how long can you REALLY keep it on for?

mikeeey · Sep 25, 2008

it's normal to assume a 1 minute dutty cycle sounds about right, but I hear blu ray's don't really heat up.. you can leave them on for much longer for a minute and it wont even get hot.
How long can you safely keep a blu ray on for?

flogged · Sep 25, 2008

Depends on the power level you run the diode @, as well as the size of your heat sink.

The diode+heat sink combination will eventually reach thermal equilibrium. You probably want to keep this temperature < 50C.. Ideally <40C (body temperature).

I'm running an 803t diode at 100mA, and with the Meredith heat sink I can leave it on indefinitely, no duty cycle. The casing gets about body temperature warm. I've left it on over 10 hours straight:
http://www.laserpointerforums.com/forums/YaBB.pl?num=1209940381/348

At the upper end of the power range (> 150mA) the diode heats up very quickly and you probably want to keep the duty cycle low. A few minutes on before turning off to cool - and this is with a good heat sink.

andy_con · Sep 25, 2008

my 180mw 405nm in a leadlight case

after 2 mins the end of the pointer is luke warm, so far from hot but also not cold.

on a meter it drops like 2mw after 2mins.

but as it does not have any kind of heat sink i would not want to leave it on for much longer than 2 mins.

also pointers are not meant to be left on for long periods. if you do want to leave a laser on for a long time but a module as thats what they are made for

nvmextc · Sep 25, 2008

I once left a <10mW PS3 on when I went to sleep, and in the morning I though it was dead. Put in a new battery and it was fine ;D

wicked1 · Sep 25, 2008

I had a dream last night that I left my blu ray on overnight... and that the lens was very dirty.. there was speckle all over the place.
so um.. I guess that doesn't help you at all tho, since it was a dream.

I have left my high powered diode on for 5 min or more (180ma). That one did eventually die, but it was at a power up. every one I've had die was at power up.

thesk8nmidget · Sep 25, 2008

i have one set at 150ma and its in a dx heat sink and i can leave it on for hours and it doesnt die.

laserwanabe · Sep 25, 2008

So for example a 803T(100mA) with beefy heat sinc can be on for hours with no damage at all to the diode?

daguin · Sep 25, 2008

laserwanabe said:
So for example a 803T(100mA) with beefy heat sinc can be on for hours with no damage at all to the diode?

While you won't get a guarantee for this because there are too many ways to damage a diode while harvesting and installing, your proposed set-up should be virtually unlimited in its duty cycle.

Peace,
dave

rocketparrotlet · Sep 25, 2008

What about a 120mA diode harvested by ndrew2505, and a jayrob heatsink?

-Mark

laserwanabe · Sep 25, 2008

While you won't get a guarantee for this because there are too many ways to damage a diode while harvesting and installing, your proposed set-up should be virtually unlimited in its duty cycle.

Peace,
dave[/quote]

Thanks Dave

daguin · Sep 25, 2008

rocketparrotlet said:
What about a 120mA diode harvested by ndrew2505, and a jayrob heatsink?

-Mark

This should still be OK. You are approaching the point where the heat sink might not be able to keep up with the diode, but you should still be able to get some very long burns with this set-up. Keep alert and let it cool between burns. Also be aware of the environment. If it is hot where you are, you will need longer cooling periods.

I don't really "worry" too much until I get them up around 150mA. However, keep in mind that I can replace them fairly easily

If you cannot or don't want to replace the diode from time to time, limit your current to below 120mA and use a good heat sink. The 405nm beam WILL still burn stuff at 120mA, it is just a bit tougher to "see" the beam at these currents.

Peace,
dave

laserwanabe · Sep 25, 2008

Its starting to get colder in NY, so i think it would be safe for me to invest in a higher current and keep it heat sinc'd and give it a bit more 'visibility'. So maybe 130-150 would be a safe bet (once i get my brother to give me back my paypal $ which he has forgotten about for over 2 weeks [smiley=undecided.gif])

artix · Sep 26, 2008

How long of a duty cycle would a 150mA PHR with a Kryton groove need?

keeperx · Sep 26, 2008

i have mine in a hunk of aluminum (1"x1"x2") and its set to 140mA. I have left it on for at least 10 min and its fine..

mikeeey · Sep 27, 2008

thanks for the replies everyone! now I have a basic idea.
awesome stories too.

wicked1 I'd have to say yours takes the cake, gave me a good laugh ;D

_________

well I'll be running an 803t at about 115mA in an Aixiz Jayrob heatsink. so basicly at that current it wont heat up? Does that mean dutty cycles arent really required? atleast not the 1 minute on/off dutty cycles.

daguin · Sep 27, 2008

mikeeey said:
well I'll be running an 803t at about 115mA in an Aixiz Jayrob heatsink. so basicly at that current it wont heat up? Does that mean dutty cycles arent really required? atleast not the 1 minute on/off dutty cycles.

Yep. That sounds about right.

Peace,
dave

how long can you REALLY keep it on for?

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