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Electronics Touch Control Panel Design : New Schematic 05-02-2005 - NEED FEEDBACK

Discussion in 'Modding' started by technomancer, 17 Apr 2005.

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  1. Xiachunyi

    Xiachunyi What's a Dremel?

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    I don't know about the conductive properties of zinc, but for the flip-flop, it will just require one additional chip. Something like Cpemma's setup will work. You could also use the TTL version 74xx74 flip-flop with basically the same principle and hook it up that way.
     
    Xiachunyi, 24 Apr 2005
    #21
  2. mottl3y

    mottl3y What's a Dremel?

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    my guess is that zinc conducts, but why not borrow one and hit it with a multimeter?
     
    mottl3y, 24 Apr 2005
    #22
  3. g0th

    g0th What's a Dremel?

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    Of course Zinc conducts reasonably well, all metals do.
     
    g0th, 24 Apr 2005
    #23
  4. mottl3y

    mottl3y What's a Dremel?

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    i always get it wrong, but i think its aluminium that doesnt. or something...
     
    mottl3y, 24 Apr 2005
    #24
  5. g0th

    g0th What's a Dremel?

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    all metals conduct to a reasonable degree.
     
    g0th, 24 Apr 2005
    #25
  6. Neo4

    Neo4 What's a Dremel?

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    very good idea :rock: :)
     
    Neo4, 25 Apr 2005
    #26
  7. technomancer

    technomancer What's a Dremel?

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    Actually aluminum conducts incredibly well. Most modern powerlines use aluminum cores.
     
    Last edited: 25 Apr 2005
    technomancer, 25 Apr 2005
    #27
  8. technomancer

    technomancer What's a Dremel?

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    Thanks :D Working on the first of two revised schematic using the qt140 chips now. Should hopefully have both schematics up by the weekend.
     
    technomancer, 25 Apr 2005
    #28
  9. cpemma

    cpemma Ecky thump

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    Zinc's a good conductor but not easy to solder to. However, electro-zinc is quite thin, grind a spot back to the steel underneath & solder to that.
     
    cpemma, 25 Apr 2005
    #29
  10. technomancer

    technomancer What's a Dremel?

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    Thanks, that's what I was thinking. I wasn't sure how the solder would adhere (though I'll be using a pocket torch instead of an iron for that part), so that answers both questions. :rock:
     
    technomancer, 25 Apr 2005
    #30
  11. theshadow27

    theshadow27 What's a Dremel?

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    aluminum conducts very well...
    what is bad is when you get AL wire and CU wire and mix them... thats not good and it starts fires
     
    theshadow27, 25 Apr 2005
    #31
  12. technomancer

    technomancer What's a Dremel?

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    QT140 Touch LED Schematic

    Ok, after a lot of work and looking for parts, I've got the schematic for the proximity LEDs using the QT140 finished, so here it is:

    [​IMG]

    Parts list:
    Diagram# : Description : Man. Part # : Digikey Part #
    XT1 : ECS 10MHz Resonator : ZTA-10.00MT : X915-ND
    Cs1-Cs4 : EPCOS 22nF Capacitor : B37981M5223K054 : 495-1067-1-ND
    Cs5 : EPCOS 0.1uF Capacitor : B32922A2104M : 495-1617-ND
    R1 : Panasonic 10K Ohm Carbon Film Resistor : ERD-S2TJ103V : P10KBACT-ND
    R2-R5 : Panasonic 91 Ohm Carbon Film Resistor : ERD-S2TJ910V : P91BACT-ND
    Inv1 : TI IC Hex Invertor : SN7404N : 296-14642-5-ND
    Oi1-Oi4 : Fairchild Optoisolator : 4N25 : 4N25FS-ND

    This would be easier if there was a way to do tables in the forum :D

    R2-R5 are calculated as single LED values. I wasn't sure if that was appropriate or if I should have used parallel values since they can be lit singly or in any combination.

    One of the 'extra' channels in Inv1 will be used for the lighting on/off switch in the other set of controls.

    As always I'm looking for feedback and improvements.
     
    technomancer, 25 Apr 2005
    #32
  13. g0th

    g0th What's a Dremel?

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    Well R2-R5 are each only driving a single LED so that's fine.
     
    g0th, 26 Apr 2005
    #33
  14. theshadow27

    theshadow27 What's a Dremel?

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    guys why dont u just get the dev board for like http://www.qprox.com/products/qt2xx.php
    ?
    wouldent that be easier then rollin ur own out of washers?a


    and in your schematic, you dont need optoisolators... your driving stuff on with a comon ground, you can use transitors...

    also, if you use a PNP transistor you dont need an inverter :thumb: that saves you 5 IC's
     
    theshadow27, 26 Apr 2005
    #34
  15. technomancer

    technomancer What's a Dremel?

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    Not really, since I'd still need to take it apart to get the sensor array and different sensitivity levels I want. :read:

    Nice. So I could drop in something like Fairchild PN3640s. :rock:
     
    technomancer, 26 Apr 2005
    #35
  16. theshadow27

    theshadow27 What's a Dremel?

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    i read the thread lol... IMHO dev boards are alwase the best implementation of their product, so building your own almost never matches up... must just be me :worried:

    here you go:
    [​IMG]
     
    theshadow27, 26 Apr 2005
    #36
  17. technomancer

    technomancer What's a Dremel?

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    Possibly true, but why buy the dev boards when I'd need to desolder and replace components and rip apart the prefab faceplates? Just doesn't make sense. My only real concern in all of this is my (relatively untested) soldering skills, but fortunately I'll be socket mounting the delicate parts (like the QT140) so I'm not likely to fry anything :eeek:

    Oh, the 2N2222s are all NPN btw (at least everything Digikey lists), but I get the point and will revise my schematics in the next few days (finals this week, so it may be a bit). Thanks for the diagram.
     
    technomancer, 26 Apr 2005
    #37
  18. angelorus2000

    angelorus2000 What's a Dremel?

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    the fun is in doing it your self.


    -----------------------------
    my english is so bad :worried:
     
    angelorus2000, 26 Apr 2005
    #38
  19. theshadow27

    theshadow27 What's a Dremel?

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    :duh: :sigh: :wallbash:

    your right. if it was PNP, you would put the load on the other side. my schematic here calls for NPN :worried: i was thinking two diffrent thoughts, cojoined by an EDIT. :waah: its been a long day :D

    da image has been... revised :hip:
     
    theshadow27, 26 Apr 2005
    #39
  20. specialk

    specialk What's a Dremel?

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    Just to clarify, anodized aluminum does not conduct. Plain ol' aluminum does however.

    -special [k]
     
    specialk, 28 Apr 2005
    #40
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