Setting Current Problems?

[Spyderz20x6]

Hey,
I built a BR laser for my friend a while ago from the PHR diode. This was still when we though 100mA was max for these diodes. So now, he wants me to crank it up to 150mA, because he wants more power. So, my question is: How do i set the current when the diode as already been soldered to the driver?

 

[Bionic-Badger]

If you can find a resistor in the current path, try measuring voltage on that. Otherwise, just turn the knob and hope for the best.

 

[Ryo]

You need a test load (if there's no reistor in the path).

I was told 4 diodes and a resistor in series and using a multimeter, measure the voltage across the resistor.

Current = Voltage/Resistor value

 

[Spyderz20x6]

You need a test load (if there's no reistor in the path).

I was told 4 diodes and a resistor in series and using a multimeter, measure the voltage across the resistor.

Current = Voltage/Resistor value

Didn't i just say that the LASER diode was already soldered on to the driver?

 

[Spyderz20x6]

If you can find a resistor in the current path, try measuring voltage on that.  Otherwise, just turn the knob and hope for the best.

What if there is a resistor on the actual driver?

 

[sk8er4514]

then measure the voltage over the resistor and use ohm's law to calculate how much current is going to the diode.

and you can desolder off the diode if you want to use a real test load.

if you have a laser power meter, you could slowly increase current and measure it until you're happy with the output, and you could use DrLava's 405nm diode roundup picture (link in my PHR803T diode sales page) to figure out about what current it's at if you're really that curious.

good luck,
Kendall

 

[Spyderz20x6]

then measure the voltage over the resistor and use ohm's law to calculate how much current is going to the diode.

and you can desolder off the diode if you want to use a real test load.

if you have a laser power meter, you could slowly increase current and measure it until you're happy with the output, and you could use DrLava's 405nm diode roundup picture (link in my PHR803T diode sales page) to figure out about what current it's at if you're really that curious.

good luck,
Kendall

So i would divide the voltage reading by the resistance value? Also, what is the point of having 4 diodes for red, and 6 didoes for BR as a test load, if the current is always going to be the same?

 

[Hemlock_Mike]

What driver are you using?
How did you measure the current at 100 mA?
How did you adjust it to 100 mA and verify it?

Re-connect your meter to the circuit like the first time and adjust the current control resistor until you read 150 mA.  It's really that simple. After 750 posts, This should be simple -- basic electronics.

Mike

 

[Spyderz20x6]

What driver are you using?
How did you measure the current at 100 mA?
How did you adjust it to 100 mA and verify it?

Re-connect your meter to the circuit like the first time and adjust the current control resistor until you read 150 mA.  It's really that simple.  After 750 posts, This should be simple -- basic electronics.

Mike

1. Flexdrive
2. DMM
2. DMM

I know how to adjust current. My question is: HOW DO I SET IT TO 150mA WHEN THE [highlight]LD[/highlight] IS CONNECTED WITHOUT DESOLDERING IT.

NO I AM NOT YELLING.

I already have my answer though. Find a resistor on the driver, measure the voltage across it, then divide it by the resistance value. I knew the last steps. What i didn't know is that you can measure current with just a resistor on the driver, and no test load.

 

[rog8811]

I already have my answer though. Find a resistor on the driver, measure the voltage across it,

You may find it as easy to put a 1 ohm in the battery path, you know that the indicated mv is equal to 100ma out, do the maths and turn up until you get to your required number..... It will be near if not exact.

Regards rog8811

 

[GooeyGus]

measure mV accross the green r10 (I think thats the value on it anyway...) resistor. It's the green resistor that is on the diode side of the board, but opposite from the pot. That will give you your mA value.

 

[Spyderz20x6]

measure mV accross the green r10 (I think thats the value on it anyway...) resistor. It's the green resistor that is on the diode side of the board, but opposite from the pot. That will give you your mA value.

Ah! Thanks GG!

 

[Bionic-Badger]

Remember next time to list the specific driver, otherwise you'll receive generic answers. I think even Dr. Lava's Flexdrive manual talks of that 0.1ohm resistor on the side you can use to check its current.

 

[Spyderz20x6]

Remember next time to list the specific driver, otherwise you'll receive generic answers.  I think even Dr. Lava's Flexdrive manual talks of that 0.1ohm resistor on the side you can use to check its current.

I don't have the manual, when i threw away the packaging, the manual was still in it.

Edit: Yes, it does tell you about the resistor :-[
I found the manual online...