Red DIY DVD laser burner.

[photongeek]

Re: About this picture...

The dots and waves of bright and dark spots on this image, those are not necessairly dust spots. they are actually the waves of light creating disturbances with each other. what happens is there is some sort of impurity in the glass itself on the laser diode, be it a microscopic air bubble or what have you, it is blocking light at that spot. It will actually create destructive light interference. like this...

If you look at the bright spots, thats where the waves' phase is equal to (lambda); (2*lambda); (3*lambda); etc.... you will see really bright spots.
but if the phase is (lambda)/2 ; (3 lambda)/2 ; etc, the waves will be 180* out of phase and cancel each other out, creating the lack or light, or the dark spots.

You can look at Newton's Rings experiment for more information.


just some food for your mind

Yeah. I was never able to remove the spots and my laser died this morning. MAN!!!!
This diode seemed strange from day one and never performed like the others that did not show that peculiar pattern. It is now dim and projects a centered dark bar with light on either side.
It was only drawing 200ma from my Dorcy (cap and 3.8 Ohm resistor) with a voltage drop of 2.8 volts across the diode.
Anybody else have a similar failure?

 

[Kenom]

I havn't so far. crosses fingers!

 

[Kenom]

I figured my most recent post needed to be put into this thread since it's basically about the newest modifications I've done to make the dorcy even easier.

Ok. First, and most important. If you use something to prevent the board from shorting to the pins or anthing else metal in the casing you won't have to worry about shorting out the diode. The main reason for cutting the lines to the other contacts is so it won't come into contact with the back end of the Aixiz module.
Like so

Now I've changed the way that I do my modification to prevent damage by shorting to the star.
I now use a peice of 1/2 plastic tubing to mount the Aixiz on top of. This prevents the diode from shorting to the module by the back end of the module. Not to mention it's a lot easier to cut plastic down to size than to use the bronze on the back half of the module.



Second. The driver on the dorcy mini (jr) used to put out 350ma and now the drivers is putting out upwards of 400ma. It's important to test the current coming from the built in driver and make sure it's low enough and if it isn't use a limiting resistor in the top section like pictured. I ALWAYS use a 3.3 ohm resistor. Better to be safe than sorry!!!

Another VERY IMPORTANT MODIFICATION I'm doing is placing a small bit of plastic between the two pins on the diode to prevent the pins from shorting out to one another. I'll take some more detailed pictures for the entire modification from start to finish.

 

[Phazonx]

Is there anything I can add to the dorcy circuit to lower current?

I think 300 is too much.

 

[Phazonx]

I might sound retarded but, why is that resistor blue?

 

[member02]

i believe the blue resistors are only 2% tolerance

 

[Phazonx]

What is the simplest way to reduce current? What can I add to the flashlight circuit to reduce current?

 

[Kenom]

To reduce current down to 250ma use a 5 ohm resistor instead of a 3.3 ohm resistor. I use the resistor along with the built in circuit in the dorcy.

 

[Phazonx]

I don't get it, aren't resistors supposed to reduce voltage?

 

[Kenom]

and thereby reducing current as well.

 

[member02]

so, how do you go about reducing current and not voltage?

 

[Phazonx]

Ok, kenom, you can really help me on this one:

There is a 3 volt battery in the dorcy light. Why is the output 5 volts?

What kind of resistor do I need? I'm gong to go buy the required resistors right now ass soon as I find out which kind.

A quick reply would be fantastic

 

[Zarniwoop]

The Dorcy does have a 3V battery but put out up to 5V because it has a step-up circuit.
Those are great with alkaline batteries because while the battery voltage drops, the output voltage stays the same (to a point). With Lithiums, running them all the way down is a bad thing, and the protected ones will cut off (abruptly! - I thought I had a dead laser the 1st time it happened).

I'm using a 4.7 Ohm resistor with my current GB diode and Dorcy to get 250mA. They all vary a little. My previous GB diode wanted about 1 Ohm but that's unusual.
It's best to measure it but that should be in the ballpark.
I would use a 1 Watt though since 250mA at 3V is 750mA.

 

[Phazonx]

ok, I'm not a good person to figure this out.

Maybe you guys could calculate this for me. I have a deadline to do this for a friend before he leaves tomorrow.

Ok, without the LED thing, It read 5 volts. Wnen I tested current, it read 1.7 amps and started lowering?

I'm so confused right now, I need all the help I can get. Please help me find a solution of what kind of resistor I would need to run at 200ma @ 2.5 or 3 volts.

Help!! :'(

 

[a_pyro_is]

Phazonx, as a member here once posted "you have to read to succeed."

This link should help you:
http://www.facstaff.bucknell.edu/mastascu/eLessonsHtml/EEIndex.html

I understand you're feeling pressed for time but that's how mistakes are made. There aren’t too many people here who will spoon feed you the answers, as that wouldn’t allow you to learn anything.

Again, I understand time is short so let me try to help you.

I’ve never built a laser into a Dorcy, but from what I understand it’s a boost circuit. And as Kenom has told us, if you add a 5 Ohm resistor in series with the laser diode it will supply around 250mA which is a pretty good number in my experience for these 16X sony diodes. So if you're wanting 200mA I’d suggest you start with around 8.25 Ohms (that’s four 33 Ohm in parallel) or so and measure the current. (Measure the resistance before you solder it in, then measure voltage drop across the resistor and divide the voltage drop across the resistor by the resistance.) if the current is too low, lower the value of the resistor and try again. Like 7.33 Ohms (three 22 Ohm in parallel), or 5.5 Ohms (four 22 Ohm in parallel)

If you have a dummy load you can try that first to get in the ballpark.

Someone with experience with these Dorcy boost circuits please chime in if I’m way off here.

 

[deshisk8tr]

where do i get an axiz laser housing unit in the usa.