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
    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
    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.
    Any ideas as to what might be causing this - and any solutions would be greatly appreciated
    thanks in advance.
  2. ericgibbs

    Senior Member

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