2 Diodes Burned. Help me! What happend?

[Fred_DASP]

I did the DDL an turn the tripot until the diode (from DVD) shine. That´s ok.
The maximum mA meassured was 110mA.

I used turn on and off and take care to not leave the diode get warm.

Today this happend again.
I was using normal, and then suddenly not more shone.

Can I turn the tripod a litle bit more after the shine or only until the shine and nothing more?

Help me! I don´t want fry any more my diodes! It´s so hard to find...

 

[Fred_DASP]

:'(

 

[goldfingerfif]

Where was the diode from? What kind of diode was it?

 

[rog8811]

A few questions....
Is your LD in a housing?
Is your LD soldered onto the circuit or just clipped on with croc clips?
Have you got the capacitor the correct way round?
How did you measure the ma's?
Did you test the circuit fully before connecting the diode (see this thread  http://www.laserpointerforums.com/forums/YaBB.pl?num=1197651171  )

Answer those and we can see what will need to be done.

Regards rog8811

 

[Fred_DASP]

_Is your LD in a housing? - Yes.

_Is your LD soldered onto the circuit or just clipped on with croc clips? Croc Clips in the soldered wires [ Croc here ====D- ]


_Have you got the capacitor the correct way round? I saw 2 little SMD capacitors in the near circuit, so i thought that I could use then.

_How did you measure the ma's? I measure the currente in 2 ways. I put the resistor in series and then measure the mV, and put the amperimeter in serie too. Both give me same result.

_Did you test the circuit fully before connecting the diode? Yes.


Can I turn the tripod a litle bit more after the suddenly shine or only until the shine and nothing more?

What is the temperature max of a LD ?

 

[rog8811]

I saw 2 little SMD capacitors in the near circuit, so i thought that I could use then.

Do you know the values of them? The reason for having one is to absorb spikes from the battery when you turn it on, so it needs to be rated at at around 2 to 3 times battery voltage. The ones you have used could be little pf decoupling caps which will not do the job.

Be sure of your capacitor before you tweak the pot..... If the values are right and you know that the circuit does what it is meant to do then by all means do so, but I suggest you put a 1ohm in positive side of the LD supply and measure the voltage drop across it (remember mv=ma with 1 ohm) to ensure you don't go too high.

Regards rog8811

 

[Fred_DASP]

The capacitor is so important ?
I´ll weld those caps at all my IR an Red Diodes right now!

And about my other question?
"Can I turn the tripod a litle bit more after the suddenly shine or only until the shine and nothing more? "

Tnks by the last answer

 

[rog8811]

I´ll weld those caps at all my IR an Red Diodes right now!

If the capacitors have been used before short out the two leads with a screwdriver to discharge them first or they will kill the LD, if soldered straight onto the LD pins they will do a good protection job no matter what else you do....within reason .

Post the make and model of the DVD you harvested the LD's from, someone here may then be able to give you an idea of the max ma you can safely run at, in other words how much more you can turn the pot after the lase point.

Regards rog8811