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Guide QT110 Touch-Sensitive Button Guide

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

  1. One~Zero

    One~Zero What's a Dremel?

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    It sounds like you are just asking for a momentary switch....??? I believe the QT110 offers the ability to select either latching or momentary action, not positive though.
     
  2. coorz

    coorz Miffed

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    Yes it can do both toggle and pulse. See the PDF how to use the OPT1/2 pins for that.
     
  3. paranoidphoton

    paranoidphoton What's a Dremel?

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    Momentary behaviour

    It appears that the momentary switch behaviour that I need is called "DC MODE OUTPUT" and it is described in section 2.2.1 and table 2-1 of the datasheet. There is a limitation, however. It will reset after 60 seconds. Lame. Thanks for your responses guys.
     
  4. H2O-G33K

    H2O-G33K What's a Dremel?

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    Would it be possible to use this in a battery operated environment? I was thinking it could be cool to make an LED frisbee that changes colour when you catch it :)
     
  5. mattthegamer463

    mattthegamer463 What's a Dremel?

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    I doubt it, since it requires 5 volts.

    For a frisbee, it would be easy to make 2 metal rings on the outside, so that when you catch it you complete a circuit that turns on different LEDs. That would be simpler. Plus you would need several of these buttons for it to work, which would kill batteries pretty fast.
     
  6. Denied

    Denied What's a Dremel?

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    To quote from the pdf datasheet associated with the qt110

     
  7. One~Zero

    One~Zero What's a Dremel?

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    Most of the eval kits that they have available use batteries as well :D
     
  8. Denied

    Denied What's a Dremel?

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    I have an issue. Seems I have the circuit built, it detects my touches correctly now (after a fight with a breadboard). But no matter what I'm doing it won't signal the motherboard.

    When I plug the connect the circuit to the header, the machine will power on for about 2 seconds before powering off again. Then when I actually touch the switch, i get a beep but no powering on of the machine.

    Also it will only beep when i actually TOUCH the bare electrode, if I put anything in between it doesn't sound.

    Anyone got any ideas what the heck I'm doing wrong?
     
    Last edited: 4 Jul 2006
  9. One~Zero

    One~Zero What's a Dremel?

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    It sounds like you either have tha IC with the wrong output. One outputs a low while the other outputs a high...I can't remember which is which, but it's in the datasheet. Also, make sure you don't have it setup for a momentary switch, as if you are using it to power your machine, then you will need it to latch. I'm assuming you are using it to power the PC, which means you will need it to apply a ground to the PC power supply's green wire, correct?
    The other issue you mentioned is due to the sensitivity of the switch, which is also configurable with the options input of the switch (I think I recall there is a high or low sensitivity option) and also changing the value of the sensing capacitor. I apologize for the "vague" info, but I don't have the data sheet readily available at the moment, but I'm sure some other users (like Coorz, I know for sure) can give a more clear insight to your problems.
     
  10. coorz

    coorz Miffed

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    Kinda hard to remember almost 2 years ago but i do believe i made the powerswitch in DC OUT mode. Also i powered the circuit from the +5vSB on a WOL header.
    And i used the active high version of the QT110.
     
  11. Denied

    Denied What's a Dremel?

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    I just checked through numerous part numbers and read through the datasheet (to the best of my unknowledgeable electronic ability) but everything points to me having the correct IC. Is there an easy way to check which one is which? (cos this does sound like the most plausible possibility!)

    Also I was under the impression that the power switch to modern ATX computers is simply a monetary switch too? Hence why you can chop and change your reset and power buttons (should the need arise)

    As for the power of the computer, at the moment I am just trying to test to make sure this works to my satisfaction (not going that well so far as you can see). But I currently have the circuit plumbed into the PSU by taking the 5V off the purple line of the PSU and then grounded out on one of the black wires (common ground i believe).

    I currently have the chip set to high sensitivity (pin 5 open) but this could be that I don't actually have much of an electrode other than the end of the actual wire which is only about 2mm in diameter.

    If there is anything else I can stick up here to help assist the troubleshooting please tell me, as I say, I'm an electronics n00b of the utmost degree... I can solder but actually UNDERSTANDING this jive is very touch and go.
     
  12. One~Zero

    One~Zero What's a Dremel?

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    That's incorrect. Power supply switches are not momentary, they are latching. The reset switch is momentary.

    I think the purple with suffice (I think that's a standby power, which is always hot), but you should have the Green wire tied to the output of your IC..I didn't see you mention if you had that connected or not. You want your IC to apply a low to the Green wire when you touch it, this will turn on your supply. When you touch the sensor again, it should shut your PC supply down.

    Yeah, that might be a little too small. You should have something at least maybe the size of your fingertip (doesn't have to be solid, it can be a wire made into a circle or something similar)
     
  13. steveo_mcg

    steveo_mcg What's a Dremel?

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    I can assure you if you are talking about an atx power switch, to go on the front of a pc, then you do indeed need a momentary. The latching type hasn't been used since the old AT style! I've rebuilt lots of these and usualy use maplins vandal resistant momentary (non locking) style switch.

    edit:
    If you were to bulid a switch into the atx block then you would want a latching one but you would only do that if you were using it for an external power supply for a test board or a water pump etc not for powering you pc
     
  14. Denied

    Denied What's a Dremel?

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    Ummm... Power switches for AT cases may be latching. But power switches on an ATX computer are most definitely momentary.

    The purple is definitely +5V and always hot. That's not an issue.

    At the moment I am really thinking that it's the active high IC instead of the active low IC. This would explain why the machine turns on when i first connect the circuit and then turns off after two seconds. This is in keeping with normal ATX power buttons, hold the power button in for 2 seconds and the machine shuts down.

    I'm getting out the multimeter in a while to give it a test. And then we shall see if I bought the wrong IC.

    I will also take your advice on the electrode and will just wind a finger tip sized electrode outta some wire.
     
  15. Denied

    Denied What's a Dremel?

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    It was completely my fault... stupid = me

    I had left out the LED + Resistor on the output line, therefore it was always grounding out and not providing the 5V needed to the motherboard.

    So! I have fixed that problem.

    My next problem is sensitivity. I definitely have the gain pin open and it will still only ever detect a push if I physically touch the bare wire. Now, as much as this isn't really the proper behaviour I can modify my mod to incorporate this, but would prefer if it actually works through the perspex. The electrode I'm using is a wound piece of wire about 15mm in diameter.

    Because I was getting sooo many false reads when I built it on the bread board I am using a length of coax as my electrode with the shield grounded out and 20mm of cable exposed before it then attaches to the electrode.

    Anyone got any thoughts?

    Cheers.
     
  16. One~Zero

    One~Zero What's a Dremel?

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    My mistake on the PS....I was baseing it off of mine (which is ATX), but I do use it externaly, as Steveo_mcg suggested.
    There is also an option on the IC where as you "hold" the sensors state for as long as you have your finger on the sensor (essentialy acting like you are holding in the power button).
    I have the evaluation kit for this IC which is pretty nice and might be something you could try. It would save you the hassle of developing it yourself, and I believe they were only about $20 US or so (can't remember exactly) I'll see what's on mine when I get home for options and sensing, but I believe they have a circuit for the eval kit in a PDF on their website.
    Again...sorry about the confusion over the Power Supply :blush:
     
  17. Denied

    Denied What's a Dremel?

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    no worries man!

    I will have two of the QT110's in the mod i am doing. One of which will be used as a latching switch, the other will be used as a momentary.

    There is a limit on how long you can hold your finger on the electrode and cause a signal to be generated. This is specified by the option pins. If you have both pins 3 & 4 tied to the 5V line then you will get a maximum signal time of 10 seconds, if you ground out the 4th pin then you will get a maximum signal time of 60 seconds. After this point it will reset to it's original position.

    As I say, i definitely have the gain pin (pin 5) set to open at the moment, which according to the datasheet is "HIGH" sensitivity. At the moment, unless i can easily sort out this sensitivity problem, i will simply have a small metal bump on my control panel and this will act as my button. Not initially what I was planning but it gives me the functionality that I am chasing.

    So! If anyone knows what I'm doing wrong... please o please tell me! :)
     
  18. Fladlish

    Fladlish What's a Dremel?

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    I've actually got the same problem.

    I'm going to get a new cap that is 22nF and try it, it might make the whole thing more sensitive. One can allways get a qt113 which you can add a cap with a higher value or a cap that is variable..
     
  19. boardsportsrule

    boardsportsrule What's a Dremel?

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    I am wanting to do this, but i cannot locate a qt-110-dg(dual inline package) for sale in the US of A...sooo, i am wondering if i could use the qt-113-dg and treat it the same. it says it doesnt support the peizo sound thing, which i didnt want to use in the first place, so it seems like it would work assuming i left out the whole sound part. any one see a problem with this, or any other differences bettween the qt110, and the qt113?? thanks :)
     
  20. Fladlish

    Fladlish What's a Dremel?

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    Actually the qt113 is a better choise then the qt110. This is beacuse it has a better sensibility. The qt110 has some problems with materials thicker then 1-2 mm. The qt113 has a variable gain hence you can cntrol it's sensibility by changing some caps. Well you can see for your self in the datasheet over at Qprox's webpage, they got a great forum there aswell.
    The qt113 draws a bit more power so if you are going to use a battery it will drain it quicker then the qt110. I

    'm actually getting some qt113 instead of my qt110 because I can't get them to work through 4mm of acrylic.

    Farnell has the qt110 and will ship to the states, could be quite expensive though. But digikey and a qt113 will be better.

    Peace
     
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