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FrozenGate by Avery

LPRD: Laser Pointer of Reckless Destruction

Didactic Discord

Didactic Discord

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Hello everyone! I'm new to LPF, and have a question for you. I designed a laser, called LPRD, and I'm using Styropyro's $3 driver design to control the current going to a PHR-805T laser diode. I tried to find the numbers for resistance, voltage, and current, but I'm having trouble doing so. That brings us to my question, how does the LM317T work when a 10 ohm resistor is soldered onto the Vout and adjust pins? How much voltage comes out of it? Current? I would greatly appreciate all input on this matter. Thanks!
 





YvyY3.png


Where Vref is 1.25V, 125mA with a 10ohm resistor.
Little too much for a PHR diode, I would try and get a 9.1ohm resistor, or an 8.2ohm resistor.
 
ARG said:
YvyY3.png


Where Vref is 1.25V, 125mA with a 10ohm resistor.
Little too much for a PHR diode, I would try and get a 9.1ohm resistor, or an 8.2ohm resistor.
Click to expand...
Thank you very much! Just one more question: should this produce a fairly powerful beam? I'd love to burn stuff with it. Oh, I also forgot to mention I'm powering it with a 9-v battery.
 
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The beam and dot won't be very visible as it is near the end of the visible spectrum of light, but don't be deceived; it's much more powerful than it looks.
It will burn things when focused, should be able to light a match, pop a balloon ect.

Edit:

I can't math. Noticed a mistake in my post above. Don't use a 9.1/8.2ohm resistor as I said above, it will give you more current, which will definitely fry your diode. Get a 12, 13 or 15 ohm resistor; whatever you have around.
 
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ARG said:
The beam and dot won't be very visible as it is near the end of the visible spectrum of light, but don't be deceived; it's much more powerful than it looks.
It will burn things when focused, should be able to light a match, pop a balloon ect.

Edit:

I can't math. Noticed a mistake in my post above. Don't use a 9.1/8.2ohm resistor as I said above, it will give you more current, which will definitely fry your diode. Get a 12, 13 or 15 ohm resistor; whatever you have around.
Click to expand...
Would an aixiz ar coated lens focus the beam adequately?
 
Didactic Discord said:
One last question... What's the highest current I can give the phr-805t?
Click to expand...

I can't believe your original post was

"One last question... If the phr-805t runs optimally at 100mA, could I run it at 775mA?"

This was pulled from my email, which takes the original post to notify me :thinking:

-Matt
 
Hi everyone! I'm back, as puzzled as ever. I attached the + lead of a 9V clip to a switch, then another + to the 'in' on an LM317T. On the 'out', I attached a 10 ohm resistor. On the 'adjust', I attached a + going to the resistor. From the resistor/+ combo, I attached another + that led to a PHR-805T laser diode. I then attached a - to the diode and battery clip. I expected to feed the diode 125mA, but my Fluke multimeter told me I was giving it only 47mA. When I connected 2 9volts in series, it read 126mA. I have no idea why my laser didn't burn anything. Am I using the right diode, the right resistor? Can someone please explain what's going on, both what's wrong and how I can fix it? Please be extremely detailed. Thanks!
 
Your problem is with the battery! 9V batteries can't deliver much power (or current).

I don't know why everyone new to lasers runs out and grabs a 9V cell...

Try a six pack of AAs.
 
1.25 / 10 = 0.125, so 125mA is prettymuch dead on after compensating for any inaccuracies in the meter,
resistor, and the LM317. Are you getting any output at all? It should be fairly bright at 125mA.

The only thing I see lacking is possibly one of your batteries and the absence of a capacitor across the
diode.
 
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The pot is only there to have some adjustability. You don't need it at all.

Now take a look at the math for the LM317T and the power curves I linked to and use it to find out the
resistor values you are going to need.

You can even connect a bunch of resistors in series and parallel arrangements to get almost any
resistance you need. For resistors in series, add the values together. For resistors in parallel, add the
reciprocals of the resistances and then reciprocate the result.
 
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