Simple LOC question

[foulmist]

Hi guys...

I was wondering what is the typical and maximum voltage at which a LOC red laser diode can operate!

At my driver right now L1117 and 18650 battery the diode is showing that it uses around 2.3 V ?? is that too low ? I've read that it needs 2.8 ~3V ?

I once tried putting 2 x 18650 in series because I thought that there wasn't enough input voltage and that the excess voltage will be converted into heat by the L1117 but when I tried it ... the diode died ... although it was current regulated!! why did that happen?

Please some of the experts here answer cheers

 

[anselm]

2.8V ~ 3.4V, depending on current, sounds about right to me.
2.3V is pretty low, I'm guessing your driver is starving for voltage, because it's driven
by a single LiIon.
Beware there are several different Long Open Can red LDs.
Not all can take the same amount of current and live.


How is your L1117 set up? Did you wire it as a constant current source, like the
LM317 driver? If so, what resistor did you use to adjust the current?
Should ideally be 3.2Ohm or slightly higher....

 

[foulmist]

Yes i did a L1117 Driver a constant current source at 2.9Ohms .. should be running at 431mA.. i have tested it with a LM317 constant current drive and 7.2 Volts and is running pretty good there... but my L1117 seems to need more voltage I guess but will 2 x 18650 or 2 x 17340 batteries will be too much ?

 

[foulmist]

ok so i made my test load and it measures 2.97v where the laser diode goes
but when the laser is there it measures 2.45 ? maybe my diode uses less voltage ....:yabbmad:

 

[anselm]

So that was with ONE LiIon? And also what current did you get?
What does the test load read when you use TWO?

What diode is it anyway? An LPC-815?

I think a single LiIon might not be enough voltage to drive a red diode even with a L1117.

 

[foulmist]

ok here is all the info i could get :

Red laser diode taken from LG DVD Burner 22x speed Long Open Can
With 1 x 18650 Test

Test Load Voltage - 3V at full charge
Laser Diode Voltage - 2.45 steady

With 2 x 18650 Test:

Test Load Voltage 3.45 at full charge
Laser Diode Voltage - NOT TESTED (don't wanna burn it)

with 2 x batteries the driver gets pretty hot!!!!
so i guess one battery is enough !!!

i can't measure the current!!! I don't know why ... my test load consists of 1Ohm x 1WATT Resistor and 4 x 1N4007 diodes but when I meausre mV across the resistor it shows 0.00 ???

when I put the laser diode it burns stuff but I can't measure the exact current withdrawn!!!

can someone explain to me why my test load doesn't show the current fed into the circuit?!:cryyy:

edit:

my driver consists of L1117 chip 2.9Ohm resistor across ADJ and OUT and 2 caps input and output (10uF and 47uF) + rectifier diode for reverse polarity protection across the laser diode positive and ground pin