Touch Sensors - three models

Discussion in 'Hardware/Parts' started by neilhart, Jan 30, 2015.

  1. neilhart

    neilhart Moderator

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    Jan 30, 2015 at 7:53 PM #1
    neilhart

    neilhart Moderator

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    - Standalone Capacitive Touch Sensors - vender: www.adafruit.com

    I found these sensors some time ago and first used them on my Mini-ITX Tower project. On that project I used the “Standalone Momentary Capacitive Touch Sensor” for the power on switch and the Standalone Toggle Capacitive Touch Sensor for the lamp switch.

    [​IMG]

    Today I am using the “Standalone 5-Pad Capacitive Touch Sensor Breakout - AT42QT1070” and wiring up a control panel with a touch power on, a lamp on and a lamp off and a reset; this will use 4 of the 5 sensor circuits. And because I prefer to not add electronics to motherboards, I am using relays to isolate the touch sensors from the motherboard logic.

    Here is the 5-pad unit on my desk. I have a copper penny as a pad taped to a .187 inch thick ABS plastic plate and my finger is being sensed through the plate as evidenced by the lit LED.

    [​IMG]

    These units are reasonably priced and Adafruit usually ships same or next day. I use US Postal Service and the shipping cost is very reasonable.

    Good modding,
    neil
     
  2. minihack

    minihack

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    Mar 1, 2015 at 2:43 PM #2
    minihack

    minihack

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    Hi Neil,
    I am thinking of trying one of these with a Cube mod and probably using a large area Copper shim as the contact to hopefully maximise sensing ability. I suspect though that the thickness of acrylic at the top of the Cube case might just be asking too much. How thick have you managed to go and still get a sensed touch Neil?
     
  3. neilhart

    neilhart Moderator

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    Mar 25, 2015 at 10:25 PM #3
    neilhart

    neilhart Moderator

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    minihack sorry for the late reply as I had not noticed your post.

    It appears that these units calibrate at power on and seem to sense a touch at a fair distance.

    On my current project, I had cut down the size of the pad to reduce the sensitivity for the reset switch and set the pad back into a hole. But then is ABS and not the cube acrylic.

    Good modding,
    neil
     
  4. ShatteredAvenger

    ShatteredAvenger

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    Apr 3, 2017 at 3:32 PM #4
    ShatteredAvenger

    ShatteredAvenger

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    Sorry to dig up an old thread, but I'm in the process of using the same adafruit sensor in my cube project. I haven't actually soldered or tested anything, but in my mind I'm not sure how this would work. Neil, how did you wire yours? I had thought initially if I just put the output of the PCB to the + terminal on my header that it would work, but the more I think about it, I'm not sure that will actually suffice.
     
  5. neilhart

    neilhart Moderator

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    Apr 14, 2017 at 11:00 AM #5
    neilhart

    neilhart Moderator

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    When I add external electronics to my hack systems I use small 5 volt DC relays for isolation. In the case of Adafruit sensors, I have the sensor pulling up the relay, and the contacts of the relay wired to the motherboard front panel pins for the power switch.

    Good modding,
    neil
     
  6. ShatteredAvenger

    ShatteredAvenger

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    Apr 25, 2017 at 9:03 PM #6
    ShatteredAvenger

    ShatteredAvenger

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    Sorry, blew a PSU and got pretty busy at work for a week or so.

    Neil, what you're saying is that you have the adafruit sensor just sending the signal to another relay- I assume in this case it's the momentary single-pad switch that sends an active high, correct? Has anyone done something similar with the active low send?

    Incidentally, I still have the original sensor as well. Is it possible to add an external pad to that one by any chance?
     
  7. neilhart

    neilhart Moderator

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    Apr 30, 2017 at 5:43 AM #7
    neilhart

    neilhart Moderator

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    Do a bench test of your original sensor and play around with it. I think that minihack has documented some alternate setups;

    I am never comfortable with connecting my electronics to a motherboard directly, such as the power and reset switches as we do not know what the circuit is on each motherboard. So when I use an adafruit sensor, I rig the sensor to pull up a 5 volt relay and use the relay contacts to provide the function of a momentary switch.

    Good modding,
    neil
     
    ShatteredAvenger likes this.

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