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pocket pal broke

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The_Muffin_Man

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hey

So i just built a jayrob pocket pal laser...it was working great for a couple of days but the rest of the body of the flashlight wouldnt screw into the head...well it would but a lot of the threads were showing so i took it apart to file down the reflector... so i disconnected the wires from the driver going to the laser diode to get the plastic piece off...so i took the plastic piece out and filed it down and resoldered the wires to the driver...put it all back together and then i turned it on and my diode was burnt out...

Any ideas why this happened? and i have another diode (same brand)sitting around can i just hook it up? or is the driver damaged?

Thanks
 





pseudolobster

pseudolobster

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How are you sure it's the diode that's broken?

I'd test everything out first... Check the simple things, like make sure the driver is actually getting voltage, then test the driver with a dummy load to make sure it's not broken.. Check the polarity on everything, maybe you soldered something in backwards. Check that your batteries aren't dead.
 
Hemlock_Mike

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SO, if all you did was mechanical work, the diode should not have burned out unless you hit it with static. SO, I'd look over the connections including case to driver and case to LD. As said above, use your DMM to look for continuity problems.
LD's typically don't burn out all the way SO, I'd look too for a faint light output (LED) from the module with the power on. Don't look into it !!! It might come on :-(. At a short distance, if you see a faint red and if you have current, THEN the LD is dead.

Mike
 
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The_Muffin_Man

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yep it has the LED effect....i have tested the batteries: not dead...checked the connections..still good......i think its burnt out lol.... :'( so ill be ordering another and ill try it again...how do i know if my driver is damaged? I made a little circuit with 4 1N4001 diodes and 1 10 ohm resistor...i know it says to use a 1 ohm one but radioshack didnt have any.....so will that work?

thanks
 
Hemlock_Mike

Hemlock_Mike

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Looks like a dead LD if it's an LED :( What current is it drawing ?????
Often a dead LD still makes a good dummy load.... It still draws current but dosen't lase. I sometines use an old CREE emitter diode as a load too.

Mike
 
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The_Muffin_Man

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well i built the circuit...here it is ...umm which is + driver / - driver / + DMM(or diode) / - DMM....And did i build it correctly? How do I know if my driver is busted?

Thanks
 

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Hemlock_Mike

Hemlock_Mike

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I think you have those diodes in parallel.  You need them in series SO their 0.7 volt junction drop adds up to ~3 volts including a good sized LED to act as a visual ON indicator.
With your present damaged LD, how much current is being drawn off the batteries with the electronics as-is and the LD outputting as a LED?  The regulator may still be OK.

I'm not familier with all the drivers here but if the power got turned on with the LD disconnected, it may have charged a capacitor to MAX and POW when you reconnected it. I try to add a small bleeder resistor to my circuits to limit this problem. That resistor only needs to draw ~0.1 mA to be effective.

Mike
 
pseudolobster

pseudolobster

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Here, you want to change it to look like this:

Hook up the black wire to the negative side of the driver, the green wire to the positive side, add power and then measure across the resistor with your multimeter set to DC voltage.
 

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The_Muffin_Man

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erm..lol i dont follow...i understand the part where you talk about the series and parallel thing...but not so much how i measure how much current is being drawn off the batteries...do you mean put my dmm probes on the + and - from the driver and see how much current im getting? or do you mean measure the batteries to see how much current im getting..? lol sorry only built 2 lasers...(this is the second..lol so i guess its only 1 cause it broke)

Thanks :D
 
sk8er4514

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you can test the driver using a dead diode as well if you can't figure out ur homemade test load. it shouldn't be that hard to put the silicon diodes in series.


i'm saying this b/c I just drew a little picture in MSpaint for a customer of mine and thought I'd share my artwork :)
 

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phoenix3200

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Really? All of my blown diodes are either stuck on or off.

You measure current indirectly by finding the voltage drop across a known small-valued (1 ohm) resistor that is in series with the diodes. Using Ohm's law, I=V/R, which is trivial (1 mA=1 V) for a one ohm resistor.

You are best off not using the current setting on the DMM.
 
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CoZZm0_AU

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I measure current going INTO the circuit (i.e before the driver) rather than at the diode, esp when connected to a boost driver. I read in another thread that having the meter connected after a boost driver can cause issues because it doesn't correctly sense the diode load or something?
 
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The_Muffin_Man

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Hemlock Mike said:
I'm not familier with all the drivers here but if the power got turned on with the LD disconnected, it may have charged a capacitor to MAX and POW when you reconnected it.  I try to add a small bleeder resistor to my circuits to limit this problem.  That resistor only needs to draw ~0.1 mA to be effective.

Mike
Click to expand...

I am using a flexdrive...and i was wondering about how to install the bleeder resistor...also i was wondering if the capacitor still has a charge in it and if it does how i can empty the charge...(like on a rkcstr driver you touch the LD and GD pads...so do i touch the positive and negative pads going to the diode to discharge the capacitor or what...)

Thanks
 
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The_Muffin_Man

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Thats all? Just touch the positive and negative pads that go to the diode? and then just hook my diode up? Is my driver still good? I ordered my diode so it should be here by friday...or monday lol...Ill tell you guys if it works

Thanks
 
pseudolobster

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When desoldering diodes I always try to make sure I touch both pins at once using my soldering iron.. This shorts it out.

I'm not very familiar with flexdrives (I just got my first two in the mail today!), but I'd be surprised to find out they don't have something in place for discharging the capacitors between soldering diodes... If you really wanted to add one, you'd install it across the output pins, shorting out the last capacitor.. Though, I'd PM drlava first before trying this.

You can test if your driver is still good by wiring together a few regular diodes (1n400x) in series, hooking those up in place of your laser diode, then using your multimeter to test for voltage and current
 
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