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ArcticMyst Security by Avery

Another Blast at making 445 nm laser

M

mikD

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Apr 1, 2009
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Hi everyone.
Though I would show my latest 'home made' laser based around the 445 nm diode (1 W) . I turned the body of the laser on a small metalworking lathe using an aluminium bar (1.5" (40 mm) stock diameter). The Aziz holder fits inside the front half and a 20 mm thread used to connect the head to the body. I made a very simple driver using just two capacitors on the input and output of a 'L78SO5CV' regulator. The driver cost less than £1 ($1.40) to buy the three components from an electronics outlet. I am currently using a 6V lead acid battery (from an old motorcycle) as the power source, with the regulator on the positive lead. I tried using two CR2 batteries inside the casing but these don't last and are quite expensive (as we are all aware). So this laser has leads extending out of the back connecting to the battery. In the images I have the laser connected to a PSU with digital readout for current and voltage. Notice that the read out on the PSU gives 5.8 V and 0.73 A (power usage 4.23 W). Most of this power is dissipated as heat through both the diode and the regulator.
 





M

mikD

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What happened to my pictures??? here is another go at posting them. They where there on the preview!
 

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M

mb300sd

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Be careful with that regulator! A L78S05CV is a higher amp version of a 7805 (5V fixed) voltage regulator... It has a > 1V dropout voltage, which is probably the only reason your diode is still alive. Get yourself a LM317 and a pot for a proper current regulator at about the same cost.
 
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M

mikD

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Yes I used LM 317 on my other lasers with a 100 Ohm 27 turn pot and a 47 uF cap. I find this one gives a steady 5V and can take the appropriate current without burning out the LD. I have blown a few 405 nm LDs using the LM 317, but that could have been due to the PSU I was using at the time and the crappy heat sink. But I can easily throw a LM 317 together in no time at all. So you would recommend that over the L78SO5CV circuit?
 
M

mikD

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Well I made a LM317 circuit with a 47uF cap and a 100 Ohm pot. The LM was fried after 30 seconds of use. I thought I had burned out the LD! Anyhow I remade the circuit and it went again. So I am back to the L78SO5CV with a 0.1 uF and a 0.22 uF cap each grounded but one to the input and the other to the output (the caps are non-electrolytic) ceramic and tantalium type. The LD is running at 1A and 5.6 V. Most of that power is turned into heat though.
 
M

mikD

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Merged consecutive posts

Nice one for posting the 'interactive' version of the periodic table of irrational nonsense, I haven't seen the comments before. I actually laughed out loud and the missus got startled at me guffawing.
As to the heat sink, yup, I had one attached. Nothing short of immersing in liquid nitrogen would save this one though, which I might try next b.t.w.

The LD has fried. Bugger I remade the LM317 circuit and it fried my laser So I'm after another LD.
 
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