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DIY Homemade laser diode driver

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nztdm

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Hello.
I have created a tiny driver module from your circuit diagram but the diode and resistor are not exact, look at the picture.

Will the 1N4004 do in place of the 1N4001 and will the 4.7ohm do instead of the 4ohm?

Also, does the potentiometer have to be any wattage, or is very low current passing through it. My potentiometer is 0.5watt.

 



Things

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Those multiturn pots aren't rated anywhere close to 0.5W, and yes, they need to be high wattage. For driving at 445nm diode, you need at least 1.25W.
 

lasersbee

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Your 1N4001 Rectifier Diode is fine. It can handle 50V PIV.

Your 4.7 Ohm resistor is also fine but will limit the max
current output of your driver a bit lower.

Your Pot should be OK. The higher the wattage the better.
The driver's adjusted output current does flow through the
resistor and the Pot...


Jerry

You can contact us at any time on our Website: J.BAUER Electronics
 
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nztdm

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Thanks for the quick replys people.

The jaycar store catalogue said the multi turn pot was 0.5watt but the are probably wrong since the pot is so small.

Also, if the full laser current is running through the resistor and pot, they are both way too small because I will be running the laser at almost 2watts. I can get a 1W or 5W resistor but I don't know where I could find the pot at such wattages. I live in new Zealand.
 

nztdm

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What values would I use to power an M140 445nm at 1.5A constant current? My power source will be one or two 18650s.
 

ronox

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hello,
i have a concern about this driver, that noone seems t have spoken about.

my laser diode can only take 2.3v, and its important i dont go over, however, here there is nothing about setting the output voltage, just the current.

how do i make sure the voltage isnt too high?
or does it automatically handle voltage? essentially meaning that i could run any LD off the driver required i set the correct current limit?

im just a little worried is all, since theres all this talk of saying you need to use a source voltage 2 or 3 volts higher than your desired output, yet others talk of using up to 30v, which makes no sense as no diode could take 30v
 

HIMNL9

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A current regulation driver auto adjust the voltage for keep the current as presetted ..... if your laser diode is rated for, say, 100mA, and you preset the current driver for keep 100mA through it, regulating the voltage is not needed.
 

Purplemonkey

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I'm trying to make a driver for a 1000-1500 mw infrared diode with the lm317lz regulator. The diode needs 2.0 -2.2v and 1.2-1.6 amps. However I'm struggling to figure out how to regulate the voltage and current as I'm not sure what resistor and pot I need for correct current and how to get 2.2v forward voltage at the same time. Do I need two lm317's? Any help would be appreciated.
 

rhd

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I'm trying to make a driver for a 1000-1500 mw infrared diode with the lm317lz regulator. The diode needs 2.0 -2.2v and 1.2-1.6 amps. However I'm struggling to figure out how to regulate the voltage and current as I'm not sure what resistor and pot I need for correct current and how to get 2.2v forward voltage at the same time. Do I need two lm317's? Any help would be appreciated.

If it was me, I'd grab a 4x AMC7135 driver. For $3, you have a driver that can power an IR off a single cell, versus one (if you use the LM317) that will require two.
 

Purplemonkey

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Thanks, but what I'm confused about with laser diodes is the relationship between forward voltage and amps needed as you can get different drivers that output different voltages but all put out the same constant current. I.e if forward voltage is 2.2 - -2.6 and amps are 1.2-1.6. What will happen if I get a driver circuit with output voltage of 3.3 v and 1.4 amps?
 

Purplemonkey

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It's bugging me how an earth it is even possible to get 1.5 amps at 2v as tried calculations with ohms law and they don't seem to work
 

JollyKillBill

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Is a test load really needed? Like can I just build it and connect it to the LD?

And can I leave the pot out, sounds like its not really needed
 

Things

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No, for a simple linear driver you can just short it through your DMM on the 10A mode for current readings. However I would recommend you test it first - one stupid mistake could pop your diode.

Yes, you can leave the pot out and just use a fixed value resistor.
 

Purplemonkey

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More like this one. Usually you won't want the mode stuff.

If you want 20x of them, you can get them pretty cheap in bulk at DealExtreme.


Can you recommend a host kit to fit this circular driver and to-5 9mm infra red laser. Driver works great By the way. Just trying to figure out how to get more distance out of it. At the moment it only burns at a maximum distance of 9" do I need a special sort of lens to get further distance?
 
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