i would like to run my M-140 diode without any active cooling or TEC
what is the magic point where it can run for hours without damage?
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i would like to run my M-140 diode without any active cooling or TEC
what is the magic point where it can run for hours without damage?
I suppose it all depends on the size and material of your diode mount
what do you intend to use?
... I'm using them with a big passive cooler and currents from 500 - 800mA without remarkable heating for laser-cutting ... It's mostly CW ON for some ten seconds, then OFF for some milliseconds (moving to next line start) with job-times of some ten minutes.
Testing with 1Amp for some minutes was OK too.
I'm running much stronger IR-diodes with highest of 80-90% of the max. ratings (max. 4.5Amps instead of 5A, or max. 8A for 9A) with only passive cooling ... not hitting the max. ratings and thus avoid (over-) heating can increase the lifetime to nearly infinite ;-)
Here the link to a wiki-page I've set up for laser-cutting hints: http://reprap.org/wiki/Laser_Cutter
Viktor
http://images.villageorigin.com/0064.../001.jpg?s=300 Dimensions: 16 x 50mm
its a big black one, with no need of pressing a diode in, which i like because i allready replaced one diode...
i have a glass aixiz lens made for 405-445nm with AR coating
and no driver (will try making one myself, trying to figure out now what to supply the diode)
it will be put in a laser scanner (cheap one with steppers) it does have one fan, but its at the far end of the box...
edit: i also have a 30mW green box (identical) and i dont want <1W as it would overpower the green one
I use my M140 diodes in Aixiz cylindrical mounts, clamped in Pat's mounts (not a whole load of contact area between barrel and mount), which is screwed to a baseplate.
No other cooling applied.
I run these at 1000mW output power in projectors that are 'on' all night (8+ hours) with no problems, and have done for 18 months +
casio run 24 diodes in a small ally heat sink with no tec cooling
... but with only 500mA or 0.5Watts each, so not really overpowered ;-)Quote:
Originally Posted by andy_con
Viktor
so i could probably run 500mA with ease as my casing is pretty big + a tiny bit of air going thrugh
now @ how much Volts?
... I'm driving all my diodes with LM317 or LM338 as current-regulators and max. 12 Volts - the effective voltage will follow the current adjusted by the LM's.
The current ranges for the different diodes go from 200mA for 405nm-bluray-diodes to 8Amps with the 25Watt-IR-diodes ...
Viktor
i use small heat sinks and forced air. i drive them pretty hard. remember, they're under modulation in a projector, so the duty cycle is low.
Attachment 35759
check out LT1083 too, it is a robust IC, low noise, low ripple, 7.5 ampsQuote:
Originally Posted by VDX
... I'm using until 5 of the LM317 (fix set up to 1A each continuous) or LM338 (up to 2A) in a driver with 5 jumpers, switches or relays - so it's possible to set the max. current in coarse steps from 0.5A to 9A and fine-tune it by PWM of the source with a MOSFET to any value from 0 to max set without problems.
With a single LT1083 (I've tested this too) it's more complicated, as here I have to adjust the sense resistor for the max. current ... and with the single TO-220 housing it has a much smaller heat dissipation capability than 5 of the LM's ;-)
Viktor
excellent! thanks :)
that would be an interesting setup
... in post #3 I've linked to a wiki-page I've set up for some laser-cutter infos ... here the mentioned driver in detail: http://reprap.org/wiki/File:9Amp-driver.jpg
Using is as easy as shown in the schematics in the wiki, the sense-resistor defines the current per LM ( I[A] = 1,25[V] / Rs[Ohm] ), the 0R22 resistors (smaller for higher currents) 'harmonize' the single LM's, so the summed currents will be averaged without oszillating, and PWM-driving the diode is done by switching the power to the network through a MOSFET (single TO-220 on the left side)
Viktor
so what driver can i make?
i am not an expert in soldering, but my friend helps me with that
they put diodes in spec'd at 1watt and run them at half power? that seems a strange thing to do?Quote:
Originally Posted by VDX
... I think, it's a matter of heat-dissipating (sizes/prices of coolers) and enhanced lifetimes with 'underpowering' the laserdiodes ...
@mrfloppy - look at the specs of a LM317, decide, which current/power is enough and select the sense-resistor for this ... e.g. a driver for roughly 0.5Watts and 570mA is made with a single LM317 and a resistor with 2.2 Ohms (common used 2Watts or 5Watts-types) ... and an appropriate cooler for the LM ...
Viktor
They're not underpowered per se, but they're pulsed in the projector. Much less heat output. They need to be pulsed because a DLP projector produces different colours by rapidly changing between colours, then rapidly moving the mirror array, turning on the mirrors needed for that colour.