DIY Laser Torch

Comidt said:

Daedal, did you buy the whole 10 pack from Aixiz or only one?
If you bought them all, would you consider selling one to me?
i don't want to buy 10 of them. :-?
Thanks
Jonno

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I bought packs of 10, I have a few extras... PM sent.

--DDL

WOW those LM317's in TO-39 size are EXPENSIVE!!!!

I ordered 5 of them before I I realised they were over 8 BUCKS EACH!!

Oh..well...

On the plus side..I didn't have to pay the 5 dollar fee because the order was under 25 bucks!..

80 bucks worth of components are on their way....

I'll have a "FEW" extra if anyone is interested..

maybe I'll build a few power supply kits to sell....

Larry

Good deal Larry. But I have to ask... $80?? On what? I know I'm not one to talk... my orders from DigiKey are usually in the 100's when I bunch things up and order extras. But considering the project here... seems like you bought enough for 10 or more projects! ;D

GL either way, and I hope you picked up some of the TO-92 packaged ones too... I think I noted that up there, didn't I? :-/ The TO-39 would be perfect, but the TO-92 are even smaller, but they are rated only to 100mA. So, the risk is all mine in this one, and as such I wouldn't want to advise people to use the same chip for fear of burning their diodes up. :-[

GL;
DDL

Yes..I did buy multiples of everything..
5-10 pcs each..
Plus the regulators in all 3 sizes!

it adds up fast...but 5 of the TO-39 sized was 40 bucks all by themselves....

the rest were the other sized regulatord pots Zenier diodes resistors,,,and a partridge in a pear tree...

Larry

Daedal said:

For our purposes, we now have a circuit that we can do whatever we want with it, and place whatever we want on it, already made to fit this flashlight! So I grabbed one of my smaller LM317 chips and two 10-ohm resistors. The resistors are from the RadioShack bundle pack. I wound the resistor terminals onto each other from both ends to make one 5-ohm resistor rated up to a half an amp. I soldered that in place between the Adj and the Vout terminals of the LM317, and then I soldered the POSITIVE LD wire to the Vout line. Yes, the same place where the resistors attach to, you can just use the same piece of solder.

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I believe the highlighted line above should read "then I soldered the POSITIVE LD wire to the adj line. Could you confirm Daedal as this is in conflict with your drawing below that was taken from your "DIY Homemade laser diode driver" thread.

BTW just got my LM317s in the TO-220 package and it is not gonna fit in that tight space without cutting the atttached heatsink off the LM317. Even then I am not sure it will fit. I will give it a go and post pics tomorrow to show what it looks like.

Cheers.

thanks geek; cant wait for some pics

@ xgeek: Thank you very much for pointing that out! THAT is exactly why it's good to look over my things... Please excuse my mistake, and I hope no one followed this instead of the DIY Driver guide. :-[

Very sorry guys, it's fixed now

Thanx;
DDL

I made my LD driver today and I struggled with the size of the LM317T and the cap it had to fit in.
Not sure if this is the best way but it worked for me  

First I had to remove part of the LM317 heat-sink with a dremel. As this LM317 can sink 1.5 amps and we are only pushing a max of 300mA I am sure it will be okay. Next I was not sure how best to mount the LM317 i.e on its back or pointing up. I went for pointing up but this means you have to increase the hole in the housing that holds the parts so it can stick through.

I don't have the AixiZ housings yet but I have around 23mm clear between the top of the LM317 and the first washer. I may need to trim a few mm of the AixiZ housing so it does not short on the LM317.

Anyway here are a few photos of how far I have got. All I need now are the AixiZ housings and the SenKat's LDs and I am good to go ;D

Daedal said:

If you connected to the PCB like I did and is pictured above:

After pressing the ‘circuit’ in place, it’s important to connect the outside ring to the aluminum body if you connected the wire like I did. You can just place a small piece of solder on the edge, or press a small wire between the PCB and the aluminum housing and then bend it onto the outside ring.

At this point it is smart to connect a DMM in there, place the batteries inside, and try it out to make sure things work.

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Hi Daedal,

I have a question regarding this part of the build. You say here to test the unit to make sure it works and I have but I am not sure if it is correct.

If I connect my DMM to the 2 wires I am measuring 5.6 volts. I thought it should be around 3v? Is it because there is no load ?

As I don't have any LDs yet I tried the LED that came with the torch as a test. If I add the cap and diode across the LED and test I get this:-

Voltage = 3.17 and the current draw is 172mA. Now the question is will the supplied current increase when I add a LD as 172mA is a bit low. Also will the voltage drop below 3v?

One last question. I have read in this post and the driver circuit post the you take advantage of the forward voltage drop of the diode to lose an extra 0.7 volts to get to around 2.3-2.8V going into the LD. Is this the diode across the LD or the LD itself. The reason I ask is that the voltage going to LED in the test above is the same with or without the diode across the LED. The only  way I can get a voltage drop is if I add another diode in series with the positive lead.

With a 0.7V drop off the 3-3.5V supply form the LM317, you have a margin of 2.3-2.8V going into the diode. Which is perfect!

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Not sure if things will change when I get the LD but I am keen to make sure it's all working as it should  beforehand

Many thanks in advance.

As Daedal has missed this question can anyone else out there help answer?

Many thanks in advance.

What is the value of those resistors you have wired in parallel, 20 or 30 ohms? If you do get around 170ma's with the laser diode, stick with it for longevity of the diode. You will still have a nice burner and a very nice beam. Even with the diodes rating of 130ma's, it will light an unsharpied safety match almost instantly.

You really won't know if everything is going to be perfect before you get the diode, but it does look like you are in the ball park. Since you have already built the circuit, I would temporarily add a silicon diode in series then test the current with the laser diode.

Xgeek --
I test using the old Cree style star LED. That way I find out if im in the park without endangering my LD.

Mike

Hemlock Mike said:

Xgeek --
I test using the old Cree style star LED.  That way I find out if im in the park without endangering my LD.

Mike

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Regular LED's are tolerant of being over-driven to a great deal. So just seeing if a Cree lights up, I'd say it's a very ball-park test indeed. Many LED lights over-drive intentionally, because even at 50% of life-span, the life of the light is still nearly "forever" as compared to the hours of runtime demanded by an average user. And that life-span is still phenomenal as compared to an incandescent bulb.

However, from what I've seen 3V LED driver circuits generally test out at 5.xV when not under load. So that seems right to me.

Mike, I might have misread you, do you mean testing with a LED in place to test the driver output under load? That's a much fairer test.

Thanks guys for the help. I am sure it is okay as all 5 circuits test the same. Roll on the LDs

Damn - I typed a whole reply to this and the system was too busy. It tossed my reply out again.

Nevermind --- Mike

Lol, I hate it when something like that happens. When I type a long reply I usually copy it first.