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analog method to blink led when infrared beam is broken

Discussion in 'LEDs and Optoelectronics' started by Beverageexpert, Aug 23, 2011.

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  1. Beverageexpert


    Aug 23, 2011
    Hello I am a noob with analog circuits as I started learning with microcontrollers. I know this would be easy with a microcontroller but would like to have it more simple.

    I have an infrared led and infrared phototransistor that I would mounting in a jar. Anytime somebody puts something in the jar I would like it to blink the led. I thought a pnp transistor would do the trick but it is not working. When I shine the infrared led on the phototransistor the led lights up. I want this to be reversed. Any suggestions?

  2. duke37


    Jan 9, 2011
    Draw your circuit, scan or photo it and post it here. Almost certainly this can be done with a transistor and a couple of resistors.
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