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Guide QT110 Touch-Sensitive Button Guide

Discussion in 'Modding' started by gongzero, 16 Oct 2005.

  1. talladega

    talladega I'm Squidward

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    im not sure about all those chips stuffs but i would build a circuit so that on the output of the qt110 where it will go to where you want the switch connected along with ground i would have a chip that will only allow one pulse to go through once it has received two pulses within a certain time frame. how to do that i have go no clue but im am sure there are chips you could use to do that.

    what are you gonna use it for BTW?
     
  2. mvagusta

    mvagusta Did a skid that went for two weeks.

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    That's what my proposed circuit idea is supposed to do! I wanna have a touch switch that you tap twice/double-click to turn on the pc. To prevent accidental turn on or turn off basically, and i think double clicking is cool :D
    I think i've got it figured out!

    First i'll need an active high touch switch.

    I'll use a 555 timer, that on the first click of my switch starts counting and makes a single pulse after a set time. I can use vr's so i can tweak the timing of this pulse the way i want it - i can set the time delay of the second pulse to suit the speed of the double click - this is where you set the time frame!

    I then have an AND gate, that takes in the output of the 555 circuit and the second click of my switch, so that if the double click is timed correctly, the output of the AND will be high, otherwise the output of the AND will still be low. This AND gate is basically comparing my double click from the touch switch to the preset time frame from the 555 timer circuit.

    The output of the AND goes to a little transistor switch circuit, which remains open circuit on low from the AND, and shorts the output to ground when it recieves a high from the AND.

    I need cpemma & cinnader to give me their opinions on this circuit! Maybe there's a better way of doing all this? Guys? I'll give you both an e-cookie :D
     
  3. One~Zero

    One~Zero What's a Dremel?

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    I think you guys might be making it a little more "difficult" than it needs to be. If you look in the datasheets for whatever chip you are going to use, they have plenty of notes and designs. Also, many of their IC's have eval kits (fairly cheap, depending on where you get them) which could easily be incorporated into your designs.
     
  4. cpemma

    cpemma Ecky thump

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    I've a clap-switch that does what you want, needs two quick claps to work so a random noise doesn't set it off. I'll dig the details out tomorrow, I think it's 2 x 555 timers.

    http://www.rapidonline.com/producti...ects&tier4=Clap+switch+project&moduleno=73214

    No circuit diagram, just a description in the pdf instructions. First clap starts a monostable and arms the device, if there's a second clap before the monostable times out the 4017 counter advances and works the relay. Looks identical to this one and not hard to adapt to a pulsed touch-switch input signal.

    There's another (more expensive) clap-switch kit by Velleman that uses a pre-programmed PIC (but still 2 claps to work); Maplin sell it.
     
    Last edited: 18 Jan 2008
  5. mvagusta

    mvagusta Did a skid that went for two weeks.

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    Thanks for that cpemma :D
    But what do you think of my idea? Maybe i haven't explained it all properly and maybe i should do a circuit diagram but i think mine will use less components so it's a little simpler. What do you think?

    Edit: one "bug" but i can't see it being a problem, is that if you "triple-click" a second low ouput will go to the mobo. I dunno if that would shutdown the pc, it might i think... but i don't think i'd ever do a triple...

    edit 2: big bug found - it won't work at all :waah:
     
    Last edited: 19 Jan 2008
  6. mvagusta

    mvagusta Did a skid that went for two weeks.

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    Ok, scrap my idea, i had the basic operation of the 555 mixed up :hehe: I'm gonna use your suggestion (who would have thought? :D )
    So on to the next stupid question: Which of these is active low output, and which is active high output :confused: I don't mind if i have to use smd.
    I'm thinking to use the active high qt113 output as the clapper's input, instead of the mic input on the clap kit. Would this 5v be too high? Maybe i need a bigger resistor?
    I'm also thinking to remove the relay circuit and the led from the clapper - i'm not sure if the bc548 will have to be setup/biased differently to provide a short to ground for turning on the mobo?

    I've cut'n'pasted a couple of circuit diagrams to illustrate what i mean:
    [​IMG]

    And yet more dumb questions, if i use a larger ohm vr for r7 or r9, would that give me a bit of tweakability for setting the required double click speed? Or is the 10k r10 vr all i need for adjust the required double click time?
    I don't think i need the bc549 preamp! I think i can just send the qt113's high/5v output straight into the first 555 This would remove a few more components aswell which is good.
    Have i done it correctly in the pic?

    One problem i think is that the bc548 output of the clapper isn't momentary is it? I want it to be momentary...

    (lots of e-cookies are in the mail btw)
     
    Last edited: 19 Jan 2008
  7. Ending Credits

    Ending Credits Bunned

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    Is there any chance of the OP to update those pictures?
     
  8. mvagusta

    mvagusta Did a skid that went for two weeks.

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    Ok, i did some reading, and i see how stupid some of my questions were :duh:
    I think the 555 wants a low input so i'll need to use the active low version of the QT113, which solves a couple of issues and it seems to be all i can get from farnell anyway?
    I think the bc548 output will work for shorting to ground/triggering the mobo - i need this because the 555 has a high output.
    I think i've solved double click speed settings & temporary output time setting as shown in the pic :D
    [​IMG]

    Thoughts?

    I'm still not 100% on which of these are active high or low - it seems that they may all be active low as none have a H as in QT113H
     
  9. muther trucker

    muther trucker I've got a Dremel?

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    Right, after reading extensivly through this thread and suffering a few headaches along the way;
    I've devided I need help producing a touch button.

    Now, this touch button will be used to eject / close the Disc Trays on my DVD Drives.

    Hopefully it works out that i can just "touch" an area on my case and the Disk Tray ejects. (the sensor would be behind 3-5mm acrylic).

    After searching for the parts (or trying too) I found some are no longer available.

    So what I'm asking here is if you could help me find the parts needed, and help with the construction of the overall sensor.

    I know that might be a bit much, but I struggle at the electronic stuff like this.

    Many Thanks.
     
  10. mvagusta

    mvagusta Did a skid that went for two weeks.

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    Try to find the QT113 - lots of electronics shops have it. All you need to do is follow this:
    [​IMG]

    The electrode can be any piece of metal, such as a washer, or offcutt from a pc case. The larger the metal, the higher the sensitivity, and the larger the area will be that is touch sensitive - go too big and it will be way too sensitive- it will trigger if you go anywhere near it!

    The capacitor is the ONLY component you need to buy with this chip! I suggest buying a few capacitors, such as 10nf, 22nf & 33nf. The sensitivity will get a little higher with a bigger capacitor, so you can experiment with each - if you put caps in parrallel, they add up so all these 3 together in parrallel = 65nf. It's possible that you may want more sensitivity than this, if so buy another little cap and add it in parrallel or maybe one 100nf cap to replace the whole lot - whatever! You'll figure out what you want :D
    EDIT: IT'S ALSO GOOD TO GET THE LITTLE .1UF CAP ASWELL TO REDUCE NOISE ON THE CHIP - 2 CAPS IS STILL GOOD :D THIS .1uf CAP HAS TO BE SOLDERED REAL CLOSE AS SHOWN IN THE PIC, LIKE <3MM!!

    You can see how 5v connects to pins 1, 3 & 4.
    Pin 2 is the low output/ground output - which can be used to trigger your mobo, or eject button or whatever.
    Pin 5 has no connection.
    The capacitor goes from pin 6 -7, with the PIN 7 SIDE of the cap going to the electrode - important!
    Pin 8 is ground/earth/0v/PC case - make sure it is a nice low resistance as possible earth connection.

    The only thing that may give you trouble is the eject button wiring - hopefully your eject button just connects a signal to earth - as in one contact of the button goes to earth, and the other goes to other circuitry on your dvd - THIS is the side of your eject button that needs to go to the low output of the QT113. If you connect the earth output of the QT113 to the dvd's earth, nothing will happen :D
    Good luck :thumb: I hope i get some help with my circuit soon :waah:
     
    Last edited: 26 Jan 2008
  11. Ending Credits

    Ending Credits Bunned

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    Try the circuit and see if it works. :p

    Thanks a lot for showing how to work the QT113 BTW.
     
  12. talladega

    talladega I'm Squidward

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    Your fancy circuit may be too complicated for others?

    Is there any difference between the QT110 and QT113?

    so just the chip and capacitor are needed? what about the resistors and IC socket stuff?

    you helped me understand ghe chip better too. thanks.

    one more question. where do you get the 5v from. ive read from the PSU but also from other sources too.

    tanx man!
     
  13. mvagusta

    mvagusta Did a skid that went for two weeks.

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    The QT113 is supposed to be a touch more sensitive so it's better at picking up a touch through a panel.
    It is a good idea to use an ic socket, so you can solder everything in place without heating the ic :thumb:
    Nothing else is needed - some people want to use features of the QT113 like being able to drive a buzzer, leds, etc and that's when other components are involved. There are even weirdos around that wanna make double-click circuits :D
    You can get the 5v from the +5VSB line of your psu. +5VSB should always be providing 5v aslong as the psu is plugged into the wall with the wall switch on, and if the psu has a switch, it also has to be on - So if the pc is off, it still gives 5v. +5VSB is supposed to be the purple wire according to ATX spec, some psu's might use a different color. +5VSB should be pin 9 of your mobo conector. +5VSB usually has a lowish current limit like ~2.5 amps but that is waayyy more than this circuit needs :D
     
  14. talladega

    talladega I'm Squidward

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    what if i run a bunch of circuits (6 or more) off that 5v line.

    for these buttons i with etch it and backlight it with led. how do you work that in so its always on?

    and how do i know what IC socket to buy?

    and what do i solder everything to to make the circuits?

    :)
     
  15. mvagusta

    mvagusta Did a skid that went for two weeks.

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    Do you mean 6 touch switch circuits? If so then no problem cos each touch switch won't use much, similar to one led. If each touch switch is gonna have an led then still no problem cos thats like ~400 ma or .4a at the most.

    A small 8 pin ic socket suits the QT113 - any 8 pin socket will be the correct size.

    You can solder everything to the socket, then plug the chip in. It will take longer to buy a veroboard and alter the tracks to suit, but it will be a bit easier to solder to.

    If you want each of the 6 leds always on, just wire each led with a resistor each, to the +5VSB input. What resistor you will need on each led depends on what type of led you get. You can find that out here If you don't know how bright you want to run the resistors, then you can buy a variable resistor and turn it until you get the brightness you want - don't go too high or you will burn the led! Have a multimeter in series so you can keep an eye on the current - going past 40-50ma is asking for a short lifespan for most leds. If you are gonna mount them behind a panel or button then you should mock it all up to know for sure :D

    Another option is to have each of the 6 leds constant on but all dim - and if any of them are triggered, that led goes high :D

    My circuit is near perfect i think - the last one i posted here is version 3, i'm up to version 6 now :hehe: (crazy laugh)
    There is ONE thing wrong with the simple QT113 circuit - it should have a .1uf cap from pin 1 to earth to reduce noise on the input - it should be soldered as close as possible to the input pin, like right on it, less than 3mm lead is best - ill put up a new one to illustrate this.
     
  16. talladega

    talladega I'm Squidward

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    thanks. ill have to order stuff soon. :)
     
  17. muther trucker

    muther trucker I've got a Dremel?

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    Thanks for your help with the diagram!

    Now I've actually started to locate the part I need, I have a friend who wants a few aswell. (No problem).

    But he's decided he wants one to turn his PC on/off.

    I know this will have to be connected to the +5V rail on the PSU (purple cable I think?) - But surely that's not all there is too it?

    Any Idea's?

    Thanks.
     
  18. mvagusta

    mvagusta Did a skid that went for two weeks.

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    Yep! check a few posts up :rolleyes:
    i've gone over using the purple +5VSB and in my next post i go over some led wiring options & limitations of the +5VSB :read:
     
  19. muther trucker

    muther trucker I've got a Dremel?

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    So you have done :) Thanks.

    I guess I don't refresh my pages that often, I should really turn my PC off and not leave it on standby.

    Sorry about that! :)

    EDIT: How do you effectivly wire anythingto the purple +5VSB from the power supply? - I don't want to break anything :worried:
     
    Last edited: 28 Jan 2008
  20. talladega

    talladega I'm Squidward

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    scissors and glue? lol

    i think just use a pin remover and add in your wire??
     
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