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Circuit Help

  1. May 25, 2005 #1
    Circuit Help!!


    I am trying to design thsi circuit for some friends, however, having the 2 light bulbs in the circuit seem to "eat" all of the power, cuasing the laser to be VERY dim. Isn't there an electronic component taht i can jump across the light bulbs that will allow them to stay lit (no matter how dim) while letting the laser get close to full power? It is a 28 volt DC circuit with a 5 amp circuit breaker in it. The power source has a common ground with the circuit.
    Thanks in advance.

    Attached Files:

  2. jcsd
  3. May 25, 2005 #2
    you are trying to indicate that the laser is on??
  4. May 25, 2005 #3
    Yes, i have it set up so it can be turned on or off from 2 different places, w/ indication that it is on. I would use lower impedence bulbs, but i don't have any. The Laser in infrared, so it can only be seen w/ NVG's.
  5. May 25, 2005 #4
    going to bed now, if anyone can help, please do, thanks
  6. May 25, 2005 #5


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    Why not have your power indicator lamps in parallel with your laser instead of in series?
  7. May 25, 2005 #6
    How would i do that?
  8. May 25, 2005 #7


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    You don't want your load (laser) and indicators to be wired in series; you want them to be wired in parallel. Use one switch on the the 28V supply for the entire circuit. Alternatively, use a relay to switch the laser's supply.

    - Warren
  9. May 25, 2005 #8
    Do it like this. Consider the LED to be the laser. Depending on the ratings of your lamps, you might want to put the lamps in series, maybe even with a resistor (but keep the laser parallel to them).

    Attached Files:

  10. May 25, 2005 #9
    i hope this pic comes out..
    it shows your laser connected to your 28 V power source ..
    you did not say how much current your laser uses ?? just that it had a 5A fuse..therefore i could not specify exactly what R1 should be..but it should be just enough to fully turn on both FETs thus turning on your indicator lamps when the laser is on .. also i did not include the switch but you can put it in the leg comming out of the battery positive..

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  11. May 26, 2005 #10


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    Actually in some comercial lasers (Coherent) there is an Laser emission light that is on when the beam is active. It is a safety feature, the light MUST be on when the beam is on, the way it is wired if the bulb burns out the laser will not come on.
  12. May 27, 2005 #11
    This is such a noob question, but why is willib's diagram grounded? I can see why cosmik's diagram is ground (to complete the circuit), but why does a circuit connected from - to + on the battery need to be grounded?
  13. May 28, 2005 #12


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    It is just to indicate which side of the circuit is attached directly to the negative pole of the battery. It is at the lowest potential of the circuit, zero volts.
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