Building customs drivers

Hey Guys

I decided to build my own driver. Its capable of basically any voltage input and variable output. I designed it so i can vary the power output with a pot, Its capable of running a few amps with no sweat i was just wondering why not many people build their own. I havent seen many people designing and building their own drivers was just wondering if im missing something???

Thanks guys

Any voltage input? Did you made a buck-boost driver? Can we see?

Many people do make their own drivers, linear ones any ways. Boost and buck drivers are above most peoples understanding with the inductors and IC's so many prefer to buy them pre-made.

Also, drivers are fairly cheap. Benboosts are ~12$ Moh linear's are ~12$ and the X-Drives are 15$, there's not much motivation to make your own when they can be obtained for so little.

Thats a good point lol, i just thought i would make one. Theoretically you just need to maintain a steady voltage to the diode. i have a 5 v regulator with a voltage divider bias, using a variable resistor for the negative side of the divider and another resistor to ensure its never short to ground. Just a couple of capacitors for filtering and that should do it.

Ryan Coward said:

you just need to maintain a steady voltage to the diode.

Click to expand...

I hope you meant current, laser diodes are current driven devices. Driving them with voltage will work, but it's relying on the resistance of your driver to not blow it up.

How do the drivers provide impedence, if anyone could give me a detailed explanation of the driver circuit i will have a go at building one.

Cheers

The Vf of a laser diode is generally ignored when building the driver, the only consideration you need to have for it is the voltage drop (Or boost) for your driver to make sure you have enough voltage, say if you're using a single 18650 (3.7-4.2V).

Many people use the simple LM317 in a current regulating configuration for driving laser diodes. The disadvantage to the LM317 is you need to figure in it's voltage drop, and it's also fairly inefficient, requiring high power resistors and heatsinking.

People use a combination of boost drivers if the laser is to be run off something such as a single LiIon cell, or buck if you're using say 2 or more cells, where you don't need to step up the voltage to meet the laser diodes Vf.

For example, the common A140 diodes are happy running at about 1.2A, Set up a LM317 for 1.2A, and feed it a voltage about 1.5-2V higher than the diodes Vf (4.5Vish for 445 generally) and the diode will be fine running on the regulated current, even if you crank your input of the LM317 right up to 32V (Or whatever it's rated at, provided you have a decent heatsink).

Thats interesting, thanks. Iv used the LM317 regulator and calculated the resitors to creat a 4.2v output to the diode. Im going to test it tomorow so ill let you know if it goes up in smoke lol.

Ryan Coward said:

Hey Guys

I decided to build my own driver. Its capable of basically any voltage input and variable output. I designed it so i can vary the power output with a pot, Its capable of running a few amps with no sweat i was just wondering why not many people build their own. I havent seen many people designing and building their own drivers was just wondering if im missing something???

Thanks guys

Click to expand...

Ryan Coward said:

Thats a good point lol, i just thought i would make one. Theoretically you just need to maintain a steady voltage to the diode. i have a 5 v regulator with a voltage divider bias, using a variable resistor for the negative side of the divider and another resistor to ensure its never short to ground. Just a couple of capacitors for filtering and that should do it.

Click to expand...

You might want to get yourself up to speed about CURRENT regulated
drivers on this Thread if you are using a Linear LM317 regulator...

http://laserpointerforums.com/f42/diy-homemade-laser-diode-driver-26339.html

The LM317 can only accept input voltages of up to 40V in/out differential
and a max heatsinked output current of 2.2 Amps and typically 1.5Amps.

You can read the Data Sheet here....

LM317T datasheet pdf datenblatt - Fairchild Semiconductor - Adjustable Voltage Regulator (Positive) ::: ALLDATASHEET :::


Jerry

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

In my defense any input voltage within reson of voltage supplied by a battery pack, 40v is much higher than one would expect to have in a hand held laser.

Ryan Coward said:

In my defense any input voltage within reson of voltage supplied by a battery pack, 40v is much higher than one would expect to have in a hand held laser.

Click to expand...

We can only go by what you post... You made no mention of
a Hand-Held Laser...:yh:


Jerry

Ryan Coward said:

In my defense any input voltage within reson of voltage supplied by a battery pack.

Click to expand...

More like between 8 and 12 volts. Any lower and it won't regulate properly. Any higher and the heat dissipation will shut it down.

I'd be interested in seeing photos, schematics of your experiments,
but, how about using this sub forum:-
Drivers, Test-load, Power Supply, & Batteries