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DIY Laser Torch - 323mA! - Wow!

Gazoo

Gazoo

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If you are using Daedal's circuit, as long as it is supplied with 6-37 volts, the current and voltage going to the laser diode will not change. It's best to use the formula for the current you want before fiddling.

R=1.25/ma
 





jayrob

jayrob

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Gazoo said:
If you are using Daedal's circuit, as long as it is supplied with 6-37 volts, the current and voltage going to the laser diode will not change. It's best to use the formula for the current you want before fiddling.

R=1.25/ma
Click to expand...
Thanks Gazoo, I can see from this formula which resistor to use for a specific current disired. But , just to clarify...DDL's circuit, no matter running at 250mA or 323mA can be suppllied with more voltage that his original thread stated? Would using more voltage such as two 3.6 batts cause any more heat issues? Such as maybe to the LM317? (I do not know much at all about electronics...but I can follow directions)...
Thanks,
Jay
 
Benm

Benm

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Using a higher input voltage will cause more heat generated in the LM317. If you'd feed it 10 volts for example, at 300 mA it would burn roughly 1.8 watts (0.3 x 6v drop). At that point you must cool the lm317, otherwise it'll go into thermal protection and reduce output current.
 
jayrob

jayrob

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Benm said:
Using a higher input voltage will cause more heat generated in the LM317. If you'd feed it 10 volts for example, at 300 mA it would burn roughly 1.8 watts (0.3 x 6v drop). At that point you must cool the lm317, otherwise it'll go into thermal protection and reduce output current.
Click to expand...
Hi Benm, you seem to be very knowledgeable so please let me ask your opinion about this MXDL change to DDL's circuit, that is, a 3.9 ohm resistor at the LM317. In your opinion, would running two 3.6 volt rechargeables instead of the two 3.0 123s cause any heat issues to the LM317 at this current? Because the current is around 325mA, I am keeping the duty cycle to 1 or 2 minutes anyways.
Thanks,
Jay
 
Gazoo

Gazoo

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I run my labby with an input voltage of 9 volts. I do have a heatsink that clips onto the 317, but it does not get that hot. You shouldn't have any thermal problems running on 2 li-ion batteries with no heat sink.
 
L

LarryQ

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That IS what I am running....

2 RCR-123's at 3.6 V each!

No problems for me at all....and man can this thing BURN!!!!

Larry
 
jayrob

jayrob

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Gazoo said:
I run my labby with an input voltage of 9 volts. I do have a heatsink that clips onto the 317, but it does not get that hot. You shouldn't have any thermal problems running on 2 li-ion batteries with no heat sink.
Click to expand...

That IS what I am running....

2 RCR-123's at 3.6 V each!

No problems for me at all....and man can this thing BURN!!!!

Larry
Click to expand...

Great news! Thanks for that information! I wasn't sure and didn't want to chance it...
Jay

Edit: Just did a test and the voltage is slightly different...2.89 with 3.0 batts and 3.11 with the rechargeables. I guess that 3.11 for the LD is fine huh? Guess so since Larry has been using them...Thanks!
 
jayrob

jayrob

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Finally fried my first Senkat diode last night. This was using the aluminum heat sink in the MXDL and running it hot at 323mA. LarryQ, have you fried any diodes yet at this current? I ordered some more diodes. I think I'll rebuild it using a 4.3 ohm resistor this time...this should put it at around 291mA. We'll see how it lasts at this power...
Jay

Edit: Tested a 4.3 ohm resistor today and it provides 294mA...
 
C

CHP

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jayrob said:
Finally fried my first Senkat diode last night. This was using the aluminum heat sink in the MXDL and running it hot at 323mA. LarryQ, have you fried any diodes yet at this current? I ordered some more diodes. I think I'll rebuild it using a 4.3 ohm resistor this time...this should put it at around 291mA. We'll see how it lasts at this power...
Jay
Click to expand...
Jayrob,

Any guess about how many hours you had on the LD? How long would you keep the LD on; how long would you let it cool down?
 
jayrob

jayrob

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Jayrob,

Any guess about how many hours you had on the LD?  How long would you keep the LD on; how long would you let it cool down?
Click to expand...

I would only have it on for a minute at a time...sometimes 2 at the most and then let it cool for a couple of minutes. As far as how much total time...another guesstimate of only about an hour and a half...not too good. But I have a couple other that have no problems yet! LarryQ says he has been running at this current for some time now. If you read this Larry, please give us your estimates...
Jay
 
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