Laser with out a driver

[iknitsteel]

I was just wondering how it will affect a diode to run it just off batteries without a driver? Of course the batteries play the main role in this so I am using two AAA batteries in a pen build. I have the long closed can out of a GGW sled and it is hooked up directly to the batteries I am doing this a a experiment and as of now it seams pretty good. Just wanting so info if any one has any on this. Like will the diode die really fast? Any info is appreciated.


Justin

 

[Jaseth]

You have been a member for almost a year and you don't know the answer to this? Use the search button.. the driver protects the diode in many ways.

 

[Prototype]

Kenom did this with his teeny-burners, the batteries simply couldn't provide enough power to kill the diode, but enough to make it burn.

Edit: He used button cells though

 

[iknitsteel]

I guess that's why it is a experiment for me. It looks like the batteries can make it burn but not kill it I don't have a meter so I don't know how powerful it is. I know that the driver protects the diode I would never try this with a blu ray diode but I dont really care abotut this red diode that I get with every GGW I buy. I just want to see what happens.

Justin

 

[phoenix77]

You need to watch for power spikes from the batteries. Like Jaseth said, "USE THE SEARCH BUTTON" & here's one from Jerry (lasersbee) "THE SEARCH BUTTON IS YOUR FRIEND"...................rob

 

[lasersbee]

Ahherrmm... thanks Rob...

@iknitsteel...

find out the Max permissible current to run your LD at...

Check the current that the LD is sucking from the Raw Freshly charged
batteries...
If the current is below the Max permissible current then you should be OK
for your experiment...
If on the other hand the current is above the Max permissible current then
you will need to add in series a Current Limiting Resistor... Like an LED..

Jerry

 

[phoenix77]

Hey Jerry, you're gonna catch me soon in REP POWER. What the heck you been doin' buddy ?????????????? rob

 

[iknitsteel]

Thanks for all the info and sorry I did not use the search button I got lazy :tsk: And I have been a member for a long time but I laid dormant for a long time when I cam back the forum had switched!!! Once again thanks for all the help!!

Justin

 

[lasersbee]

Hey Jerry, you're gonna catch me soon in REP POWER. What the heck you been doin' buddy ?????????????? rob

I'm doin' GREAT...

What I've been doing is trying to help out the members on LPF...

Nah... you'll always have more reps than me....


Jerry

 

[phoenix77]

Not that it's a race or anything but you ARE closing the gap..................rob

 

[Slipstream]

Kenom did this with his teeny-burners, the batteries simply couldn't provide enough power to kill the diode, but enough to make it burn.

Edit: He used button cells though

He also used a 10180 3.7v

 

[LarryDFW]

Justin;

You can direct drive the Red diode, but you need a resistor to limit the current.

Put new batteries in the laser.
Start with a 1 ohm 1/2 watt resistor, and measure the voltage across it.

You are looking for 0.4 volts DC across the 1 ohm which is 400ma.

If it is less, then you can lower the resistance and try again.

Current (I)= Voltage (E)/R

LarryDFW

 

[yobresal]

I've done it plenty of times without ever killing a red laser diode. You won't get more than 150mW out of it though usually off of 2 AAA batteries. I am not saying this isn't dangerous, it just hasn't ever killed any of my red diode.

 

[iknitsteel]

Thanks for all the info guys I have had it for over a week now and seems to be doing fine :wave:

Justin

 

[Hemlock_Mike]

I did this long ago but used the impedance of aaa cells to limit the current. It still works but I don't recommend this unless you have done your homework and graghed the LD curves.

HMike

 

[Benm]

Yup, these things work.. as long as they do.

What will happen is that it runs below its capability, or fry once when you insert fresh batteries, and likely: both.

There can be some science behind these things, especially when using button cells with more or less known internal resistance, powering LED's in keychain flashlights and such. Laser diodes tolerate less abuse, but it can work with luck.