Touch Sensor & LED backlit mirror -- trouble shooting required

Discussion in 'The Projects Forum' started by Anoop Singh Gill, Jun 16, 2015.

  1. Anoop Singh Gill

    Thread Starter New Member

    Jun 7, 2015
    1
    0
    hi all,
    I set out making a wall mirror for myself which when touched at a specific spot would switch on led backlights fitted behind the mirror.
    I used a 12volt/3A SMPS as the power source, used a LM7805 with the required capacitors to get 5 volts, fed the 5volts to a capacitive touch sensor I bought off amazon which uses ttp2336 the link is copied below
    http://www.amazon.in/TTP223B-Digital-Sensor-capacitive-switch/dp/B00NHLNTR0
    shorted two pins on the ic so that the sensor toggles (switches on when touched once and switches off when you touch it a second time). I use the output of the sensor to power a led strip (bunch of 5630 leds mounted on a mcpcb) that runs on 12volts through (a) Solid state relay (b) transistor (c) mosfet. I tried all three with the same result.
    Now the problem:
    the circuit works just fine meaning that the led strip switches on and off till such time that the led strip is away from the mirror. The moment I place the led strip under the mirror (the led strip does not touch the mirror and is a good 2-3 inches below the mirror) the sensor refuses to switch off. When you place it away from the mirror the sensor starts working just fine.
    I am attaching link to a small video I uploaded to vidme I made showing this crazy phenomenon.
    https://vid.me/9s29
    Any ideas as to what might be causing this - and any solutions would be greatly appreciated
    thanks in advance.
    Anoop
     
  2. ericgibbs

    AAC Fanatic!

    Jan 29, 2010
    2,503
    380
    hi,
    Most mirrors have a metallic silvered back surface, the effective large area of the silvering could cause problems with a capacitive touch switch.
    E
     
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