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Registered Member #56
Joined: Thu Feb 09 2006, 05:02AM
Location: Southern Califorina, USA
Posts: 2445
hmm, mine had nothing on the die, I just dremeled off the cap and there it was :) I can't say as to if air effects it, but I ran mine (it was a motorola branded one) for a little while at 1amp, and I didn't notice any problems. I can't test it now as I blew up the leads going to the die by hooking it up to 2 seriesed gel cells 8) I would say it had about 3 minutes of run time, consisting of 3x 1 minute runs limited by the case getting too hot from my poor heatsinking (it was clamped in a vice)...
Registered Member #33
Joined: Sat Feb 04 2006, 01:31PM
Location: Norway
Posts: 971
I just tried it with a 2N3055 and a 2N3771. The die of the 2N3771 was about 4 times the size of the 2N3055 die, so i required a bit more current. The 2N3771 sparked over and died at around 15V and 3A, the 3055 died silently, and I didn't watch the meters at the time I am at school now, so I didn't get any pictures.
Registered Member #29
Joined: Fri Feb 03 2006, 09:00AM
Location: Hasselt, Belgium
Posts: 500
I seem to remember someting about carrier recombination in the base region of bipolar transistors as being the source of the light.. I'll have to dig out some of my old semiconductor physics texts...
BTW- In this article, they have utilised a hetrojunction bipolar transistor as a laser!
Registered Member #87
Joined: Thu Feb 09 2006, 01:36PM
Location: San Jose
Posts: 191
Tonight I'll try it with a heat sink and perhaps a tiny lens. Perhaps the smaller the die the more intense it gets, more current through a smaller path of conduction.
Registered Member #27
Joined: Fri Feb 03 2006, 02:20AM
Location: Hyperborea
Posts: 2058
I had a second look and the resin combined with overexposure made my first pictures look like it was glowing. The new picture shows that the light is almost white with a slight green/yellow cast. Using a IR blocking filter made no difference. A visible blocking filter showed almost no picture so nothing is glowing in the traditional sense.
Registered Member #103
Joined: Thu Feb 09 2006, 08:16PM
Location: Derby, UK
Posts: 845
You can also use transistors/LEDs as the 'worlds worst phototransistors'. If I remember correctly, this was how video cameras were made possible - it was discovered that the resistance of a semiconductor changed when they 'closed the door' (according to a certain program).
Registered Member #27
Joined: Fri Feb 03 2006, 02:20AM
Location: Hyperborea
Posts: 2058
This is my best attempt at getting a spectrum. The bars are wide enough to run into each other so it needs some interpretation to decide if it is a continious spectrum or not. Taking the width of the bars into account I don't think it is full spectrum but I would not bet on it.
Registered Member #84
Joined: Thu Feb 09 2006, 01:06PM
Location: Dallas, TX
Posts: 47
I have used EMMI (emission microscope) at work to look for the same thing. It's much more sensitive, though. It's good for finding individual junctions breaking down on a large semiconductor device. Of course, it doesn't need near the power in the junction to see any light emitted!
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Worlds most inefficient LED
