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20amp 2.0v driver for 808nm diode bar - help !!

R

rkovvur

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I just bought a 808nm laser diode bar from Coherent. Looks like this diode bar has a lasing threshold of 9amps and max of 20amps.

I have been searching the net for a DIY driver circuit to test this diode out, but am unable to find it.

I think i can quickly rig up a test circuit with a 3.7v Li-Po battery and a 0.16ohm/20watt resistor to get about 11amps.

But i am looking for a circuit where i can vary the current (current regulator).

One common one i have been coming across is the op-amp/mosfet based current mirror, but I am still trying to learn its circuit theory.

if anyone has a high current regulator circuit than they can share, that would be great!!
 





For example you can use an LM317 or LM1117 with a 2N3055, and you get somethning about 15A with this configuration.
 
15A though a 2n3055??? maybe 3 or 4 of them IF you want to keep the heatsink smaller than africa, and at less than 1000oC !
 
Don't try that single battery, I'm pretty sure 20A is too much. But 9A threshold? typical 20W diode bars only have a 5A threshold.
I'm planning to use a MOSFET for mine, makes the rest of the electroncis easier.
 
Yes you can get a 60 amp mosfet for a few bucks and then build a driver ckt for it ;)
 
Yeah, 2N3055's = easy circuit

MOSFETS are more efficient but remember transistors are current controlled, while FET's are voltage controlled, so keep an eye on the DRAIN voltage

EDIT

Something like this would work i think, replacing the motor with a load of your choice of course :)
MOSFET-motor-driver.png
 
Last edited:
I didn't say anything about no heatsink needed, and no, a heatsink like africa is not needed lol. Anyway the heatsink will not be small.
 
Rafa said:
I didn't say anything about no heatsink needed, and no, a heatsink like africa is not needed lol. Anyway the heatsink will not be small.
Click to expand...

I know you didnt say no heatsink is needed, but if you pull 15A through a 2N3055 , it will glow red...trust me ive built a load of them, i normally use 3 for every 10A, that gives them a reasonable life, and means you dont have to use 100W emitter decoupling resistors haha.
 
ped said:
Yeah, 2N3055's = easy circuit

MOSFETS are more efficient but remember transistors are current controlled, while FET's are voltage controlled, so keep an eye on the DRAIN voltage

EDIT

Something like this would work i think, replacing the motor with a load of your choice of course :)
MOSFET-motor-driver.png
Click to expand...


I'm unfamiliar with fet drivers...
What do you use for PORT-C2?
 
Easily done but the last post was about 10 months ago. Please check the date on posts else you'll be accused of necroposting. If you have a query about a dated thread, it may be best to PM the person rather than bring back a dead thread.

M
:)
 
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