? Volts, milliamps and milliwatts

I must be reading some thing wrong I have a 445nm 1watt diode with the following operating specks (see below please!). I would like to operate this diode as close to its maximum out put as is practical. I have been looking over some of the most popular drivers, (micro boost, flex drive, etc) and none seem to be capable of operating at 1200 ma @ 4.3volts or am I just not understanding the specs of the drivers. I am a bit dense when it comes to electronics. I am how ever aware of the hazards of operating a high powered laser. Proper eye protection will be ordered before the driver.

I know this information must be available here on this forum but I am working a boat load of overtime right now and could use some direction please!

200 ma -- 23 mW* --* 3.7 Vld
300 ma -- 125 mW -- 3.8
400 ma -- 244 mW -- 3.9
500 ma -- 340 mW -- 4.0
600 ma -- 450 mW -- 4.1
700 ma -- 550 mW -- 4.1
800 ma -- 633 mW -- 4.15
900 ma -- 720 mW -- 4.2
1000 ma -- 820 mW - 4.2
1210 ma --1000 mW- 4.3

:yh:canceled my spyder arctic order!

You could use a 2.4 ohm, 5 watt resistor to drop the voltage from 2 x 3.6 volt lithium batteries in series ( 7.2 volts ) to drive the laser diode at 4.3 volts and 1.2 amps.

jd359 said:

You could use a 2.4 ohm, 5 watt resistor to drop the voltage from 2 x 3.6 volt lithium batteries in series ( 7.2 volts ) to drive the laser diode at 4.3 volts and 1.2 amps.

Click to expand...

:scared:

Yikes!! I don't think I'd recommend that approach. I'm using this buck driver with 2 16340 batteries in this host. The performance of this combo has been great, but the diode needs to be well heatsinked (heatsunked :thinking. Mine's in a chunk of copper .

Good luck....

Dave

jd359 said:

You could use a 2.4 ohm, 5 watt resistor to drop the voltage from 2 x 3.6 volt lithium batteries in series ( 7.2 volts ) to drive the laser diode at 4.3 volts and 1.2 amps.

Click to expand...

I'd really, really, avoid ballast resistors to limit laser diode current. Unless you want to kill your diode.

Steve

He could put a large capacitor in parallel with the LD. Simple but not as safe or efficient as a switching LD driver. If the OP is really is not sure of his electronics skills I would recommend getting a kit with the driver's current already preset.

My Flexdrive v5 works with a 445nm diode maxed out @ 1.5A...

pHeneX said:

My Flexdrive v5 works with a 445nm diode maxed out @ 1.5A...

Click to expand...

Interesting! The data sheet seems to imply those current levels are only available for red LDs.

BMWG650GS said:

200 ma -- 23 mW* --* 3.7 Vld
300 ma -- 125 mW -- 3.8
400 ma -- 244 mW -- 3.9
500 ma -- 340 mW -- 4.0
600 ma -- 450 mW -- 4.1
700 ma -- 550 mW -- 4.1
800 ma -- 633 mW -- 4.15
900 ma -- 720 mW -- 4.2
1000 ma -- 820 mW - 4.2
1210 ma --1000 mW- 4.3

Click to expand...

did you actually capture this data or quote it from somewhere?
Either way, the readings after 700mA dont look kosher.
it seems that a connection may have changed during this test before the heating effects started to become evident.
and it wasnt a good idea at all to skip the 1100 mA reading.
if it was me, i'd have run this test at least twice with cool downs between tests.

Be patient if this is your first laser build, especially since this is such a powerful build. Spend the time searching the forum and reading what others have done and you will figure things out. Since your working so much, you may not be able to build it all at once....but then again you don't need to. Make it a learning experience and take your time, it makes seeing those photons all that more pleasing!

Zappo said:

did you actually capture this data or quote it from somewhere?
Either way, the readings after 700mA dont look kosher.
it seems that a connection may have changed during this test before the heating effects started to become evident.
and it wasnt a good idea at all to skip the 1100 mA reading.
if it was me, i'd have run this test at least twice with cool downs between tests.

Click to expand...

What exactly looks bad about it? And why was skipping 1100mA not ok with you?

I just don't understand your objections. Sure, there's some rounding error in the voltage making it look choppy, but it's just from rounding off the numbers. And the L-I looks pretty much straight.

unless there was an error induced through an autoranging change, then it looks like the data points at and above 800 ma are skewed and never recover.
after that linearity starts to droop with what would seem to be the effects of heating beginning right at 1000, but there's insufficient data to see if you really hit the "knee" of the curve.
the missing 1100 data point exascerbates this.
granted, taking data points is tedious, but you only have to do it once.
more data points, perhaps at 50 ma increments, with a soundly connected layout, and possibly even at timed intervals would amplify any reading changes due to heating effects.
once you hit the knee. its a simple matter to back off to what youll be permanently comfortable with and never have to worry again.

Yeah, I'm not seeing anything major wrong with it. It looks quite linear, then starting to roll off towards the end, sure, just like everybody else's charts.

And I'm definitely not seeing the "skew" above 800mA, the L-I looks exactly like I expect it to.

So I'm still not sure what you're referring to. There's some variation, I'm sure, as there always is with measurements, but I don't see anything out of the ordinary. What, maybe 10 mW of "skew"? The L-I is continuous, its slope appears to be continuous as well when you take normal variation into account. There's some slope change as current increases, which is exactly what should happen. :thinking:

This is all good news I thank you all Thanks spartan x for the reminder to remain patient. This is what I think I am going to use. http://laserpointerforums.com/f42/diy-homemade-laser-diode-driver-26339.html check it out every one. thanks again G