Old 08-31-2012, 08:32 AM #1
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Exclamation Forward Voltage Drop

Hello, i bought this 2 pack of cheap 20mW blu ray diodes, but i do not know what the forward voltage drop is, in order for me to build my driver as small as i want i kneed to be able to know the forward voltage drop of the diode. They are 55ma @ 2.2v working current/voltage. I don't kneed exact numbers, just rough estimates. Or if you know, then what is the average forward voltage drop of a blu ray diode?

Any help is appreciated

I only have a space of about a 1/4 inch by 1/2 inch round to work with for a driver....
So Here is my stupid driver plan.

https://7cae72e4-a-62cb3a1a-s-sites....attredirects=0



Last edited by Johntabby; 08-31-2012 at 10:35 AM.
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Old 08-31-2012, 09:48 AM #2
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Default Re: Forward Voltage Drop

about 4 to 6V, the highest Vf of the common diodes.
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Old 08-31-2012, 10:19 AM #3
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Talking Re: Forward Voltage Drop

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about 4 to 6V, the highest Vf of the common diodes.
the forward voltage drop a crossed the - & + pins ins that high?
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Old 08-31-2012, 10:23 AM #4
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Default Re: Forward Voltage Drop

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Originally Posted by Johntabby View Post
Hello, i bought this 2 pack of cheap 20mW blu ray diodes, but i do not know what the forward voltage drop is, in order for me to build my driver as small as i want i kneed to be able to know the forward voltage drop of the diode. They are 55ma @ 2.2v working current/voltage. I don't kneed exact numbers, just rough estimates. Or if you know, then what is the average forward voltage drop of a blu ray diode?
That figure isn't right. Vf of the BR diodes are more 5-6V.
The red diodes have a Vf of 2-3V and the 445nm diode 4-5V
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Old 08-31-2012, 10:25 AM #5
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Default Re: Forward Voltage Drop

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That figure isn't right. Vf of the BR diodes are more 5-6V.
The red diodes have a Vf of 2-3V and the 445nm diode 4-5V
Heres the ones i got. It say 2.2v @ 55ma

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Old 08-31-2012, 10:31 AM #6
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Default Re: Forward Voltage Drop

Why do you want to know the Vf ? The current of the diode is much more important as all lasers drivers design for constant current output. As long you set the current to 55mA the voltage of the driver will automatically adapt to the diode.

Read this compilation of the diodes, http://laserpointerforums.com/f51/di...ead-45042.html
Only the current are given for each diode.
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Old 08-31-2012, 10:37 AM #7
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Exclamation Re: Forward Voltage Drop

Quote:
Originally Posted by Blord View Post
Why do you want to know the Vf ? The current of the diode is much more important as all lasers drivers design for constant current output. As long you set the current to 55mA the voltage of the driver will automatically adapt to the diode.

Read this compilation of the diodes, http://laserpointerforums.com/f51/di...ead-45042.html
Only the current are given for each diode.
Here is what i have for a driver idea, i don not have room for a lm317. And i do not know of any tested working pre-made drivers that are this small, my space available for a driver is only 1/4 deep by 1/2 round! And in order to find out my resistor value i kneed to know the diode forward voltage drop.

https://7cae72e4-a-62cb3a1a-s-sites....ts=0:thinking:

Last edited by Johntabby; 08-31-2012 at 10:39 AM.
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