First Red Build (The Continuing Saga of DIY Goodness)

[Ghostchrome]

I've been working on a laser for several weeks now. LOTS of reading and learning new things... waiting on parts... putting things together... waiting for more parts...

I love it.

So I thought I'd share my experiences with you.

I've had some electronics experience waaaay back in high school, but nothing very spectacular. I know the basics, how to solder (badly), etc. I'm a tinkerer at heart and lasers are right up may alley. So why not build one, right?

I thought that a red laser would be perfect for my first project. The diodes are relatively cheap, which makes it a little less painful if/when you kill one.

So I bought a sled, ordered all the electronic components, and set out to work on my 660nm death ray.

I soldered together a rough LM-317 based DDL driver from this infamous diagram:

Thing went together relatively smoothly and the results can be seen here:

And it worked great. The only problem was that I was not maximizing the full potential of the diode. The max that I could achieve was 241mA, when i was reading that you could drive these diodes at 420mA and even up to 500mA.

I needed more power.

Unfortunately, like I mentioned, I am no electronics wiz, so I only had an idea of what I needed to do to the circuit in order to improve the output.... I had to decrease the resistance.

I ordered a new parts. Enough parts to make several LM-317 based drivers along with an assortment of resistors. I ended up going hog wild on the resistors and got some that were rated for 5 watts (just to be sure, you know? ), and it ended up being overkill because the resistors that I ended up receiving were huge - not at all meant for a compact circuit, but that's ok. This was going to be a labby anyway.

Along with the new parts, I ordered a solderless breadboard to aid me in my quest to build the perfect driver for my LPC-815. I plugged in the components, and after some resistor swapping I found that using two 1 ohm resistors seemed to get me in the neighborhood without exceeding the necessary current by too much. The pot would take care of the rest.

I built in a test load right into the circuit and let her rip. The pot seemed very touchy on the high end of things, but I dialed it in as close as I could and lo and behold, 417mA. Bingo.

I removed the test load portion of the circuit, desoldered my LPC-815 diode from the old driver, and plugged it into the new one.

I powered up the laser but I really didn't notice that much of a difference in power initially just by looking at the brightness of the dot, so I went to find a CD case that I used to test the laser with before and WOAH! The new laser starts the case melting instantly. I was very impressed with the power and surprised at how much hotter the Aixiz module got than it did before.

So that's where I am right now on the build. I found a combination of components that is working nicely (although the actual math still eludes me. Ideally I'd like to have the max current not exceed the LD's capabilities). Now I have to actually solder them together and find a host. I'll update as I go.

I'm hooked. I'm already planning my next build.

 

[bennett326]

welcome to the death of your wallet btw good job

 

[Ghostchrome]

welcome to the death of your wallet btw good job

Haha yeah. I see it happening already. Every time I get a package in the mail my wife gives me the evil eye.

"Let me guess, laser stuff?"

"Yeah..."

:crackup:

 

[midias]

Haha yeah. I see it happening already. Every time I get a package in the mail my wife gives me the evil eye.

"Let me guess, laser stuff?"

"Yeah..."

:crackup:

Man I think our wives must be sharing a brain ha ha ha

 

[Ghostchrome]

So on the driver, I've replaced the LM317 with an LM1117 and added an additional capacitor before the chip. I cranked up the amperage to 480mA.

She can burn through a CD case now at 6 feet. Not nearly as quickly as it does a few inches away, but I've got to say that I'm pretty impressed with it. Love that ruby red color.

Next up: Going to mess with a few different surface mount-style pots and see how low of a wattage rating I can go without frying something. I'd like to get a small of a package as possible, but I think it might start getting a little scary. heh. We'll see.

 

[Ghostchrome]

Beamshot.

 

[ShortyInCanada]

Very nicely done. I like how your lack of math skills doesn't slow you down.
And that darker red is very desirable.

And as far as having your wives involved in your deliveries...get your stuff delivered to where you work. You spend enough time there that deliveries should be easy to get. And you are available to sign for the bigger items too ! No more notices telling you to go to the nearest PO to pick something up.
:yh:

 

[Ghostchrome]

Very nicely done. I like how your lack of math skills doesn't slow you down.
And that darker red is very desirable.

Thanks, man.

Yeah, a math wiz I am not, and I've got no formal electronics background. So while I understand the gist of Ohm's law and stuff, some of the other math is a bit beyond me. I do love me some experimentation though.

The pot I am using now is rated at .5W, which is pretty much the largest wattage rating I can get with that package, and I think I might be pushing it already (I think I need a pot somewhere on the order of .6W). It doesn't get very warm though... at least in comparison to the LM1117 or the LD. In order to go to a smaller potentiometer package, I've got to drop down to about .25W. I think it should be doable. All the common boost drivers on the market today use those style pots. Who knows...it will be fun figuring it out.

And as far as having your wives involved in your deliveries...get your stuff delivered to where you work. You spend enough time there that deliveries should be easy to get. And you are available to sign for the bigger items too ! No more notices telling you to go to the nearest PO to pick something up.
:yh:

Yeah, I used to do that when I was employed.

 

[foulmist]

I've got to drop down to about .25W. I think it should be doable. All the common boost drivers on the market today use those style pots. Who knows...it will be fun figuring it out.

umm not quite right, I thought I should stop you before you burn it up!

you see when using linear driver like this, the resistor is dissipating heat based on how much current it flows through it.. so when running close to 500mA through it you will need at least 0.68W resistor..

with boost/buck drivers the set resistor can be a low wattage as the current is flowing through the coil and shottky diode, there you should be worried about those

actually if you plan on using linear driver check this site:
http://www.reuk.co.uk/LM317-Current-Calculator.htm

it's a resistor calculator for lm317/lm338 it will work for l1117 in the same manner.. it shows how much resistor wattage you need for the given current :beer:

 

[Ghostchrome]

umm not quite right, I thought I should stop you before you burn it up!

you see when using linear driver like this, the resistor is dissipating heat based on how much current it flows through it.. so when running close to 500mA through it you will need at least 0.68W resistor..

with boost/buck drivers the set resistor can be a low wattage as the current is flowing through the coil and shottky diode, there you should be worried about those

actually if you plan on using linear driver check this site:
LM317 Current Calculator - Electric Circuit

it's a resistor calculator for lm317/lm338 it will work for l1117 in the same manner.. it shows how much resistor wattage you need for the given current :beer:

Well, poop. I was hoping that I could get away with it, but yeah that makes sense. The reason I thought it might be ok (at least with a short duty cycle) is because my low rated pot seemed to be holding a much cooler temperature than the LM1117 in my tests (LM1117 was not heatsinked). I found it a bit strange but things seemed to be working ok in short doses.

Ah well. I was hoping to be able to squeeze a pot on there to give the driver a little bit more flexibility, but looks like it's going to be a no go. :/

 

[djayz]

Unfortunately, like I mentioned, I am no electronics wiz, so I only had an idea of what I needed to do to the circuit in order to improve the output.... I had to decrease the resistance.

I ordered a new parts. Enough parts to make several LM-317 based drivers along with an assortment of resistors. I ended up going hog wild on the resistors and got some that were rated for 5 watts (just to be sure, you know? ), and it ended up being overkill because the resistors that I ended up receiving were huge - not at all meant for a compact circuit, but that's ok. This was going to be a labby anyway.

Along with the new parts, I ordered a solderless breadboard to aid me in my quest to build the perfect driver for my LPC-815. I plugged in the components, and after some resistor swapping I found that using two 1 ohm resistors seemed to get me in the neighborhood without exceeding the necessary current by too much. The pot would take care of the rest.

I built in a test load right into the circuit and let her rip. The pot seemed very touchy on the high end of things, but I dialed it in as close as I could and lo and behold, 417mA. Bingo.

I removed the test load portion of the circuit, desoldered my LPC-815 diode from the old driver, and plugged it into the new one.

Thats the answer to my question.. I was wondering the same..
I'm totally modifying mine, I also have a hay-stack of reds, since they arnt going to sell XD you might know what i'm talking about "sigh" i am going to make all of them in different hosts, as soon as my aixiz modules arrive i'm good to go..

 

[Ghostchrome]

Thats the answer to my question.. I was wondering the same..
I'm totally modifying mine, I also have a hay-stack of reds, since they arnt going to sell XD you might know what i'm talking about "sigh" i am going to make all of them in different hosts, as soon as my aixiz modules arrive i'm good to go..

What was your question? Trying to find the exact resistor combination for your reds?

It's actually pretty easy. If you're using an LM317 based driver here's a formula you can use to figure it out. (I wish I'd known it when I built my first laser ) Using Ohm's Law:

V/I=R

1.25 / The desired current for your laser = The resistance needed

So if you wanted to set your red laser at 500mA the calculation would be:

1.25/.500= 2.5 Ohms

You can also solder a pot in series with the resistor to make the circuit adjustable, but you'll have to figure its minimum resistance into your formula as well.

Hope that helps.

 

[djayz]

Thanks.. And one more thing.. As its my first build too.. i didnt find any 1N4001's instead they gave me a couple 4007's and 10x 1N5398 and told me they had the same function.. Is it important that i use 1n4001 diode?

 

[foulmist]

1N4001 - up to 50V / 1.0A
1N4007 - up to 1000V / 1.0A
1N5398 - up to 800V / 1.5A

but yes they will all work for you..
and you don't actually need it.. the circuit will work without it

it's just for protection if you put the batteries in reverse

 

[djayz]

Thanks , Very much !
+rep

 

[DiogoNeves]

I'm taking some notes for my first project thank you