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FrozenGate by Avery

BluRay Driver?!

The two diodes most likely have different operating specs. I was going to use two different power supplies.
BLU FIRST !!

Mike
 





Likewise - I just went out and bought two NTE1900 regulators in anticipation of my Blu Ray package arriving.  (Like an LM317 but only 100ma in a small package.)
I probably won't be able to resist pushing both buttons at once, at least briefly  :)
 
Dude... Don't.
I've blown two already, being careful. Try that and you'll let the magic smoke out.
 
OK, so maybe someone can help me think this out. I've got a current regulator that is similar to he daedal circuit. LM317-based. It outputs 11-150ish ma, adjustable. The problem is, it runs from 6-9VDC, and doesn't regulate the voltage at all. I'd rather run it off a 9Volt, but get 8.6v out. Too much for the blu-ray diode, no matter how low the current is. I blew my second diode that way. I'm thinking a resistor in parallel with the diode will drop the voltage enough to make it safe. Anyone tried that with their diodes before? I guess I'll have to use ohm's law and based on the current, decide on the value in order to drop it by at least 2.5-3 volts... Any thoughts?
 
If you regulate the current, the voltage takes care of itself, except that the excess is dissipated by the regulator as heat.
So if you use a higher input voltage, your regulator will get warmer, but it will always output the voltage that results in your target current being met (or less).
 
Hmm. So maybe a flip-flop to alternate between the Blu-ray and the red LD, so they're never on simultaneously?
Did you have separate current-regulation for both diodes?
How long did you have both of them on when it died?
 
Zarniwoop said:
Hmm. So maybe a flip-flop to alternate between the Blu-ray and the red LD, so they're never on simultaneously?
Did you have separate current-regulation for both diodes?
How long did you have both of them on when it died?
Click to expand...
That's pretty much what I was daydreaming about. There would still be the problem with having to wavelengths that would each need a different lens position for collimating.
 
Zarniwoop said:
If you regulate the current, the voltage takes care of itself, except that the excess is dissipated by the regulator as heat.
So if you use a higher input voltage, your regulator will get warmer, but it will always output the voltage that results in your target current being met (or less).
Click to expand...

I'm not an EE, but this strikes me as highly unlikely. Mainly because this IS how I blew my second diode. I was being SO careful about the current (and static). I checked to make sure it was the same on the weak battery vs. the new one. X ma each time. But when I measure the voltage, I get a 9.2v 9volt (or 6AA's) battery dropping to 8.6@45ma, vs the 8volt (weak) 9volt battery getting put out at 7.4@45ma. I assume that even that was pushing it.

I think what I'm going to do is stick an 80ohm resistor in parallel with the diode. According to ohms law, at 45ma, it will consume 3.6 volts, giving me 5 volts to the diode.
 
A regulator like an LM317, when you get right down to it, regulates voltage.
In one configuration it can regulate the output voltage directly in comparison to its reference voltage.
In the current configuration like everybody here is using, it regulates the output voltage relative to the current, as measured by the voltage-drop across the resistor (or pot) you put between the Out and Adj terminals.
That will vary the output voltage until the current reaches the level you set.
The device will of course consume more current as the voltage supplied to it goes up.
When the current reaches the setpoint, the regulator will limit the voltage, indirectly limiting the current.

Were those voltage measurements made under load? If so, something's wrong because you should be seeing a voltage very close to 3V across the diode.
 
well it is an lm317-based circuit, but I don't have the one daedal posted. it's the one on the top left: http://www.mi-lasers.com/cgi-bin/shopper.cgi?search=action&keywords=diode_parts
Input Voltage: 6 to 9 VDC, a 9 volt battery works well.
Input Current: 26 to 125mA, depending on output setting.
Output Current: 11 to 109mA, user adjustable.
Regulation: ACC, automatic current control.

To answer your question, no, the voltage i mentioned was not measured under load, just directly to the meter.
So I guess my question is going to be: If the current is what matters and voltage is all but irrelevant, why did the diode blow when I went from around 8 volts to 9.2? The current was the same.
 
You might have not been getting an accurate reading with your meter if it was on the 100 ma scale. These diodes do not allow for much overhead, so if you applied 50 ma's to it this could kill it. If the regulator is regulating properly, then the current and voltage going to the diode would be the same as long as the input voltage is 6-9 volts.

You bring up a good point and have reminded me to use a 1 ohm resistor is series with the diode. Measuring the voltage across it will give you the current reading and I believe it is a lot more accurate as well. In addition measuring current with a meter really isn't the safest way. One must remember to have the meter hooked up before applying power. Otherwise the full voltage the capacitor is charged up to will be discharged into the diode.

I did notice that the driver you are using has test points. Are they used to measure current?
 
Good points Gazoo.  Darned if that doesn't look like a 1.0 Ohm resistor across the test-points on that driver board.  Maybe they are for current measurement.
I killed a diode myself by hooking up a current meter with power applied - wasn't thinking.
Oh, also, when I said I'd expect to see around 3V across the diode, I was thinking about red.  For a Blu-ray, closer to 4.5.  Measuring the output voltage without a load I'd expect to see the input voltage minus the Vdrop of the regulator.
And yeah, running a Blu-ray like these at 45ma leaves no margin for error.
 
Umm, they aren't test points dudes,,,,,,
they are connections from one side of the board to the other... a little hole, coated internally with solder or something conductive, probably the same stuff as the tracks
 
aw fooey, maybe two of them are test points. :P
well, think about it though, not all of them can be test points, after all, how could the board possibly work if they weren't connectors?
 
They are test points.
To tell the truth, I don't know exactly how that works. 1 ohm resistor, you say? I measured 30-odd mv on it, I think, last night. I will try again tonight and see what current it's outputting at the same time. I doubt I'll do much with it though. My diodes should be here this afternoon!
 
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