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 09-09-2011, 09:20 AM #17
Bionic-Badger's Avatar
Class 4 Laser
 
Join Date: Oct 2007
Location: Oregon, USA
Posts: 5,478
Rep Power: 3157
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: 3157
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: Why do Batteries Have Voltage?

Quote:
Originally Posted by shintashi View Post
I'm still not sure why 9v or 12v of 200mA fries a diode where 3.7v of 200mA doesn't. I thought all the electrons were moving at near light speed. How can they be moving faster? I think this is the part of pressure I don't get, because in fluid dynamics, if you increase the pressure through a pipe, you get more speed, but electrons are all transferring at the same speed, so I thought you were simply transferring MORE electrons, but since Amperage is how many electrons, I dont understand why Voltage matters as long as you already have your Amps calculated.
It seems like a contradiction doesn't it? But the laws are absolute, so what actually happens?

Pretend you have a laser diode that has a forward voltage drop of 3.5V, and you use a 3.7V battery to power it. It works, and doesn't burn up. Then you hook up a 9V battery with the same current, why did it go up in smoke?

Well it's because you have two conflicting voltages. On one hand, your diode is supposed to only drop 3.5V; if the diode is passing current, you should be able to measure 3.5V across it. On the other hand, you have a 9V battery attached to the ends. This creates a voltage conflict: it should be 3.5V and should be 9V. This conflict means that something has got to give (i.e. break), and it can often mean that your diode (the weakest link) burns up when trying to eat up all that extra voltage.

So remember, your absolute assumptions (laws, parameters, etc.) MUST stay true in ALL cases. If there is an unavoidable contradiction (even if your professor writes the problem on the test wrong) there will be catastrophic damage.

In the 3.7V vs 3.5V case, that 0.2V just isn't enough to cause much damage. It might cause some heat in the diode, but probably not enough to damage it.



Last edited by Bionic-Badger; 09-09-2011 at 09:20 AM.
Bionic-Badger is offline   Reply With Quote







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







Old 09-09-2011, 02:34 PM #18
Class 1M Laser
 
Join Date: Aug 2011
Location: Northwest
Posts: 144
Rep Power: 13
shintashi is a name known to allshintashi is a name known to allshintashi is a name known to allshintashi is a name known to allshintashi is a name known to allshintashi is a name known to all
shintashi shintashi is offline
Class 1M Laser
 
Join Date: Aug 2011
Location: Northwest
Posts: 144
Rep Power: 13
shintashi is a name known to allshintashi is a name known to allshintashi is a name known to allshintashi is a name known to allshintashi is a name known to allshintashi is a name known to all
Default Re: Why do Batteries Have Voltage?

Quote:
Originally Posted by Bionic-Badger View Post
It seems like a contradiction doesn't it? But the laws are absolute, so what actually happens?

Pretend you have a laser diode that has a forward voltage drop of 3.5V, and you use a 3.7V battery to power it. It works, and doesn't burn up. Then you hook up a 9V battery with the same current, why did it go up in smoke?

Well it's because you have two conflicting voltages. On one hand, your diode is supposed to only drop 3.5V; if the diode is passing current, you should be able to measure 3.5V across it. On the other hand, you have a 9V battery attached to the ends. This creates a voltage conflict: it should be 3.5V and should be 9V. This conflict means that something has got to give (i.e. break), and it can often mean that your diode (the weakest link) burns up when trying to eat up all that extra voltage.

So remember, your absolute assumptions (laws, parameters, etc.) MUST stay true in ALL cases. If there is an unavoidable contradiction (even if your professor writes the problem on the test wrong) there will be catastrophic damage.

In the 3.7V vs 3.5V case, that 0.2V just isn't enough to cause much damage. It might cause some heat in the diode, but probably not enough to damage it.
so in some sense, voltage is the sideways pressure on the walls of the pipes, and pipe diameter is related to ohms, but when your circuit piece has thin walls - i.e., low "forward" voltage, it's the weakest link, and likely to blow out.

that makes me think wires have forward voltage. What is forward voltage, and do copper wires have it?
__________________

My Lasers:
405nm 600mW violet tactical
445nm Yobresal 1200mW
532nm Green Laser/Flashlight tactical 5mW
655nm Swiss Army Knife Mini-Laser 0.8mW
650nm my first" DIY failure" laser 100mW (?)


OEM Lasers OD 5+ 190-579nm Safety Glasses
shintashi is offline   Reply With Quote
Old 09-09-2011, 04:04 PM #19
bobhaha's Avatar
Class 3B Laser
 
Join Date: May 2009
Location: Sydney, Australia
Posts: 3,256
Rep Power: 360
bobhaha has a reputation beyond reputebobhaha has a reputation beyond reputebobhaha has a reputation beyond reputebobhaha has a reputation beyond reputebobhaha has a reputation beyond reputebobhaha has a reputation beyond reputebobhaha has a reputation beyond reputebobhaha has a reputation beyond reputebobhaha has a reputation beyond reputebobhaha has a reputation beyond reputebobhaha has a reputation beyond repute
bobhaha bobhaha is offline
Class 3B Laser
bobhaha's Avatar
 
Join Date: May 2009
Location: Sydney, Australia
Posts: 3,256
Rep Power: 360
bobhaha has a reputation beyond reputebobhaha has a reputation beyond reputebobhaha has a reputation beyond reputebobhaha has a reputation beyond reputebobhaha has a reputation beyond reputebobhaha has a reputation beyond reputebobhaha has a reputation beyond reputebobhaha has a reputation beyond reputebobhaha has a reputation beyond reputebobhaha has a reputation beyond reputebobhaha has a reputation beyond repute
Default Re: Why do Batteries Have Voltage?

They do, but it is extremely small... but they do have a decent sized resistance, estimating in the 1ohm range for 26 gauge wire for a 1m length.
__________________
Lasers!
10.6um - >40W CO2 Laser - 25W RF excited CO2 Laser*
685nm - Being built!
660nm - 250mW LOC PowerLight B50 Host - 100mW WL pulsar
635nm - 430mW C6 Host*
632.8nm - Red He-Ne laser ~1mW
593.5nm - Regal 5
542.8nm - Green He-Ne laser ~2.5mW
532nm - 620mW+ lasersman Firedragon III* - 100mW PGL-III-M from JETLASERS* - 70mW Rayfoss Host*
~~~ - 175mW Rayfoss Host - <5mW WL Core - 55mW DinoDirect review laser*

488nm - On the hoist
473nm - 2x CNI lab lasers ~40mW
445nm - 3W Big Boyz Laser - >1.1W Cree C6 Host - 650mW WL Arctic
405nm - 65mW GLP-405 Aquarius host - 160mW 6x Blu-ray MXDL Host
Total: 71,868.5 mW

Goggles!
Laser glow LSG-532-Sport protective eye goggles OD 7+ 190-532nm HIGHLY RECOMMENDED!!
Jetlasers wrap around 190-540nm OD4+ goggles*
Eagle Pair Red OD4+ goggles
Scopeguy20 Blublockers for 405nm lasers!

* indicates a review has been done, on this item.

Check out my How to Build a Selectable Dummy Load Thread!

Last edited by bobhaha; 09-09-2011 at 04:04 PM.
bobhaha is offline   Reply With Quote
Old 09-09-2011, 04:12 PM #20
Bionic-Badger's Avatar
Class 4 Laser
 
Join Date: Oct 2007
Location: Oregon, USA
Posts: 5,478
Rep Power: 3157
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: 3157
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: Why do Batteries Have Voltage?

Quote:
Originally Posted by shintashi View Post
so in some sense, voltage is the sideways pressure on the walls of the pipes, and pipe diameter is related to ohms, but when your circuit piece has thin walls - i.e., low "forward" voltage, it's the weakest link, and likely to blow out.

that makes me think wires have forward voltage. What is forward voltage, and do copper wires have it?
Water in pipes does actually have direct analogies to electricity.

Think of the strength of the walls of your pipe as the ability of the wire to withstand heat. Like too much current in a wire, if there is too much water passing through a small pipe it will burst.

Forward voltage is a parameter of diodes, resistors and other passives, not of wires. Wires are considered just conductors, in other words, any given point of a continuous wire will have the same voltage potential. It's like thinking of a pipe of water: the pressure at any given location of the pipe is the same. Pipes and wires still do have "friction"/resistance in them, even if extremely small, and this is why they can still burst or burn out if too much flow is through them. Superconductors have no resistance at all--like a frictionless pipe.

For a resistor, think of it as a pipe that is in the same shape as the resistor symbol: --/\/\/\/\/\--. If that is the case, the water entering the resistor would need to bounce back and forth between the sides to get out, expending some of the energy potential in the water, but maintaining the same amount of flow because what goes in must also go out.

The water analogy for a capacitor is a piston in a tube with a spring attached. The water can push the plate only so far compressing the spring. When the pressure is released, the spring will push water back out. This kind of thing occurs with the charge contained in a capacitor. Discharging the capacitor is akin to the spring being released.

An inductor is like a flywheel in the water. The water pushes it along and it starts to spin, but it is hard to slow the flywheel down if it is already spinning, and it'll continue to force the flow of water in the pipe.

Last edited by Bionic-Badger; 09-09-2011 at 04:14 PM.
Bionic-Badger 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 06:31 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