Old 03-02-2008, 04:35 AM #1
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Default Dimly lit laser???

OK, I have a wierd problem, or I've neglected to read something crucial. I've built my driver circuit, and it tests out perfect, however, it does not seem to want to actually drive a laser to a high enough voltage to actually burn anything. I've tried on two diodes, and two different driver boards. in each case with the same results. it started out fairly bright, but still not very hot, the light just got sligtly warm. Then after a bit, it gets dim, and remains that way. It still responds when I turn the pot, but it just doesn't get too bright.

I feel like I'm missing something.

Can anyone give me a clue here?

What to check, what to change? what to test?

Thanks.

Rich


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Old 03-02-2008, 08:45 AM #2
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Default Re: Dimly lit laser???

grab a multimeter in current measuring mode and see how much current is going to your LD.
it sounds like either your batteries are going flat or not enough voltage, or you are overdriving the diodes and killing them.
what battery are you using, how many volts. it should be at least 6-7V for a lm317 driver
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Old 03-02-2008, 12:56 PM #3
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Default Re: Dimly lit laser???

The diode shouldn't get hot, you have to use a heatsink to make sure it doesn't get hot, it can die from overheating aswell.The light isn't suppose to get hot eighter, you won't feel it on your skin unless you focus it into a very small spot.
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Old 03-02-2008, 01:02 PM #4
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Default Re: Dimly lit laser???

Fraid it sounds like you drove your diodes extremely high and blew them. What current were you using??
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Old 03-02-2008, 08:43 PM #5
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Default Re: Dimly lit laser???

Ok, I was using a 9v battery. I think that I was over driving them and fried them. I have two more coming in the mail. I'll try them, how do I ensure that I don't over drive them in the future? when it was bright, I pointed it at my finger and saw little sparks on the tip of my finger, which was cool, but I thought it would actually burn things. Nothing big, but stuff like a sheet of paper, cardboard, pop a baloon, light a match, etch some plastic, styrofoam etc.

Anyway, thanks guys.

Rich
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Old 03-02-2008, 09:00 PM #6
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Default Re: Dimly lit laser???

Quote:
Ok, I was using a 9v battery
Using 9v with the LM317 circuit is not a problem if the set output ma's are within the range of the LD.
You are connecting your LD to a circuit with a capacitor on it via a terminal block......It is very important to short out the capacitor before connecting another LD or the same thing may happen.

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