Simple beep instead of LED light?

Discussion in 'General Electronics Chat' started by Barryp, Feb 23, 2012.

  1. Barryp

    Thread Starter New Member

    Feb 23, 2012
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    I have a camera studio flash that illuminates a "Ready" LED when the flash has reached full power. This is pointless unless I'm starring at the back of the light. Instead, I would like to add a circuit or some type of self contained beeper either in series or parallel with the LED that will beep once.

    The beep should be fairly loud as sometimes I can be 20-30ft from my flash unit.

    I took a high school electronics class and can read basic schematics--more recently built a 4W FM transmitter from plans.

    Any information on how I can achieve this beeper would be greatly appreciated. Thanks in advance to those that reply!
     
  2. #12

    Expert

    Nov 30, 2010
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    Tough one. The LED is very efficient so there isn't much power available to steal from that connection and make sound with it. One option is to move the LED to the side you can see. Another option is to know how the flash unit works and steal some power by modifying it. A third option is to use a completely different power supply, like a wall wart, and have the light from the LED trigger that source of power to run a sound device.
     
  3. gerty

    AAC Fanatic!

    Aug 30, 2007
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    A piezo would the most efficient beeper as it draws very little current. As to connecting it to your flash unit, that's going to be the challange.
     
  4. Barryp

    Thread Starter New Member

    Feb 23, 2012
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    Thanks for the quick replies!

    #12- The problem with moving the LED is that it would be impossible to see from far away in bright sunlight. I haven't opened it all up yet, but I'm sure I could establish a power source--Would if help if I photographed the board?

    Gerty- Would a piezo just beep once? or would I need to run some sort of timer circuit? I'm fairly confident that I could solder it on, or run wires to mount it externally.

    I'll take some photographs and have them up after dinner.
     
  5. #12

    Expert

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    Here are a couple of piezo beepers. They make sound as long as power is available. Now to find some power to run them with by looking inside the flash unit.
     
  6. gerty

    AAC Fanatic!

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    They make piezos with various on/off cycles, all self contained, no driver needed. I'll see what I can locate. #12 is correct, as long as there is power applied they will beep. I think they make one with a slow beep (long time between beeps). Don't know if that will suffice for you.
     
  7. Barryp

    Thread Starter New Member

    Feb 23, 2012
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    I'm starting to think a photo resistor connected to a buzzer would work best so I could easily remove it when I don't need the audible notification--I could just power this with a 9v or AA's.

    Is there a simple schematic for this somewhere?
     
  8. #12

    Expert

    Nov 30, 2010
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    A schematic of a battery powering a photo resistor and a buzzer? It's too simple. Just put them in series.

    The problem here is finding a photo-resistor that goes from about 36K to less than 83 ohms when looking at an LED. Maybe an opto-coupler would work better. They are designed to look at LEDs and have current gain.
     
  9. gerty

    AAC Fanatic!

    Aug 30, 2007
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