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 > Experiments & Modifications



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



Reply
 
LinkBack Thread Tools Display Modes
Old 04-05-2011, 01:45 AM #1
Jufran88's Avatar
Class 2M Laser
 
Join Date: Feb 2011
Location: Southern California
Posts: 573
Rep Power: 81
Jufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond repute
Jufran88 Jufran88 is offline
Class 2M Laser
Jufran88's Avatar
 
Join Date: Feb 2011
Location: Southern California
Posts: 573
Rep Power: 81
Jufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond repute
Default Tailcap current

So, I was experimenting with my laser and decided to measure the current at the tail cap. I set my DMM leads for the 10A setting and this is what I got:

Host: Solarforce L2 Gunmetal
Driver: Micro FlexDrive V5 @ 1.5A
Battery: LG 18650 unprotected @ current voltage of 4.10V



At the tail cap I am getting 2.25A. What is the relation of the tail cap current to the current flowing through the LD driven by a boost circuit?
Attached Thumbnails
Tailcap current-img_0868.jpg  


__________________
FS: 3A selectable test loads *IN STOCK* - link

405nm 455 mA BDR-S06J GUIDESMAN (G2 Drive) - link
445nm 1500 mA A140 SOLARFORCE L2 GUNMETAL (FLEXDRIVE V5) - link
445nm 1566 mA A140 SIPIK HK21 (G2 Drive) - link
473nm B&W Tek BWB-10-OEM - 10mW
532nm SKY Lasers DPL - 200mW
638nm 1071 mA GUIDESMAN (AMC7135) - link
638nm 1053 mA SS 26650 (AMC7135) - link

LED Maglite 3D DD SST-90 5700K w/ Aspheric lens - link
LED Maglite 3D XM-L U2 bin - link
LED Maglite 2D Triple XM-L U2-1C bin - link

My DIY LPM - link

Last edited by Jufran88; 04-05-2011 at 03:52 AM.
Jufran88 is offline   Reply With Quote







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







Old 04-05-2011, 02:33 AM #2
Toke's Avatar
Class 3R Laser
 
Join Date: Jul 2010
Location: Copenhagen
Posts: 1,111
Rep Power: 51
Toke has a reputation beyond reputeToke has a reputation beyond reputeToke has a reputation beyond reputeToke has a reputation beyond reputeToke has a reputation beyond reputeToke has a reputation beyond reputeToke has a reputation beyond reputeToke has a reputation beyond reputeToke has a reputation beyond reputeToke has a reputation beyond reputeToke has a reputation beyond repute
Toke Toke is offline
Class 3R Laser
Toke's Avatar
 
Join Date: Jul 2010
Location: Copenhagen
Posts: 1,111
Rep Power: 51
Toke has a reputation beyond reputeToke has a reputation beyond reputeToke has a reputation beyond reputeToke has a reputation beyond reputeToke has a reputation beyond reputeToke has a reputation beyond reputeToke has a reputation beyond reputeToke has a reputation beyond reputeToke has a reputation beyond reputeToke has a reputation beyond reputeToke has a reputation beyond repute
Default Re: Tailcap current

The boost circuit acts like a DC "transformer", as in turning low voltage high current, into higher voltage but lower current.
A buck driver does the opposite.

Quote:
What is the relation of the tail cap current to the current flowing through the LD driven by a boost circuit?
The tail cap current will be higher, you can expect it to be voltage difference*driver efficiency. The later is hard to predict.
__________________
100mW Odicforce kit.
App. 300mw MiniMag
App 120mW labby
Fan cooled 400mA 12X 405nm flashlight

532nm 150mW Labby.
532nm 50mW in flashlight

1.2W 445nm Yobresal
Basic laser building guide.
Toke is offline   Reply With Quote
Old 04-05-2011, 03:38 AM #3
Cyparagon's Avatar
Class 4 Laser
 
Join Date: Sep 2007
Location: Wisconsin
Posts: 9,141
Rep Power: 9321
Cyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond repute
Cyparagon Cyparagon is online now
Class 4 Laser
Cyparagon's Avatar
 
Join Date: Sep 2007
Location: Wisconsin
Posts: 9,141
Rep Power: 9321
Cyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond repute
Default Re: Tailcap current

Quote:
Originally Posted by Jufran88 View Post
What is the relation of the tail cap current to the current flowing through the LD driven by a boost circuit?
It depends on the supply voltage. The flexdrive supplies and draws (approximately) constant wattage. As the battery voltage falls, the driver will draw more current.
__________________
A problem well stated is a problem half solved.
Cyparagon is online now   Reply With Quote
Old 04-05-2011, 06:19 AM #4
Jufran88's Avatar
Class 2M Laser
 
Join Date: Feb 2011
Location: Southern California
Posts: 573
Rep Power: 81
Jufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond repute
Jufran88 Jufran88 is offline
Class 2M Laser
Jufran88's Avatar
 
Join Date: Feb 2011
Location: Southern California
Posts: 573
Rep Power: 81
Jufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond repute
Default Re: Tailcap current

So, this is what I'm thinking:

driver power out = LD power in
Vbatt x Ibatt x Efficiency = Vf x If
(equation used at CPF)

Where,
Vin = Vbatt = voltage fed to the driver
Iin = Ibatt = current fed to the driver (tail cap measurement)
Efficiency = efficiency of the driver (could include other factors)
Vf = forward voltage of LD
If = current outputted from driver

In terms of efficiency of the driver (drlava states 80-95% efficiency for the flexdrives) we get:

Efficiency = (Vf x If) / (Vbatt x Ibatt) = (4.2*1.5)/(4.1*2.25) = .682 or 68.2%

Now, this is pretty low so I think the other factors that create loss in efficiency would be wire resistance, test probe resistance, battery resistance, but would that matter since the current values aren't very high?

And can we suggest that we can measure power dissipated from the LD or driver by using P=VI

So power dissipated by the driver:
P=VI = (4.1)(2.25) = 9.225W

and power dissipated by the LD:
P=VI = (4.2)(1.5) = 6.3W

Efficiency = 6.3/9.225 = .682 or 68.2%


Now I notice I get the same efficiency when I calculate it both ways. Coincidence? Can anyone else test this out and see what they get?

And I thought as the voltage falls that current will not go up but down, where if it hits minimum voltage the LD will just turn off.
__________________
FS: 3A selectable test loads *IN STOCK* - link

405nm 455 mA BDR-S06J GUIDESMAN (G2 Drive) - link
445nm 1500 mA A140 SOLARFORCE L2 GUNMETAL (FLEXDRIVE V5) - link
445nm 1566 mA A140 SIPIK HK21 (G2 Drive) - link
473nm B&W Tek BWB-10-OEM - 10mW
532nm SKY Lasers DPL - 200mW
638nm 1071 mA GUIDESMAN (AMC7135) - link
638nm 1053 mA SS 26650 (AMC7135) - link

LED Maglite 3D DD SST-90 5700K w/ Aspheric lens - link
LED Maglite 3D XM-L U2 bin - link
LED Maglite 2D Triple XM-L U2-1C bin - link

My DIY LPM - link
Jufran88 is offline   Reply With Quote
Old 04-05-2011, 01:03 PM #5
Cyparagon's Avatar
Class 4 Laser
 
Join Date: Sep 2007
Location: Wisconsin
Posts: 9,141
Rep Power: 9321
Cyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond repute
Cyparagon Cyparagon is online now
Class 4 Laser
Cyparagon's Avatar
 
Join Date: Sep 2007
Location: Wisconsin
Posts: 9,141
Rep Power: 9321
Cyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond repute
Default Re: Tailcap current

Are you calculating using open circuit voltage, or load voltage?

I can assure you it won't be 4.2V when you place a 2A load on it. You need to use the voltage while under load.
__________________
A problem well stated is a problem half solved.
Cyparagon is online now   Reply With Quote
Old 04-05-2011, 04:53 PM #6
Jufran88's Avatar
Class 2M Laser
 
Join Date: Feb 2011
Location: Southern California
Posts: 573
Rep Power: 81
Jufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond repute
Jufran88 Jufran88 is offline
Class 2M Laser
Jufran88's Avatar
 
Join Date: Feb 2011
Location: Southern California
Posts: 573
Rep Power: 81
Jufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond repute
Default Re: Tailcap current

Well, it would be load voltage and since there's no datasheet for A140 LD's I wouldn't know exactly the Vf at 1.5A. I'm just using the standard 4.2V for forward voltage of the LD.

Would anyone else like to participate and see what values they get?
__________________
FS: 3A selectable test loads *IN STOCK* - link

405nm 455 mA BDR-S06J GUIDESMAN (G2 Drive) - link
445nm 1500 mA A140 SOLARFORCE L2 GUNMETAL (FLEXDRIVE V5) - link
445nm 1566 mA A140 SIPIK HK21 (G2 Drive) - link
473nm B&W Tek BWB-10-OEM - 10mW
532nm SKY Lasers DPL - 200mW
638nm 1071 mA GUIDESMAN (AMC7135) - link
638nm 1053 mA SS 26650 (AMC7135) - link

LED Maglite 3D DD SST-90 5700K w/ Aspheric lens - link
LED Maglite 3D XM-L U2 bin - link
LED Maglite 2D Triple XM-L U2-1C bin - link

My DIY LPM - link
Jufran88 is offline   Reply With Quote
Old 04-05-2011, 07:35 PM #7
Cyparagon's Avatar
Class 4 Laser
 
Join Date: Sep 2007
Location: Wisconsin
Posts: 9,141
Rep Power: 9321
Cyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond repute
Cyparagon Cyparagon is online now
Class 4 Laser
Cyparagon's Avatar
 
Join Date: Sep 2007
Location: Wisconsin
Posts: 9,141
Rep Power: 9321
Cyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond reputeCyparagon has a reputation beyond repute
Default Re: Tailcap current

No no no... the battery voltage under load.
__________________
A problem well stated is a problem half solved.
Cyparagon is online now   Reply With Quote
Old 04-06-2011, 12:06 AM #8
Jufran88's Avatar
Class 2M Laser
 
Join Date: Feb 2011
Location: Southern California
Posts: 573
Rep Power: 81
Jufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond repute
Jufran88 Jufran88 is offline
Class 2M Laser
Jufran88's Avatar
 
Join Date: Feb 2011
Location: Southern California
Posts: 573
Rep Power: 81
Jufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond reputeJufran88 has a reputation beyond repute
Default Re: Tailcap current

Oh, got confused because you said 4.2V. My battery was 4.1V at the time and that's open circuit voltage.

Now that I have calculated it under load its 3.65V

So, now calculating for efficiency:

Efficiency = (Vf x If) / (Vbatt x Ibatt) = (4.2*1.5)/(3.65*2.25) = .767 or 76.7%
__________________
FS: 3A selectable test loads *IN STOCK* - link

405nm 455 mA BDR-S06J GUIDESMAN (G2 Drive) - link
445nm 1500 mA A140 SOLARFORCE L2 GUNMETAL (FLEXDRIVE V5) - link
445nm 1566 mA A140 SIPIK HK21 (G2 Drive) - link
473nm B&W Tek BWB-10-OEM - 10mW
532nm SKY Lasers DPL - 200mW
638nm 1071 mA GUIDESMAN (AMC7135) - link
638nm 1053 mA SS 26650 (AMC7135) - link

LED Maglite 3D DD SST-90 5700K w/ Aspheric lens - link
LED Maglite 3D XM-L U2 bin - link
LED Maglite 2D Triple XM-L U2-1C bin - link

My DIY LPM - link
Jufran88 is offline   Reply With Quote
Old 04-06-2011, 02:35 PM #9
Benm's Avatar
Class 4 Laser
 
Join Date: Aug 2007
Location: Netherlands
Posts: 7,428
Rep Power: 15904
Benm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond repute
Benm Benm is online now
Class 4 Laser
Benm's Avatar
 
Join Date: Aug 2007
Location: Netherlands
Posts: 7,428
Rep Power: 15904
Benm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond reputeBenm has a reputation beyond repute
Default Re: Tailcap current

Seems reasonable enough

Don't rely too much on current measurements when using switchmode drivers though. The will have input capacitors, but there is still an alternating component to the current they draw, and most multimeters cannot measure that properly.
Benm is online now   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 12:51 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