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FrozenGate by Avery

DIY Homemade laser diode driver

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xgpu said:
I'm new at all of this, I haven't taken electronics since high school so I'm extremely out of practice. If I throw a 47uf capacitor right before the LD will that be good enough to extend it's life? how critical is it to limit current/amperage? I mean, if I have excellent cooling, will the current not be so lethal?
Click to expand...

The capacitor will act like a surge suppressor and help prevent voltage spikes from reaching the diode. You will still need a resistor in series with the circuit to help limit current. Building Daedal's circuit with the LM317T is very easy and will provide the best protection for the price, and current will be constant and not change as long as the voltage supply is at least 6 volts.
 





Skram0... :D :D THAT LOOKS WONDERFUL! It's something to be proud of man. Don't worry about the LM getting hot, warm or boiling... it'll be fine. :P It's made to work like that, and if need be, it lowers the current on its own as it has thermal protection internally. ;)

--DDL
 
HEY DAEDAL CAN I USE A 47UF 50V CERAMIC DISC CAPACITOR sorry about caps i forgot i had them on
 
hehe

Ya, you can... I think that would make for a nice capacitor actually ;)

--DDL
 
thanks and also do you know were i can get a smaller but like still the same power lm317 the radioshack one is too big
 
I think in terms of the smaller LM, go with cutting the top off the TO-220.

As about the pot, that looks like a nice little pot that would work nicely :)

--DDL
 
toked323 said:
oh and can i use this pot?

6MM DIAMETER
SIDE ADJUST
CERMET DUST PROOF TYPE: 31G12 part # 31G12 100 ohms $0.75
http://www.oselectronics.com/ose_p75.htm
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That is a nice little pot but remember it is a single turn so when you turn it just a little bit the difference will be dramatic...but it will work if you are very careful. I don't know what you intend to use it with but the O1B12 pot is a multiturn pot and would allow for more precise control since it is a 15 turn pot.

The 3299W-101 looks like another nice option.
 
I have the circuit working with the GB diode, but even when I max out the pot, I'm only putting 212 mA through the resistor. I have two 10 ohm resistors in parallel there (so 5 ohm total). How low can I go with that resistor to put a little more power though the diode? Along those same lines, what is the highest safe current to put through that diode? I was able to focus the beam and burn a small hole through some black paper, but it took a while. Plus, I couldn't see the beam at all, so I think this diode can give me more.
 
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