Old 09-04-2008, 12:22 AM #1
Junior Member
 
Join Date: Sep 2008
Posts: 7
Rep Power: 0
NeedAnotherEye is on a distinguished road
NeedAnotherEye NeedAnotherEye is offline
Junior Member
 
Join Date: Sep 2008
Posts: 7
Rep Power: 0
NeedAnotherEye is on a distinguished road
Default Power Supply question

Hello all!

I've been checking out this forum for a while and I thank you for all the ideas! I had a Plextor DVD writer die on me, so I scrapped out the laser diode and am ready to have some fun with it.

I've built the LM317 current-limiting power supply posted elsewhere on this forum and it doesn't regulate the current like I expected... It's powered by four 'AA' batteries, it's hard-set for 103 milliamps output, and here's some tests I've performed: If I connect a 1-ohm resistor to the output, I get 103 milliamps on my ammeter. If I connect a 10-ohm resistor to the output, I get 103 milliamps. If I hook up my laser diode, however, I get about 40 milliamps on the ammeter and the laser diode doesn't do anything spectacular.

Shouldn't I get 103 milliamps when the laser diode is hooked up to this power supply?

Thanks in advance for the help, I appreciate it!


NeedAnotherEye is offline   Reply With Quote


















Old 09-04-2008, 01:43 AM #2
Bionic-Badger's Avatar
Class 4 Laser
 
Join Date: Oct 2007
Location: Oregon, USA
Posts: 5,478
Rep Power: 18104
Bionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond repute
Bionic-Badger Bionic-Badger is offline
Class 4 Laser
Bionic-Badger's Avatar
 
Join Date: Oct 2007
Location: Oregon, USA
Posts: 5,478
Rep Power: 18104
Bionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond repute
Default Re: Power Supply question

How is your circuit built?
__________________
You must spread some Reputation around before giving it to <person> again.
Bionic-Badger is offline   Reply With Quote
Old 09-04-2008, 02:10 AM #3
rkcstr's Avatar
Class 3R Laser
 
Join Date: Dec 2007
Posts: 1,368
Rep Power: 4403
rkcstr has a reputation beyond reputerkcstr has a reputation beyond reputerkcstr has a reputation beyond reputerkcstr has a reputation beyond reputerkcstr has a reputation beyond reputerkcstr has a reputation beyond reputerkcstr has a reputation beyond reputerkcstr has a reputation beyond reputerkcstr has a reputation beyond reputerkcstr has a reputation beyond reputerkcstr has a reputation beyond repute
rkcstr rkcstr is offline
Class 3R Laser
rkcstr's Avatar
 
Join Date: Dec 2007
Posts: 1,368
Rep Power: 4403
rkcstr has a reputation beyond reputerkcstr has a reputation beyond reputerkcstr has a reputation beyond reputerkcstr has a reputation beyond reputerkcstr has a reputation beyond reputerkcstr has a reputation beyond reputerkcstr has a reputation beyond reputerkcstr has a reputation beyond reputerkcstr has a reputation beyond reputerkcstr has a reputation beyond reputerkcstr has a reputation beyond repute
Default Re: Power Supply question

Likely you're not giving the LM317 enough voltage to regulate. For red diode, I think the LM317 may need more like 7V. The reason the resistors have the correct current is because they only have a 1V or less drop of voltage, so the LM317 has plenty excess voltage to regulate.

Also, you have the batteries connected in series, right? End to end, not in parallel (all positive ends connected to one wire, all negative to the other)? If in series, try adding another battery or two, see if that fixes the issue.
__________________
Laser drivers and Test Loads - rkcstr.com

Enter discount code "LPF" during checkout to save 10% off of the regular prices!
rkcstr is offline   Reply With Quote
Old 09-04-2008, 03:26 AM #4
Junior Member
 
Join Date: Sep 2008
Posts: 7
Rep Power: 0
NeedAnotherEye is on a distinguished road
NeedAnotherEye NeedAnotherEye is offline
Junior Member
 
Join Date: Sep 2008
Posts: 7
Rep Power: 0
NeedAnotherEye is on a distinguished road
Default Re: Power Supply question

Thanks for the replies!

rkcstr was right, I wasn't giving it enough voltage. *I connected the regulator to my model helicopter battery (11.1-volt LiPo) and it now gives a constant current whether the laser diode or 1-ohm resistor is hooked up to it. *Bionic Badger, I'd post a link to the current-limited regulator I used, but I can't post links since I haven't yet written enough posts. *It's in this forum, Daedal authored the post I referenced for my own power supply.

I'm sending the laser diode 130mA (??? watts power consumption) with this current-limited LM317 power supply, and I used to give it 108mA at 3.2 volts (0.3456 watts power consumption) using a voltage-regulated power supply. *I got more lasing power with the voltage-regulated power supply, but I imagine my laser diode was on borrowed time. *How much current should I give my laser diode? *It's scrapped out of a Plextor PX-708A DVD-RW drive, and it's mounted in a machined aluminum block to keep it cool (it hasn't even warmed up yet).
NeedAnotherEye is offline   Reply With Quote
Old 09-04-2008, 05:38 AM #5
Bionic-Badger's Avatar
Class 4 Laser
 
Join Date: Oct 2007
Location: Oregon, USA
Posts: 5,478
Rep Power: 18104
Bionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond repute
Bionic-Badger Bionic-Badger is offline
Class 4 Laser
Bionic-Badger's Avatar
 
Join Date: Oct 2007
Location: Oregon, USA
Posts: 5,478
Rep Power: 18104
Bionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond reputeBionic-Badger has a reputation beyond repute
Default Re: Power Supply question

Not sure how much those can handle, though you'll probably want to burn it out anyway for a more powerful diode anyway hehe. Just make sure you have enough cooling to keep it alive. Keep a record of how many mA you manage to push through it.
__________________
You must spread some Reputation around before giving it to <person> again.
Bionic-Badger is offline   Reply With Quote
Old 09-04-2008, 04:27 PM #6
Junior Member
 
Join Date: Sep 2008
Posts: 7
Rep Power: 0
NeedAnotherEye is on a distinguished road
NeedAnotherEye NeedAnotherEye is offline
Junior Member
 
Join Date: Sep 2008
Posts: 7
Rep Power: 0
NeedAnotherEye is on a distinguished road
Default Re: Power Supply question

Thanks for the reply! I'd go ahead and cook it, but this is the only diode I have at the moment. When I get another diode to replace this one, I'll go ahead and push it to its limits, heh! Although I don't know, since my wife's getting pretty mad at all the magazines we have that have pictures laser-cut out of them... It's fun what you can do when the laser's focused to a pinpoint! Well, fun for me, not my wife.

I scoured the Internet for specs on the diode that Plextor uses, but came up with nil. I went to Roithner Laser's website to make comparisons between the power requirements of different laser diodes within the 50-100mW range, but the power requirements range from about 85mA all the way up to 400mA! I really have no idea of the optical power output of my laser.

Is there a way to test the optical output of my laser diode based on performance references, since I don't have an actual laser power tester? For example, if I point it at a strip of electric tape, it will just start to burn through after about five seconds. And if I point it at a piece of newspaper that's colored black with a white back, the white side will start to darken after about 45 seconds with the laser pointed at the black side. The beam diameter is a little over 1/8 inch... How much optical power is required to do that?
NeedAnotherEye is offline   Reply With Quote
Reply





Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

























Privacy Policy | Advertising Disclaimer | Terms of Use


 


All times are GMT. The time now is 12:21 AM.


Powered by: vBulletin
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.
Search Engine Friendly URLs by vBSEO
Privacy Policy | Advertising Disclaimer | Terms of Use
Copyright (C) 2017 Laser Pointer Forums, LLC