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 02-02-2009, 03:47 AM #1
Class 1 Laser
 
Join Date: Jan 2008
Posts: 68
Rep Power: 10
adcurtin is on a distinguished road
adcurtin adcurtin is offline
Class 1 Laser
 
Join Date: Jan 2008
Posts: 68
Rep Power: 10
adcurtin is on a distinguished road
Default Determining current.

I made an Lm317 circuit and I'm not sure which to trust measuring the current. With a test load for BR (6 1n4001s and a 10ohm resistor) i measure .850V, which should be 85mA. I measured the current with my multimeter's ammeter mode measured .220 amps with no other load. With the equation for lm317, using 38ohms, it should be giving 32mA. I'm powering this with a 9v and using a 10F tantalum cap on the output. Which should I trust for the output? (I hooked up a LPC-815 and could tell it was higher than 32mA).

Thanks,
Andy


adcurtin is offline   Reply With Quote







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







Old 02-02-2009, 08:47 AM #2
rog8811's Avatar
Class 3B Laser
 
Join Date: Jul 2007
Location: Berkshire UK
Posts: 2,749
Rep Power: 193
rog8811 has a reputation beyond reputerog8811 has a reputation beyond reputerog8811 has a reputation beyond reputerog8811 has a reputation beyond reputerog8811 has a reputation beyond reputerog8811 has a reputation beyond reputerog8811 has a reputation beyond reputerog8811 has a reputation beyond reputerog8811 has a reputation beyond reputerog8811 has a reputation beyond reputerog8811 has a reputation beyond repute
rog8811 rog8811 is offline
Class 3B Laser
rog8811's Avatar
 
Join Date: Jul 2007
Location: Berkshire UK
Posts: 2,749
Rep Power: 193
rog8811 has a reputation beyond reputerog8811 has a reputation beyond reputerog8811 has a reputation beyond reputerog8811 has a reputation beyond reputerog8811 has a reputation beyond reputerog8811 has a reputation beyond reputerog8811 has a reputation beyond reputerog8811 has a reputation beyond reputerog8811 has a reputation beyond reputerog8811 has a reputation beyond reputerog8811 has a reputation beyond repute
Default Re: Determining current.

Quote:
I measured the current with my multimeter's ammeter mode measured .220 amps with no other load.
If you are saying you put the meter, set on ma, across the driver output it will tell you nothing.

Have you measured the ref voltage to make sure everything is working correctly?


Regards rog8811

__________________
See all of my videos on Vimeo
http://www.vimeo.com/4454150

Lots of tutorials and information on lasers
http://www.rog8811.com/

In the land of the blind the one eyed man..... is most likely holding the laser
rog8811 is offline   Reply With Quote
Old 02-02-2009, 11:22 PM #3
Class 1 Laser
 
Join Date: Jan 2008
Posts: 68
Rep Power: 10
adcurtin is on a distinguished road
adcurtin adcurtin is offline
Class 1 Laser
 
Join Date: Jan 2008
Posts: 68
Rep Power: 10
adcurtin is on a distinguished road
Default Re: Determining current.

Ok, I did do that. There was a short in the circuit (vin to adj on the lm317). How do I measure the reference voltage? (voltage across Vin and Vout?)
adcurtin is offline   Reply With Quote
Old 02-03-2009, 07:57 AM #4
rog8811's Avatar
Class 3B Laser
 
Join Date: Jul 2007
Location: Berkshire UK
Posts: 2,749
Rep Power: 193
rog8811 has a reputation beyond reputerog8811 has a reputation beyond reputerog8811 has a reputation beyond reputerog8811 has a reputation beyond reputerog8811 has a reputation beyond reputerog8811 has a reputation beyond reputerog8811 has a reputation beyond reputerog8811 has a reputation beyond reputerog8811 has a reputation beyond reputerog8811 has a reputation beyond reputerog8811 has a reputation beyond repute
rog8811 rog8811 is offline
Class 3B Laser
rog8811's Avatar
 
Join Date: Jul 2007
Location: Berkshire UK
Posts: 2,749
Rep Power: 193
rog8811 has a reputation beyond reputerog8811 has a reputation beyond reputerog8811 has a reputation beyond reputerog8811 has a reputation beyond reputerog8811 has a reputation beyond reputerog8811 has a reputation beyond reputerog8811 has a reputation beyond reputerog8811 has a reputation beyond reputerog8811 has a reputation beyond reputerog8811 has a reputation beyond reputerog8811 has a reputation beyond repute
Default Re: Determining current.

Drawing shows how it is done. If the regulator is working the ref voltage will always be 1.25v.

Regards rog8811
Attached Thumbnails
Determining current.-ddl_circuit_test01_002.jpg  
__________________
See all of my videos on Vimeo
http://www.vimeo.com/4454150

Lots of tutorials and information on lasers
http://www.rog8811.com/

In the land of the blind the one eyed man..... is most likely holding the laser
rog8811 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 08:14 AM.


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