Testload 520nm ?

[jander6442]

After searching and plugging some numbers I just want to make sure here that using the Jufran test load on the microboost driver and setting up for the PL520 diode I came up with the 5th setting range, however when using DMM on the driver output side measuring for voltage I get a little over 6V on the 6th setting.

So what should I shoot for the upper range or the nominal.:thinking:????

 

[sinner]

Upper range is better, the Vf @300mA is close to 7V (6.9V IIRC)

 

[Blord]

I calculate 0.8 V drop for each diode.
Did you add the voltage drop of the 1Ohm resistor ? By example for 300mA that is 0.3V drop.

Btw I use a different testload for the high current diodes like the 5.6mm M140 and the 9mm 445nm diode. It handles the heat better and less voltage drop at the R100 resistor.

 

[jander6442]

Sorry, I thought those diode were more like .9 V drop and the resistor as well. Now I'm really stumped. Maybe Cyparagon or the like could chime in... I'm surprised this hasn't popped up already.

 

[cheech226]

dtr sells the pl520/microboost combo. maybe he'll chime in with how he sets the current.
imo the 6th setting will do just fine. check the output on both settings tho just to see the difference.

 

[jander6442]

Ok so @250mA the PL520 forward V is 6.4V according to the chart google doc @.8 V drop per diode on the testload and .25V (250mA for desired current)

So then:
6.4V-.25=6.15V
6.15 / .8=7.68

so #7 on the testload would be acceptable:thinking:.

 

[Blord]

The Vf of the diodes is dependant on the current. It isn't a fixed value.
If you aiming for 250mA then the Vf is closer to .7Volt.
I would round up and go for 8 diodes.

http://laserpointerforums.com/f39/f...embled-diy-kit-stock-63450-5.html#post1030250

 

[jander6442]

The Vf of the diodes is dependant on the current. It isn't a fixed value.
If you aiming for 250mA then the Vf is closer to .7Volt.
I would round up and go for 8 diodes.

http://laserpointerforums.com/f39/f...embled-diy-kit-stock-63450-5.html#post1030250

That's what I thought. I can't imagine why this hasn't been throw up somewhere I thought I could hold out for awhile longer on the direct green, but NOPE

Thanks Blord rep coming to you.:thanks: Seems I need to get back with you on the rep. system won't let me.

 

[cheech226]

You're going to like this diode jander. i held off for a while but i'm glad i dropped the cash. it has very nice color and good beam too. btw - thanks even tho i was off a bit.

 

[The Lightning Stalker]

The Vf of the diodes is dependant on the current. It isn't a fixed value.
If you aiming for 250mA then the Vf is closer to .7Volt.
I would round up and go for 8 diodes.

I think your calculator is broken.

6.4 - 0.25 = 6.15
6.15 / 0.7 = 8.78571428571

The same result was obtained on KCalc and a TI-86, so the correct setting would be 9.

You are correct about the voltage drop of the 1N5404 diodes on the Jufran board. :beer:
Just as with laser diodes, different rectifier diodes have different voltage drops. Schottky
diodes have a voltage drop of around 200mV. If there was a need for a really accurate
voltage drop, a test load with both types of diodes would work really well. Most drivers are
fairly accurate over a wide range, so such precision is unnecessary.

 

[Blord]

Luckily the Jufran board has 10 diodes. He must have foreseen this coming.