LDR to turn on a strobe light

Discussion in 'The Projects Forum' started by bafuller83, Dec 4, 2012.

  1. bafuller83

    Thread Starter New Member

    Dec 4, 2012
    6
    0
    Hello, I want to make a circuit, that when dark, will switch on a mini emergency strobe light. It is the type of strobe that when charged to a certain point, emits a flash. The more power it recieves, the faster the flash. It runs off of two AA batteries.

    I want there to also be a manual on/off switch, so that I can turn it off on the nights that it is not in use.

    Below is a circuit I got online, which I believe powers a LED. Is it possible to replace the LED with the strobe.

    Are there other simple circuits that could do the same thing?

    I am very new to electronics and have tried reading some books on the subject but am having a hard time on my own. So I am looking to you guys as my mentors!

    Thanks a lot, any input is appreciated!
     
    • s1.png
      s1.png
      File size:
      119.6 KB
      Views:
      31
  2. MrChips

    Moderator

    Oct 2, 2009
    12,415
    3,354
    A strobe is a different beast all together requiring 300VDC.
    You would be better off to stay with a high intensity white LED.

    Why do you want the light to flash?
     
  3. wayneh

    Expert

    Sep 9, 2010
    12,088
    3,027
    So your strobe light is self contained, and you just need to power it on and off depending on the light level?
     
  4. bafuller83

    Thread Starter New Member

    Dec 4, 2012
    6
    0
    I want it to be a regular strobe, but activated but darkness. It needs to be able to be seen over a mile away so I want it to be a strobe.
     
  5. MrChips

    Moderator

    Oct 2, 2009
    12,415
    3,354
    I have done this before.
    Take a photo flash unit. There is a storage capacitor of about 300uF at 300v that needs to be charged up for each flash.

    Replace this cap with something smaller, say 47uF at 300v allowing it to charge more rapidly.

    A feedback circuit triggering a diac will cause the flash to self trigger.
    The LDR circuitry can be added for dark trigger.
     
  6. bafuller83

    Thread Starter New Member

    Dec 4, 2012
    6
    0
    Im not sure I understand "self contained", but I'm guessing there is a diode in the light housing that when the load gets big enough dumps it on the light, making it flash, and then repeats.
     
  7. bafuller83

    Thread Starter New Member

    Dec 4, 2012
    6
    0
    Here is a pic of the strobe. The outer circle is the positve the middle is the negitive. If I touch wires to the + and - it will charge and flash. Also is a pic of my work area just for fun, got a ways to go.
     
  8. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    6,357
    718
    I believe he was asking if the strobe was a complete unit, ready to plug in to 12V or 120VAC and would start flashing. If so, use a solid state relay (SSR), opto-triac, or standard relay coil to close the power switch when the light is at the preset level.

    If you want to build the strobe light as part of the circuit, that will get more complicated, as you'll need an oscillator to boost the voltage high enough to trigger a strobe tube.

    For the 1 mile distance, how focused/directional does it need to be, and at what intensity? Aircraft warning light brightness, or "something is over there" brightness?


    --ETA: Saw your picture added, is this for an R/C Aircraft? If so, 3W or 5W LEDs are very good substitutes for strobes, easier to drive, and overall less weight.

    I noticed your strobe is self contained if you only need to add power, the question now is: What voltage does it need at input, and what current does it draw while charging/running?
     
  9. wayneh

    Expert

    Sep 9, 2010
    12,088
    3,027
    Exactly right, and that makes it a much simpler project.
     
  10. bafuller83

    Thread Starter New Member

    Dec 4, 2012
    6
    0
    It is for a high altitude balloon experiment. I plan to use GPS to track it, but though it would be useful to have a strobe that activates at night, just in case I have not found it by nightfall. I also plan to put a loud beep on it, and maybe out things.
     
  11. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    6,357
    718
    What is your power supply, and what voltage/current does your strobe run on?
     
  12. bafuller83

    Thread Starter New Member

    Dec 4, 2012
    6
    0
    It runs off of 2 AA batteries, Im not sure about the current.
     
  13. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    6,357
    718
    Do you have a DMM that can measure current? Knowing the peak current the strobe will be drawing is a rather important aspect when designing a circuit to control it.
     
Loading...