Stan_Ham diode driver (analog)

[Laseradct]

Hi guys.

I have a question i hope someone can help me with. I am all green when it comes to electronics so bare with me.

I just made this driver today, I did it from the original layout and components from page 1 of this thread. I hooked up my 405nm 100mv laser and it doesnt get enough current so its barely visible. Which resistors would I have to change to get a higher output.

Best regards

Nicki

Ps. I also build the DDL driver based on LM317, which works perfectly with my 405nm so I know that the laser module works as it should. However that driver doesnt have modulation so thats why I made this one instead

[LaNeK779]

R16 i suppose... and then adjust accordingly via the two 10k pots (idle and main)

[Laseradct]

I thought R16 only protected the LED?! What is the difference and function of main and idle pots? I figured main is for when it is operational, but im a bit unsure about that. Im running the driver on 12v btw.

[stanwax]

R9 is the one you may need to adjust - its designed to run red diodes which drop 2v, the other thing is to run at a higher supply voltage - but 12V is plenty so no worries there.
drop the val of R9 to 0.5 ohm - placing another 1R across the one already there will be ok.
The pots control the threshold of the driver and the set point (max) but if the either pot is at zero you may not get any drive turning the other pot. In this case start by turning the max pot a few turns - not too much and then with the mod input on 0V turn the thresh. pot til the diode just starts to turn on then back it off again till it just drops out.
Then put 5v on the mod input and increase the current till you get to the right level (using a meter to measure the volts across R9) - remember that the reading will reflect the value change - with 1R the reading on the meter will be converted directly to mA so 200mV will be 200mA but with 0.5R the volts reading will need to be doubled to read the current - so 200mV will be 400mA
Rob

[Laseradct]

Stan! Thank you very much for that thorough reply! I will be testing the changes when i get home tonight

[stanwax]

No Probs and its Rob not Stan (or Loretta)
Rob

[Laseradct]

It worked well, thanks Rob.

I do not recommend running 12v into this driver, DB437(t1) gets litteraly smoking hot almost instantly. I think I will look for a lm317 (or likewise) based ttl/analog driver. Feel free to link one in, if anyone knows of a good one

[stanwax]

If you are stuck with 12v why not pass through a 7808 regulator first - that will loose 4v still provide enough drive for your diode and reduce the power dissipated on t1 by a factor of 4xdiode current.
If the driver suits then this is a simple solution that will cost very little
Rob

[Laseradct]

Yes you are right that would work. Think i will try that. I have tried feeding 5v to the ttl input, but it makes no difference. Still laser is active with no change at all. Do you have an idea what i am missing here?

Thanks again.

[virushunterz]

Hello. i'm Michael . and i what to ask you some important Questions ?
Ok first i build that driver (it's complete). so i plug to the diode connection a L.E.D. and nonthing happen. you know what just please explain me how to connect everything and some specs about the driver:
Modulation speed
mA Range
Voltage ?

Please Help me i really need that Driver