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 10-30-2013, 03:49 AM #1
Flugufrelsarinn's Avatar
Member
 
Join Date: Dec 2009
Location: Texas
Posts: 41
Rep Power: 0
Flugufrelsarinn is just really niceFlugufrelsarinn is just really niceFlugufrelsarinn is just really niceFlugufrelsarinn is just really nice
Flugufrelsarinn Flugufrelsarinn is offline
Member
Flugufrelsarinn's Avatar
 
Join Date: Dec 2009
Location: Texas
Posts: 41
Rep Power: 0
Flugufrelsarinn is just really niceFlugufrelsarinn is just really niceFlugufrelsarinn is just really niceFlugufrelsarinn is just really nice
Default Max power output of an LM317 driver?

I am looking at doing a 12X build. The only issue is I am not sure if I will be able to build my own driver that will work.

Would it be possible to build a 480mA driver with an LM317 if I use a combination of 2x8.2, 47, 9.1 and 100[ohm] parallel resistors as the resistance to set the LM317?

I am not sure how to calculate the power dissipated by the load resistors. Do I use the 1.25[V] V_ref value, or the 9[V] input voltage?


Sorry for my grammar, I typed this on my phone.


__________________
300mW
200mW
50mw green
30mw keychain green
5mw ebay green

50mw blu-ray
Homebuilt ~120mw blu-ray
Homebuilt ~500?mw blu-ray
Flugufrelsarinn is offline   Reply With Quote







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







Old 10-30-2013, 04:54 AM #2
djQUAN's Avatar
Class 3R Laser
 
Join Date: May 2013
Location: Philippines
Posts: 1,128
Rep Power: 559
djQUAN has a reputation beyond reputedjQUAN has a reputation beyond reputedjQUAN has a reputation beyond reputedjQUAN has a reputation beyond reputedjQUAN has a reputation beyond reputedjQUAN has a reputation beyond reputedjQUAN has a reputation beyond reputedjQUAN has a reputation beyond reputedjQUAN has a reputation beyond reputedjQUAN has a reputation beyond reputedjQUAN has a reputation beyond repute
Send a message via Yahoo to djQUAN
djQUAN djQUAN is offline
Class 3R Laser
djQUAN's Avatar
 
Join Date: May 2013
Location: Philippines
Posts: 1,128
Rep Power: 559
djQUAN has a reputation beyond reputedjQUAN has a reputation beyond reputedjQUAN has a reputation beyond reputedjQUAN has a reputation beyond reputedjQUAN has a reputation beyond reputedjQUAN has a reputation beyond reputedjQUAN has a reputation beyond reputedjQUAN has a reputation beyond reputedjQUAN has a reputation beyond reputedjQUAN has a reputation beyond reputedjQUAN has a reputation beyond repute
Send a message via Yahoo to djQUAN
Default Re: Max power output of an LM317 driver?

for 480mA you'd need 2.604ohms

if you parallel all those resistors, you'd get 2.5969ohms for about 481mA but that's a lot of resistors to connect in parallel which won't look neat in a driver.

It would be simpler to use 2.7ohms and 68ohms or 3.3ohms and 12ohms in parallel. Both would be under 1% off of the desired value.

Also, 3.9ohms and 8.2ohms or 4.7ohms and 5.6ohms in parallel is still under 2% error from the ideal.

For the power calculation, use 1.25V as it will be the voltage across the resistors.

Last edited by djQUAN; 10-30-2013 at 04:57 AM.
djQUAN is offline   Reply With Quote
Old 10-30-2013, 08:11 AM #3
The Lightning Stalker's Avatar
Class 3B Laser
 
Join Date: Aug 2013
Location: MI, US
Posts: 2,654
Rep Power: 716
The Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond repute
The Lightning Stalker The Lightning Stalker is offline
Class 3B Laser
The Lightning Stalker's Avatar
 
Join Date: Aug 2013
Location: MI, US
Posts: 2,654
Rep Power: 716
The Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond repute
Default Re: Max power output of an LM317 driver?

The voltage drop will be the same, but the current through each resistor will be different. To
get the current, you take 1.25 / the resistor's value in ohms = I. Then you take V * I to get
the wattage dissipated by the resistor. I always derate the resistor by 1/3 when using
through-hole unless they are on a heatsink. Otherwise they tend to leave nasty brown marks
on the board. Let's say you went with the 2Ω7 and 68Ω combination. For the 2Ω7, the
current through it would be 1.25 / 2.7 = 463mA. 463 * 1.25 = 579mW. 579 * 3 = 1737mW.
So this one should be at least 2W. Do the same thing for the other resistor to determine its
value.
__________________
ALL NEW MEMBERS MUST READ THIS!!! --> http://www.laserpointersafety.com

"Where, now, is the way by which the light distributes itself" - Job 38:24

YouTube Channel
The Lightning Stalker is offline   Reply With Quote
Old 10-30-2013, 08:18 AM #4
The Lightning Stalker's Avatar
Class 3B Laser
 
Join Date: Aug 2013
Location: MI, US
Posts: 2,654
Rep Power: 716
The Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond repute
The Lightning Stalker The Lightning Stalker is offline
Class 3B Laser
The Lightning Stalker's Avatar
 
Join Date: Aug 2013
Location: MI, US
Posts: 2,654
Rep Power: 716
The Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond reputeThe Lightning Stalker has a reputation beyond repute
Default Re: Max power output of an LM317 driver?

Quote:
Originally Posted by The Lightning Stalker View Post
The voltage drop will be the same, but the current through each resistor will be different. To
get the current, you take 1.25 / the resistor's value in ohms = I. Then you take V * I to get
the wattage dissipated by the resistor. I always derate the resistor by 1/3 when using
through-hole unless they are on a heatsink. Otherwise they tend to leave nasty brown marks
on the board. Let's say you went with the 2Ω7 and 68Ω combination. For the 2Ω7, the
current through it would be 1.25 / 2.7 = 463mA. 463 * 1.25 = 579mW. 579 * 3 = 1737mW.
So this one should be at least 2W. Do the same thing for the other resistor to determine its
value.
__________________
ALL NEW MEMBERS MUST READ THIS!!! --> http://www.laserpointersafety.com

"Where, now, is the way by which the light distributes itself" - Job 38:24

YouTube Channel

Last edited by The Lightning Stalker; 10-30-2013 at 09:24 AM.
The Lightning Stalker 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 05:06 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