Laser pointer discussion. Read/write reviews of laser pointers and laser pointer companies. Learn about all types of laser pointers and lasers





Welcome to Laser Pointer Forums! If you are looking for a laser pointer or want to compare different laser pointer companies, you may want to check out the LPF Laser Pointer Company Database. The link will open in a new window for your convenience.








Green Laser Pointers by Category Blue Laser Pointers by Category Red Laser Pointers by Category
Yellow Laser Pointers by Category Violet Laser Pointers by Category Orange Laser Pointers by Category
Top Laser Pointers by Power - 1 Watt+ Top Laser Pointers by Power - 500mW+ Top Laser Pointers by Power - 250mW+
Laser Pointer Database High Power Laser Pointers Laser Pointer Diodes
Laser Technology Laser Pointer Parts Lasers by Wavelength
Top 10 Laser Pointer Companies Laser Pointer Company Database Visible Beam Laser Pointers


One laser store meets all your needs

























Go Back   Laser Pointer Forums - Discuss Laser Pointers > Lasers > Tutorials, Help & Repairs



LPF List of Laser Pointer Companies (link opens new window)



Reply
 
LinkBack Thread Tools Display Modes
Old 10-14-2008, 05:03 AM #1
Class 2 Laser
 
Join Date: Nov 2007
Posts: 321
Rep Power: 11
caleb is on a distinguished road
Send a message via MSN to caleb
caleb caleb is offline
Class 2 Laser
 
Join Date: Nov 2007
Posts: 321
Rep Power: 11
caleb is on a distinguished road
Send a message via MSN to caleb
Default Fixed DDL, help...

i built an adjustable driver but for some reaosn both teh PHR diodes i used seem quite underpowered. so i think iv made a mistake in either the driver or the DMM readings.
I think the easiest thing to do for now is to build a fixed, but how can i build one wich will have a definate current of 90mA?

If your nice enough could you make or find a schematic, or explain to me how to mod the adjustable DDL.

thanks dudes...


caleb is offline   Reply With Quote







LPF List of Laser Pointer Companies (link opens new window)







Old 10-16-2008, 05:02 AM #2
Class 2 Laser
 
Join Date: Nov 2007
Posts: 321
Rep Power: 11
caleb is on a distinguished road
Send a message via MSN to caleb
caleb caleb is offline
Class 2 Laser
 
Join Date: Nov 2007
Posts: 321
Rep Power: 11
caleb is on a distinguished road
Send a message via MSN to caleb
Default Re: Fixed DDL, help...

mans... :-?
caleb is offline   Reply With Quote
Old 10-16-2008, 03:13 PM #3
Tw15t3r's Avatar
Class 2 Laser
 
Join Date: Oct 2008
Location: Singapore
Posts: 266
Rep Power: 18
Tw15t3r is a splendid one to beholdTw15t3r is a splendid one to beholdTw15t3r is a splendid one to beholdTw15t3r is a splendid one to beholdTw15t3r is a splendid one to beholdTw15t3r is a splendid one to beholdTw15t3r is a splendid one to behold
Tw15t3r Tw15t3r is offline
Class 2 Laser
Tw15t3r's Avatar
 
Join Date: Oct 2008
Location: Singapore
Posts: 266
Rep Power: 18
Tw15t3r is a splendid one to beholdTw15t3r is a splendid one to beholdTw15t3r is a splendid one to beholdTw15t3r is a splendid one to beholdTw15t3r is a splendid one to beholdTw15t3r is a splendid one to beholdTw15t3r is a splendid one to behold
Default Re: Fixed DDL, help...

DDL driver is a constant current driver. The only component that's responsible for this is the LM317. And to set it up in current control configuration, is to connect a resistor to the output, and connect the adjust terminal to that other end of the resistor. Then connect the adjust terminal to the load of the circuit.

The LM317 works by ensuring a constant voltage, 1.25V, exists between the output and the adjust terminal. hence the current it outputs would be 1.25/resistance of that resistor only. It does not matter what the resistance of the load or other parts of the circuit will be. That's why it's called a constant current driver. (Get the datasheet for the LM317. They also explain several ways of using the LM317 along with how it works)

So if you'd want one with 90mA, make sure your power source is at least 6V (this is due to the dropout voltage of the LM317, i.e. the LM317 "eats" up some voltage itself), and then the resistance requirec would be 1.25V / 90mA = 13.9 ohms (rounded). Since they do not sell such precise resistors, it might be wiser to get a trim potentiometer and adjust till you get that resistance.
__________________
445nm 2800mW (9mm,X-drive) "Starlight Breaker" (link)
532nm 52mW (O-like module) MXDL (link)
532nm 25mW pen pointer
532nm 20mW pen pointer
532nm 6mW keychain pointer
650nm 18x DVD <in progress>
650nm 4mW Sure module in penhost
650nm 2mW pen pointer
Tw15t3r is offline   Reply With Quote
Old 10-17-2008, 02:25 AM #4
Class 1M Laser
 
Join Date: Sep 2008
Posts: 230
Rep Power: 9
LiveRock is on a distinguished road
LiveRock LiveRock is offline
Class 1M Laser
 
Join Date: Sep 2008
Posts: 230
Rep Power: 9
LiveRock is on a distinguished road
Default Re: Fixed DDL, help...

Hi

Use the online current calculator to get the ohms value:

http://www.reuk.co.uk/LM317-Current-Calculator.htm
LiveRock is offline   Reply With Quote
Old 10-17-2008, 05:32 AM #5
Class 2 Laser
 
Join Date: Nov 2007
Posts: 321
Rep Power: 11
caleb is on a distinguished road
Send a message via MSN to caleb
caleb caleb is offline
Class 2 Laser
 
Join Date: Nov 2007
Posts: 321
Rep Power: 11
caleb is on a distinguished road
Send a message via MSN to caleb
Default Re: Fixed DDL, help...

well i made a driver with a trim pot... but im prety sure my DMM says 90mA. i have more trust in a fixed driver then setting my own...
but thanks for that. 14ohms...
caleb 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











Loading








Green Laser Pointers by Category Blue Laser Pointers by Category Red Laser Pointers by Category
Yellow Laser Pointers by Category Violet Laser Pointers by Category Orange Laser Pointers by Category
Top Laser Pointers by Power - 1 Watt+ Top Laser Pointers by Power - 500mW+ Top Laser Pointers by Power - 250mW+
Laser Pointer Database High Power Laser Pointers Laser Pointer Diodes






Privacy Policy | Advertising Disclaimer | Terms of Use


 


All times are GMT. The time now is 12:54 PM.


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