor limits the current to the LEDs to less than 100 ma. I used surface mount white LEDs but any white LEDs could be used.

With pins 3 and 4 to ground the switch turns on at first touch and off at second touch. If you connect 3 and 4 to +5 volts the switch will stay on only while you are near or touching the sensor.

I originally etched the back of the 12"  lamp circuit board to be the sensor plate. Because the circuit board is so thin, it created excessive capacitance and did not work. So I did a workaround and mounted the triangular plate at the front base of the lamp.


Step 6: Possibilities


CONTROL OTHER DEVICES
The touch switch is used here to turn on a few LEDs. If you replace the LEDs with a 5 volt relay it could be used to turn on any device that the relay could handle. You could turn on AC or DC devices.

PORTABLE TOUCH SWITCH
While this LED lamp is USB powered, it could also be made more portable by using three aa batteries as the power supply.

CONDUCTIVE FABRIC TOUCH SWITCH
This touch switch circuit is ideal for use in conductive fabric switches where the touch switch plate is a hidden grid of conductive fabric or thread and you only have to touch near or on an area of fabric to turn on a wearable circuit.

LIGHT WEIGHT STRUCTURES
pic12 shows a back lit curved circuit board that has been etched with the same pattern on both sides. Because the circuit board fiberglass is so thin, LEDS can be mounted behind the board and will glow trough. This curved circuit material is ideal for wall lamps or other hanging circuits.

HEAVIER DUTY STRUCTURES
You can make the structures stronger by laminating two bent forms together or gluing a layer of fiberglass on the back with epoxy. Copper wire or other circuit board material can also be soldered to the main structure to make it sturdier.

Hello, I have a question. Can I use the QT100A instead of the QT113?
<br> It appears that the qt113 is now only available in quantities of 4000 or more.<br> <br> 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: <a href="http://www.saelig.com/IC3/IC3029.htm" rel="nofollow">http://www.saelig.com/IC3/IC3029.htm</a><br> <br> 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.<br>
The QT100 would not be a suitable replacement. The QT113 has a &quot;toggle on/off&quot; function, where the output from the QT110 is only active when touched. So, to use the QT100 you'd also need to add something like a flip-flop to toggle the LEDs on and off.
I do not know, I have not been able to try the qt100a. I ordered a couple and they came as a leadless IC about 3mm x 3mm. It is so small, I have so far found it impossible to solder to it.
ohh :s but the QT113 SOIC version it's still available isnt it?
<p>Help!<br>i'm beginner which sensor we are using. and what to do if we connect it with Ac.</p>
<p>i know this article is old and QT-113 has stopped, but is there any other replacement with so low price?</p>
This is awesome! i've made a switch like this once by accident, it was also touchless, i couldn't figure out what is going on :D thanks for sharing
What a brilliant idea! I might make a modification and try to power it wireless using homemade 'Witricity'. <br> <br>Thanks for the inspiration!
Cool!!! Very nice project
this just looks so sick
Both the QT113 and QT100A are obsolete. But the toggle functionality is available in the AT42QT1012-TSHR, available on DigiKey.com for less than $1, part number AT42QT1012-TSHRCT-ND. Enjoy!
Thanks a lot, I was looking for both and couldn't find them anywhere. The AT42QT1012-TSHR looks also very nice with auto power off. :)
Many aplogies for my incompetence, but will this work off of a 12V supply? Or, alternatively, be modified to give out 12V? Looking to drive many (56) LED's - using this as its switching circuit.<br><br>Cheers!!
Looks like an alternative to the IC that this instructable uses:<br>http://ics.nxp.com/products/pcf/datasheet/pcf8883.pdf<br><br>$2.48 on digikey.... Going to test it out
i must say very nice, and with a big enough imagination (which i have) and funds (which i dont have) this could be used for some sort of home automation. considering you dont actually have to touch the metal to control a relay you could lay thin strips of the sensor plate (or if possible just plane wire?) under your floor to detect where you are in your house and when you leave one room turn off all electronics or atleast a light in that room and turn everything on in the next room. it would be a pretty good energy saver for someone with kids who never remember to turn off their lights.... sorry you're ible just sent my brain into overdrive with ideas
mikey77 - great 'ible from both technical and artistic viewpoints as far as the eyes of this beholder see! Thanks!<br><br>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.<br><br>
This is a very elegant and fantastic design. I hope I could also make one out of <a href="http://www.act-cw.com">Printed Circuit Boards</a>.
excuse me, where can i find the curved circuit board, i've been looking for it but i just can't find it
very very nice. what gave you the idea of making such a magnificent piece of work? if you don't mind me asking.
Copper gets ugly if exposed for a long time, specially if someone is touching it regularly or if someone tries to clean it with something wet. So I'd suggest using some kind of spray coating to avoid that.
nice work..congrats
Hi, Is there any other IC that could be used?, Because I cant seem to find the QT113.
I have seen this circuit incorporated in a table saw once. When you finger or any other piece of your body comes near or touches the blade, the blade retracted at a blink of an eye. The inventor was using hot dogs to simulate human flesh. Every time the hot dog touch the spinning blade the blade stopped and retracted instantly. So fast that you could not see the action, and every time the hot dog came away without a mark.
Yea it was n timewarp on discovery
in that case, would a QT118HA-ISG be a viable replacement, I cant find a qt113 that isnt either out of stock, or that you need to call the company to buy it. http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&amp;name=427-1139-1-ND thats the link to the ic
I can't seem to find the IC from a supplier in the UK, and am having trouble finding a replacement. Even the IC you used seems to be obsolete in the states also. Thanks to any who can help :) Very nice instructable by the way, will try and finish it when I can finally get all the parts :P
It is very elegant =D As for the IC Qt113. The circuit can be replaced by a 555 timer with the capacitance change changing the frequency and use a band pass filter to detect the change of frequency to turn on the light.
The Qt113 is not obsolete. I am so sorry that you did not bother to read as far as step 2 where I gave everyone a direct link to where you could buy the QT113. Its true, the Dip version is no longer available, but a SOIC version is available. There are also improved versions of this type of circuit available. While SOIC sized ICs are a little tricky to solder, here is a link to where I have detailed a fairly easy way to solder them: https://www.instructables.com/id/Make-A-Remote-Control-Ring/step4/Picaxe-Microcontroller/
Hello Mikey Excuse me for my english i'm from holland. I wanted to ask you where i can by the touch sensor QT113. And witch one is the best solution for the job? I have searched and found a couple but i dont know if it wil work. Thanks in advance.
I did say 'in the UK' but there you go, the manufacturer's site lists the chip as obsolete. I suppose if this is the only source then I shall have to get it from there. Thanks for the SOIC soldering method by the way, good idea :)
Very nice instructable, I would like to make one, but I haven't found this kind of thin copper clad here in europe yet. You said you saw it on ebay, can you please give me a link, or the name of the seller? Thank you!
Here is one: http://cgi.ebay.com/24-shts-Copper-Clad-Laminate-FR-4-008-4-5-x-8-DS-/310216528371?cmd=ViewItem&amp;pt=LH_DefaultDomain_0&amp;hash=item483a5891f3 If you search ebay for pcb boards or pcb laminates you can find others.
Thank you!!!
well done for winning mate. Well deserved. I saw this and was instantly wowed to the point of thinking of applications that I could use it for. this will be my intro to PIC's I think :)
Hey really love ur design and want to try it out but just a few questions... 1.could you please include a tip, step or instructions of any kind on how exactly to mount the circuits to the bendable board 2. and another angle shot of the triangular mount to the lamp so we can see how it is done...
The circuit board is mounted to the lamp body with two 22 gauge solid wires which are stiff enough to hold it in place when soldered to the front copper traces that go to the LEDs. A third solid insulated wire goes through a hole in the lamp body to the front triangular sensor board. It is longer than necessary to allow adjustment of the sensor plate. You can see the solder joint at the bottom front of the triangular sensor.
Just want to know, do you have to torch the switch to turn off the lamp? Some explanation will be appreciated. Thanks.
If you bring a finger or hand near the lamp it locks it on. If you do it a second time it turns it off. It does not have to be touched.
Your design is beautiful and elegant. Almost like jewelry.
Awesome work!!!!. I think this is one of the best and creative stuff I've seen :)
Associated Instructable: https://www.instructables.com/id/DIY-Touch-Sensor/?ALLSTEPS The QT113 is an obsolete chip. A Google search revealed that the chip is part of the Qprox IC manufactured by Atmel. Atmel do not have it listed on their web site. There are equivalents and also an Atmel forum which I did not pursue.
A quick search in the UK shows the QT113 as obsolete but there is a surface mount version available from Farnell. It's made by Atmel so they should have a distributor in your country too. It's Farnell p/n 1608967, the pins are about 1.2 mm apart so it is possible to solder it by hand. Trouble is it's &pound;4.50!! Lovely circuit and application though! I'm inspired!
Thank's very much, I've been looking around the place for a while and wasn't having much luck. I'll have a go with that chip, thanks again :)
Beautiful, simple and really cool! Love the overlapping stripes effect.
yeah the overlapping is a real eye catcher, lol.. caught mine for sure
looks professional, no doubt you could sell thease and people would buy them. incredible thinking, great project!
Can one do this with an Arduino?
I'd recommend coating the soldered board with some clear varnish, so that the copper doesn't tarnish, and it's protected from accidental shorts. Very, very cool design!
Really love it and gonna make one :D

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Bio: I believe that the purpose of life is to learn how to do our best and not give in to the weaker way.
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