1 watt driver

[Benny_Hill]

Hello again, just wondering if there is some hope for this problem. I received a 1000mw 808 diode from ebay, and am stumped on how to do the driver. The multimeter that i have is only good till 400ma then it blows the fuse or kills the meter. I need to make a driver that supplies between 1000ma-1400ma, but dont know how to test it when done. I was hoping there is someone out there with the ability to do the math, as I do not wish to blow this diode, it cost 70$ and took a month to get here. Below are the specs, could someone please help with this one? Im stuck, and dying to wire it up.



WAVELENGTH (nm): 808 -+ 5nm.
THRESHOLD CURRENT (mA): <350
CURRENT MAX (mA): <1400
VOLTAGE NOMINAL (VDC): < 2.2
WAVELENGTH TEMP COEFFICIENT (nm/DEG Cel): 0.3.
EMITTING AREA FACET (MICRONS METRIC): 100X1
3 PIN
SEALED UNIT, HEAT GLASS.

Please help! I am dying to fire this thing up, but dont want to pull a n008 on this one!

Thanx, Benny

 

[MarioMaster]

sounds like you need a new meter then - but an LM317 can do up to 1500ma with proper heatsinking so that should work fine

 

[supernova]

You may want to use a LM338 and re-design your circuit as the LM338 can handle more current.

SN

 

[Benny_Hill]

sounds like you need a new meter then - but an LM317 can do up to 1500ma with proper heatsinking so that should work fine

LOL, I just bought two from radio shack, one for volts and one for current. For some reason whenever I need a new meter, I can only find 3-400ma max :-[ Seems to be a curse.
The only regulator i have access to is the 7805. Ive used it with no problems for my BR but dont know what to change to get the proper value for the new diode.

http://www.laserpointerforums.com/forums/YaBB.pl?num=1198710347/13#13

 

[chido]

Get this meter:
http://www.sears.com/shc/s/p_10153_12605_03482345000P?keyword=craftsman+multimeter
I just got it a while ago, it can handle up to 10A and even though it's kind of cheap it seems to be pretty good, plus you can also take temperature measurements.

 

[Benny_Hill]

its funny you showed me that meter, i have that exact one from Canadian Tire, just a different colour For some reason mine never worked properly, but i dont think i tried the current test with it. The meters that i am currently using are pretty decent, when you push the button on the posative lead it turns on led lights or talks and tells you the reading. Pretty cool but the 400ma max sux


http://www.thesourcecc.com/estore/P...=Online&category=Multitesters&product=2218202

 

[rkcstr]

You don't necessarily need a new meter to measure current.  Just put a low resistance (less than 10ohm) high powered (ie >1w) resistor in series with the diode and measure the voltage across the resistor.  Divide the measured voltage (in V, not mV) by the measured resistance and you get your current in A (divide by 1000 to get mA).  If you use a 1ohm resistor, 1mV should roughly be 1mA.

Also, the LM317 will be fine, just use a small heatsink with it (caution though, the tab on the transistor is not ground, so don't touch it or it's heatsink to anything else!).  Your needs are approaching the limits of the LM317, so a regulator of higher output would be better, but if you don't have access to one, don't worry.

Also, if you're regulating current, you don't need to regulate voltage, the laser diode will draw the proper voltage.  Just use one regulator set to the proper output current.  If you're trying to do 1000ma, you'd need a 1.25ohm ( C(out) = V(ref) / R(set), or 1A = 1.25V / 1.25ohms ).   Radioshack doesn't carry anything really close to a 1.25ohm resistor except for a 1ohm 10W resistor, which is way overkill for power rating and would output 1250ma, but it would work just fine.  You could also parallel a number of resistors get close, but the next lowest value in the 1/4 to 1W resistors is 10ohms, so you'd need 8 in parallel to get 1.25, 9 to get 1.1 and so on.

 

[Benny_Hill]

can i just do away with the regulator? Use resistors, a cap, polarity protection? i can run it at 3v or 6v. Im looking at what ever will make it work, so long as i dont kill it

also, the 7805 is the only regulator that i have in my box and is the only one i can get (offline)

 

[rkcstr]

can i just do away with the regulator? Use resistors, a cap, polarity protection? i can run it at 3v or 6v. Im looking at what ever will make it work, so long as i dont kill it

also, the 7805 is the only regulator that i have in my box and is the only one i can get (offline)

I totally looked over that you mentioned your Radioshack only has the 7805...

What's that about?? Go in there an smack them around, tell them they hardly have electronics parts as it is! Haha, anyway, seriously, I don't know where you are, but is there another Radioshack anywhere near you? Sometimes some stores have better selection than others. Or, try asking them or looking in your phone book for other places you could find parts. Anywhere that repairs electronics may be able to help you.

 

[Benny_Hill]

Its Canada, the Source by Circuit City (radio shack) was a cheesy result of a corporate buy out. They sell like 20 different parts, and thats aboot it

But if i can go with no regulator, im willing to give that a go. I usually do that for the reds. I just dont pay 70$ per diode normally and its got me hesitating once again. :

 

[ndrew2505]

i cant post links or id show you the page but i found this at merideth. its only 50$

The LDD-40 is a laser diode power supply that provides automatic current control (ACC) regulation up to 1.5 Amps. It comes as an assembled PC board and includes instructions for hook-up and current adjustment. Requires basic soldering and electronic skills. A multimeter, wire, and power source, along with your laser diode & heatsink is also needed for set-up.

SPECIFICATIONS:

Input Voltage: 4.5 to 6 VDC.
Input Current: 20mA to 1550mA, depending on output setting.
Output Current: 10 to 1500mA, user adjustable, 10 turn pot.
Regulation: ACC, automatic current control.
Dimensions: 2.0" x 0.7"

 

[ndrew2505]

sry for the double post. mods can delete.

 

[roSSco]

i cant post links or id show you the page but i found this at merideth. its only 50$

The LDD-40 is a laser diode power supply that provides automatic current control (ACC) regulation up to 1.5 Amps. It comes as an assembled PC board and includes instructions for hook-up and current adjustment. Requires basic soldering and electronic skills. A multimeter, wire, and power source, along with your laser diode & heatsink is also needed for set-up.

SPECIFICATIONS:

Input Voltage: 4.5 to 6 VDC.
Input Current: 20mA to 1550mA, depending on output setting.
Output Current: 10 to 1500mA, user adjustable, 10 turn pot.
Regulation: ACC, automatic current control.
Dimensions: 2.0" x 0.7"

http://www.mi-lasers.com/cgi-bin/sh...hstart=0&template=Templates/SearchResult.html