Would You Believe a 180mW Blu-Ray?

[flogged]

Wow! A factor of two difference in the power level between 7.5 and 12 volts. I would imagine the part with the higher voltage would have a significantly shorter life as tunneling and 'hole migration' would be much worse. .. just a guess tho.

Isn't the optimal voltage on these things determined by the bandgap of the device? If so 5-6 volts is about right.

 

[IgorT]

That's because the current wasn't the same. The only thing it has to do with voltage, is, that the voltage wasn't enough before, for the desired current to flow.

The only possibilities for this are:
- supply voltage being too low
- supply voltage sagging too much under load
- problem with the driver

The end result being changes in the current.

If the driver is regulating, none of this should be happening. If the driver has enough voltage to regulate, the power of the diode will depend ONLY on the current and heat. If the driver has more than enough voltage for regulation, it transforms the extra voltage to heat. That's why linear drivers have a low efficiency - you need to select batteries, so that they have MORE voltage, than the driver needs, when full, and still enough for the driver, when empty. For a red, two Li-Ions are perfect - 8.4V when full, 6V when empty - the current will stay the same all the way down, and the entire battery capacity will be used. For a blu ray, two Li-Ions are not enough. Three have more than enough voltage when full and when empty.

A rkcstr driver needs less voltage on top of what the diode needs than a 317 driver, but at higher currents, the PHR diodes need almost 6V, so even a rkcstr driver can't drive a PHR from two Li-Ions.

 

[daguin]

but at higher currents, the PHR diodes need almost 6V, so even a rkcstr driver can't drive a PHR from two Li-Ions.

There ya go. I didn't know this. That will change the laser "pen's" profile, won't it? No high powered pens without a boost circuit. I think the drlava flexdrive just got more important

I guess my "interchangeable head" lasers, just became "matched sets" of lasers. Good thing I kept the extra barrels!

I also have been setting the current, on the driver, with 7.5V. Then feeding the diode 10.8V in the host! Who knows what my current really is then, eh?


Peace,
dave

 

[Spyderz20x6]

Will a 803T live long set to 150mA?

 

[daguin]

Will a 803T live long set to 150mA?

Define, "long"

They all live the whole time, until they die.

Some trips are longer than other trips.

Peace,
dave

 

[IgorT]

There ya go.  I didn't know this.  That will change the laser "pen's" profile, won't it?  No high powered pens without a boost circuit.  I think the drlava flexdrive just got more important  

Hehe, exactly.. This is why i told you that i'm not going to use a rkcstr driver in your pen, but my own boost driver instead. The higher we push the diodes, the more voltage they require for that current.

And as we kept raising the current for your pen, at a certain point i realized, that a linear driver couldn't cope with it anymore. Even if the diode only required 5V, it would drop out of regulation at just above the batteries nominal voltage (3.6V each, 7.2V together), so less than half the battery capacity would be used.

With a higher current, two fully charged Li-Ions might be able to keep the voltage high enough, just long enough for you to set the current, but when you stopped measuring it, it would drop out of regulation almost immediatelly.

 

[IgorT]

Will a 803T live long set to 150mA?

No one knows man.. That's what we're trying to find out. If you want "long" and "for sure", do not set the current above 125mA (and even this might be risky), and wait for the results of other people's testing.

If you want to contribute to the testing, set it to 170-180mA, and tell us if/when it dies.


I will keep posting updates in the batch testing thread. If a diode dies, it will be mentioned there, together with the currents and the powers each individual diode achieved. At the moment, i am running two at 169.9mA. But with these two, i actually want them to survive.

Still, i never know what will happen, when i press the switch. So far so good.

 

[Spyderz20x6]

[quote author=Spyderz20x6 link=1214100163/72#83 date=1214890076]Will a 803T live long set to 150mA?

Define, "long"

They all live the whole time, until they die.

Some trips are longer than other trips.

Peace,
dave[/quote]
Um.... 4000 hours?

 

[Maelstrom]

Igor, where the heck are you getting so many 803's! IM definately feeling like I will need a back-up or tow...

 

[IgorT]

If you're making lasers, a diode backup is always a good thing to have. Especially, if you're just starting.

You can't buy one diode and be sure the project will succeed. Even with lots of experience, things can go wrong. And even if it does succeed, you still want to have some spares.


Especially with a diode as good as this, when you never know how much longer it will be available.