Amp

[WWC]

Hi. New here.

I would like to know if i can use a 5A amp meter and connect it like a standard amp meter in line with the current draw as standard amp meters are done, but in my LM317 driver circuit. I have a 2W blue diode in a housing and glass lens's.

Thanks

 

[ARG]

With an LM317 as a current regulator you can short the output with an ammeter to check the current.

 

[WWC]

Thanks for the comment AGR. Would it also work to have a amp meter in line continuously for a running check on the current? Or is a set it and forget it kind of thing.

 

[ARG]

You can, but I don't see the purpose. Better to set it and forget it.

 

[WWC]

This is my first laser go-around so i thought it would be good to see what i am putting through the diode at any given time. Keep an eye on it.

 

[djQUAN]

Although you won't see current spikes (which can still easily destroy a diode) on an analog meter, it does help to see if the battery is running low and the driver dropping out of regulation

 

[The Lightning Stalker]

Do you have some 450nm safety glasses?

 

[Things]

Hope you've got a beefy heatsink for that 317, the TO-220 version is only good for up to 1.5A and that's with a good heatsink.

 

[WWC]

I was able to get a 6.8, 2.7 and a 1.2 ohm resistors in 2w. Comes out to .74032 ohms by the calculator. This is a touch on the cautious side but i suspect it will be ok?

If this is turning out ok i may move into a LM338 instead of the LM317.

I am going to get beat up on this answer to Lightning Stalker about 450nm safety glasses. No i do not have a pair. There is no excuse good enough i could put here for this reason. I will order ASAP.

 

[Eudaimonium]

Using an amp meter in line without your driver's output is a bad idea, unless you have the leads soldered on and do not plan on removing them.

Problem is the non-solid connection to the diode. If it breaks for even a split second, you have a driver running with no power. That can not only destroy the driver, but it will also fully charge up the output capacitor. That moment when the connection is made again, capacitor discharges into your diode, frying it. So best case scenario is: only your diode is dead.

If you need to measure your current, use a test load, perform your measurement, and then use the diode and forget about it.

 

[WWC]

Would these be considered sufficient for safety glasses. If anybody has other suggestions iam all ears.

http://www.amazon.com/Metro-Shop-St...147297&sr=8-109&keywords=laser+safety+glasses

 

[The Lightning Stalker]

No reviews so they may or may not work.
Who knows? You won't go wrong with the
Eagle Pair™ from Survival Laser.

 

[WWC]

I ordered this pair just now.

Eagle Pair® 190-470nm & 660-760nm Laser Safety Goggles

 

[The Lightning Stalker]

Well, you really should have gotten the
190-540nm, as that would cover more of the
blue and green range, but those work great
at 405nm and 685nm. If the dot is bright
and you can see the beam when you get them,
then get the others as well.

 

[WWC]

Guess thats why i was asking for suggestions. Maybe it can be changed.