DIY Homemade laser diode driver

[toked323]

another i tied 3 10 ohms to make 3.8 ohms and 2 10 ohms to make 5.4 ohms

 

[toked323]

when you look at the picture negativ begins at 1N4001 diode

 

[millionaire]

About how long does it take digi key to get stuff to canada?

 

[ericab]

toked323;


;D

nuff said.

-eric

 

[Daedal]

toked323, I like it. It looks small enough and it's good enough for any setup

I hope you enjoy it... With this no one can kill any LD's from accidental 'surges'

--DDL

 

[Daedal]

About how long does it take digi key to get stuff to canada?

To Canada, I couldn't tell you. But to me in the US it takes a few days usually. Do not recall it taking more than a week ever.

I love DigiKey... even their packaging is amazing!

--DDL

 

[toked323]

if i put 10 ohms instead of 5 ohms will that make more Ma's or will it burn out the diode? also anyone know were i can get a sexy looking case it doesnt have to be a flashlight or anything just small and simple

 

[Daedal]

10ohm will give you 125mA current supply. Now that all depends on what you want to drive your LD at

--DDL

 

[toked323]

i want to drive it at least 180mw

 

[Daedal]

At least? I'm assuming 180mA, not watts... :-?

To get the amount of current you want out use the following equation:

Iout = 1.25/R

If you need 180mA = 0.18 A, then you need the following:

R = 1.25/0.18 = 6.94 Ohms

7 ohms will do just fine

You might have a hard time finding 7 ohms, so try using something like this...

you'll need 3 4.7 ohm resistors. Put 2 of them in parallel and one in series with the other 2, this gives you 7.05 ohms. That nets you 177mA

GL;
DDL

 

[toked323]

i dont know all that stuff i just need 180mw of laser power from the diode what if i put 3 ohms or 2.2 ohm resistor instead of the 5.4 ohms will that bring me to around 180mw

 

[Daedal]

You want 180mW output?

Does your LD support that high of an output? If you're using the SenKat GB diodes... then I do not suggest going below 5 Ohms. But if you want 180mA of power, then you'll need 7 Ohm resistance.

The SenKat GB diodes are only rated at 80mW CW. We push them higher though, and personally I think 5 Ohm is a very good spot.

--DDL

 

[Gazoo]

At least? I'm assuming 180mA, not watts... :-?

To get the amount of current you want out use the following equation:

Iout = 1.25/R

DDL

Daedal, How does that formula work considering everyone is probably using different voltages. As voltage increases, so does current.

 

[toked323]

o thought they were rated for 250mw senkats GB diodes so they can burn i want to push it higher if u can please tell me how..... oh yea [highlight]20%off techlasers for the first 20 buyers[/highlight]<---this is borderline spamming, man....PM me with why you find it neccessary to promote this company please.... <-----Pm to SenKat, please

****EDIT*****Asked for clarification

 

[Gazoo]

Gazoo --

You mentioned in an earlier post that the RS 25 ohm pot goes down to 0.3 ohms. that low reading is probably the test prod leads. Touch the test prods together and you will likely read between 0.3 and 0.5 ohms.
I point this out here because now that a bunch of you are working with low impedance circuits, you need to account for stray readings.

Mike

Mike,
I have found you are correct. At my cheap meters 200 ohm reading, it gives me a reading of .2 of an ohm when the leads are touched together. On all other settings it zero's out.

My Radio Shack meter has autoranging with zero adjust. The rheostat shows a value of 0 homes when turned all the way
down using this meter. Thanks for pointing this out...

 

[Daedal]

[quote author=Daedal link=1185701612/195#201 date=1189118433]At least? I'm assuming 180mA, not watts... :-?

To get the amount of current you want out use the following equation:

Iout = 1.25/R

DDL

Daedal, How does that formula work considering everyone is probably using different voltages. As voltage increases, so does current. [/quote]


The reference voltage for the LM317 is a steady 1.25V. Adding voltage on the input line is not supposed to change that, if it does, then it's a faulty regulator

--DDL