LD Driver help plz

hi

i followed the diagram for the driver on the website www.rog8811.com/laserdiver.htm

and the circuit is working and i measure the mv across the 1 ohm resistor and it measures 26mv which is equal to 26ma ( the current the laser diode will see). it laso measure 2.9 v across the diodes in the test load but i guess it doesn't matter since the circuit will regulate the voltage to the LD.

so i disconnected the circuit, discharged the capacitor and connected the LD ( LD positive and the pin 2,which connected to the case, is negative.

here is the datasheet for the LD

DL-3147-165 pdf, DL-3147-165 description, DL-3147-165 datasheets, DL-3147-165 view ::: ALLDATASHEET :::


but it didnt work, i tried to change the value of the resistor on the potentiometer but nothing happened.

can u suggest what went wrong and how can i check if the LD burned or not ?

Re: LD Driver help

Hey,

Very little info about your particular setup there but as you have had this working at some point then we have to assume you have the driver circuit correct.

There is no real way of checking if you've blown your diode except by trying another diode and seeing if it works. Bit risky if you're not 100% sure you have a safe driving current.

Personally I would have carried on asking these questions in your other thread - http://laserpointerforums.com/f52/plz-help-50417.html - It would be more polite and makes sense to keep continuity so others can learn from your experiences. Jerry was giving you some great learning there.

However, killing diodes is a fact of life here. It's not difficult to harvest yourself another from a DVD drive, (even the reader LDs are likely to out power that 5mW! ), so, once you've checked your circuit, plumb in a new one and away you go.

BTW, is/was your LD in any type of housing or just bare? Even the 5mW ones will overheat without any heatsinking.

M

Re: LD Driver help

Try connecting an LED to the driver, does it light up safely without popping?

Re: LD Driver help

first of all, thanks for replying

ofc i want to share my experience with everybody and laserbee was of gr8 help. the problem is that i posted the other thread in the wrong section, so i thought i would post in the right section to get more answers.

the circuit is on a breadboard so there is no casing. i measured across the 1 ohm resistor 26mv and it increases as i decrease the resistance which means the circuit is a success. i dont know whats wrong. u are right, maybe it is the laser diode but i thought there is a logical explanation for this problem or it happened with someone before.

so if anyone experienced this problem before plz help me

Re: LD Driver help

What's the laser diode? 26ma is pretty low; it might be below the threshold current for your diode.

Re: LD Driver help

harryd said:

first of all, thanks for replying

ofc i want to share my experience with everybody and laserbee was of gr8 help. the problem is that i posted the other thread in the wrong section, so i thought i would post in the right section to get more answers.

the circuit is on a breadboard so there is no casing. i measured across the 1 ohm resistor 26mv and it increases as i decrease the resistance which means the circuit is a success. i dont know whats wrong. u are right, maybe it is the laser diode but i thought there is a logical explanation for this problem or it happened with someone before.

so if anyone experienced this problem before plz help me

Click to expand...

When you tested your Driver what was the Max and Min that you could
adjust your driver using the Test Load...:thinking:

Jerry

Re: LD Driver help

I also think 26mA was not nearly enough. If it was a LOC, then it needs at least, IIRC, 85mA to lase.

Re: LD Driver help

ok i think i figured it out. now when i measure the output current from the circuit without the dummy circuit, it measures 30 BUT NOT MA, micro amp and when i measure the voltage across the 1 ohm resistance using the test load it measure 30mv.

shouldn't 30mv equal to 30ma??


and btw the datasheet is included at the beginning. it says the max operating current is 40 or45 so i cant go over that

Re: LD Driver help

anyone