Need help: Colour sensor triggering oscillator circuit

Discussion in 'The Projects Forum' started by GabeChan, Oct 11, 2016.

  1. GabeChan

    Thread Starter New Member

    Oct 11, 2016
    Hi there,

    first off, I am new to all of this. I am trying to build a little device that converts light of different colours into music. The idea is to have a light shine on a colour sensor that's placed in a dark tube and the light being interrupted rhythmically by rotors with translucent 'blades' in various colours. The light sensor should be connected to a circuit and depending on the colour that hits the sensor, should trigger one or more of an array of little 'oscillator circuits' (not quite, see below).

    I can post a picture of the device in case my explanation didn't help.

    Either way, the device isn't the problem. My problem ist that I have not found a way to make the colour sensor work. I have no history in electronics so my knowledge goes as far as the descriptions in the Nicholas Collins book 'Hardware Hacking' <Link to copyright protected book removed by moderator>i f you are not familiar with it).

    I would like to trigger a circuit with the Hex Schmitt trigger chip 74C14 (as he describes in chapter 18) with this colour sensor diode:
    not precisely a matter of choice, frankly because it is the only one I can buy here.

    my question is thus, is it at all possible, and how?

    I have tried to read the spec sheet good as I can, but honestly I have no clue what I am doing. :sorry:

    The way I put it together for myself is like this (see image), but it doesn't work, I thought maybe the diode doesn't output enough voltage to power the chip? Do I need a transistor? Do I need to wire it differently? Can I run a 9V battery through the colour sensor at all? Does it not react to light from a flashlight shone through a colour filter?

    Any nudge in the right direction is much appreciated.

    Many thanks!
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    Last edited by a moderator: Oct 12, 2016
  2. DickCappels


    Aug 21, 2008
  3. GabeChan

    Thread Starter New Member

    Oct 11, 2016
  4. AnalogKid

    AAC Fanatic!

    Aug 1, 2013
    Your schematic does not show what the three chips are. If they are 74C14's, then the circuit has little chance of working. A photodiode is a strange beast, and cannot drive a logic gate directly without some help, let alone drive its power input pin. If you are trying to use each diode to gate on and off an oscillator, change to a CD4093. This is a schmitt trigger NAND gate, so the same R-C oscillator will work and each diode connects to the other gate input pin with a biasing resistor.

    If the moderators will allow it, redraw the schematic from the book and post the sketch. Without a clear indication of what your circuit is, we're stuck.

  5. hp1729

    Well-Known Member

    Nov 23, 2015
    Taking it one step at a time ... color sensitive sensors.
    A colored LED can be used as a sensor for that color. Shining light on a diode generates a small voltage. The plastic lens acts as a filter. So the sensor might consist of a bunch of LEDs of different colors. Expose it to light and note the voltage pattern you get. microcontroller with an analog input and an analog multiplexer.
  6. GabeChan

    Thread Starter New Member

    Oct 11, 2016
    Hi guys, thanks for the replies, will get back soon. Best,