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2W 808nm c-mount driver

NaN0T3cH

NaN0T3cH

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Hi, I bought recently a 2W c-mount laser diode and I was wondering how to power
it because there wasn't drivers for this diode on eBay so I decided to do it by myself and I did some research on the forum I know that I need to use a LM350. I just want to know if the transistor will adjust the correct voltage by itself ? And should I put resistors before or after the LM350 ? I want to run the diode at 2 amps with 18650 5Ah battery, will current burn the transistor ? Sorry for my bad English, I hope you have understood what I'm asking. :angel:

Thanks for helping
 





ChaosLord

ChaosLord

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The lm350 can handle up to 3A, so no the current shouldn't hurt it.

If the circuit is built properly, it will feed the diode the voltage It needs along with the current you set it to output.

Look here
 
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NaN0T3cH

NaN0T3cH

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hmm I understand and after some more research I've planned to do like that but my battery is a 5Ah isn't that too much ?
2ym7k9t.jpg
 
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Aleksa

Aleksa

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You seem to not have the basic knowledge,and yet playing with dangerous diodes. I suggest you do a little research instead of burning diodes and others stuff. People here can tell you there experience and a bit of knowledge,but they will not teach you basics.
So,you want to drive your diode at 2.2v 2A. You already drew a schematic which seems to be ok. Your battery is 5Ah,that means that is capable of delivering 5 amps for 1 hour. If you have a load of 2A and a battery of 5A,the battery will still be functioning for 22 minutes. Of course,there is no such thing as a perfect battery,so the discharge curve will be a bit weird. All in all,that battery will suit your needs. Once again,do some research before attempting to play with your diode,or else you might burn it. :)
 
DashApple

DashApple

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Aleksa said:
You seem to not have the basic knowledge,and yet playing with dangerous diodes. I suggest you do a little research instead of burning diodes and others stuff. People here can tell you there experience and a bit of knowledge,but they will not teach you basics.
So,you want to drive your diode at 2.2v 2A. You already drew a schematic which seems to be ok. Your battery is 5Ah,that means that is capable of delivering 5 amps for 1 hour. If you have a load of 2A and a battery of 5A,the battery will still be functioning for 22 minutes. Of course,there is no such thing as a perfect battery,so the discharge curve will be a bit weird. All in all,that battery will suit your needs. Once again,do some research before attempting to play with your diode,or else you might burn it. :)
Click to expand...

If the battery is rated for 5Ah , 5 amps for 1 hour ( 60 minuets ) , then at 2 amps ; that is under 0.5C discharge so that would last over 120 minuets .

22 minuets would be a discharge of just over 10A .


Also the circuit you have drawn if a fixed voltage source , for a laser diode you need a constant current source , for this you use just one LM350 regulator and one resistor , the voltage is taken care of automatically as long as the supply is above all voltage drops combined .

The Vref for the LM350 is 1.25V so for a current of 2A you do -

1.25V/2A = 0.0.625 Ohms , Power dissipated will be 2.5 Watts .
 
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The Lightning Stalker

The Lightning Stalker

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Be very careful with 808nm. What appears as a dim red will actually be very powerful IR. You should
have a decent pair of safety glasses such as the Eagle Pair sold by survival lasers. Always wear them
when focusing and burning.

Here is a link to the DDL driver.

https://sites.google.com/site/dtrlpf/home/flexdrives/rog8811

Leave out the variable resistor and instead go for a fixed resistance, as any potentiometer is going to burn
at these currents. You can find the correct resistance value using the formula R = V / I, where R is
resistance, V is the reference voltage (1.25 in this case), and I is current. I also recommend increasing
the capacitor to at least 100µF ceramic or solid tantalum.
 
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