True NEWB! First solder, circuit and laser - hopefully!

First, let's get this out of the way:

I don't know anything about electronics or lasers!!

Now that we've set the tone, I am ready to learn!


Although a stranger to lasers, I am no stranger to web forums. I didn't know anything about small motors or amphibious ATV's until the wonderful folks at 6x6world.org stepped up to help. I've been able to do valve adjustments, coil replacements, carb rebuilding, bearing and axle replacement, and so much more ONLY because of the expert help afforded to me on this type forum. I've also done several small jobs on my wife's vehicle that saved us a ton of cash thanks to bimmerfest.com! I appreciate and respect you folks that spend your precious time helping beginners like me!


I have been blessed with the opportunity to be a professor, mentor and tinkerer.. aka: stay-at-home-dad. Since having more time to explore things that interest me, I've been blazing the trail! lol - Not really, but I TRY. I started with a CB Radio, wanted more power and greater understanding and discovered Amateur Radio. I studied and tested for my Ham license, getting a tech license, KK4QJF. A portion of the amateur license is electronics, which spurred my interest again and during a search for simple DIY electronics projects I found the laser, and finally, laserpointerforums.com.


WHEW - so here we are.


First, I apologize in advance for what appears to be a mockery of lasers! It is not meant to be! This all happened today, very quickly after deciding I wanted to try the build. I will have to wait on the aixiz module delivery, but I went ahead without it. My driver is based on the youtube video for a $3 driver, only an adjustable voltage regulator and a resistor. Nothing here is meant to be permanent, I will spend more time and money building something I'm proud of, but I'll need help!

Parts:

Laser Diode from old school Pioneer DVR-220. 50mw 658nm per the manual.
LM317T adjustable voltage regulator
22k Ohm Resistor 1/2 watt
2 AAA batteries








Powered up the laser and nothing happened. DOAH. So I have some questions and beg for help! First, most information I could find recommended an LM317, the closest thing available at CellphoneShack (RadioShack) was the LM317T. Next, my understanding of how to find the appropriate resistor was to divide the LD output (50mw) into 1.25 as per the LM317. 1.25 / .05 = 25. The closest available at RadioShack was a 22k Ohm resistor. Also, the "k" in "22k" worried me, I never see anyone typing "10k ohm, 15k ohm" - I only see "10 ohm, 15 ohm." Is the "k" of importance? If I don't make sense I apologize! Next I tried to power the laser with 2 alkaline AAA batteries, I'm not sure this is appropriate either. AND last, I removed 2 diode's from the DVR. It is possible I soldered the infrared laser into my circuit but I would have still seen a dot on the wall if powered correctly, right?

I have been on this site searching all day, I am overwhelmed with very cool information and I've barely grazed the surface. I guess my ultimate goal here is to build a clean, handheld blue or green as a trophy piece, and to better understand basic electronics and circuitry. In the mean time, it would be cool to get this sucker LIT UP!

Thanks for reading yall

:gh:

close but no cigar....
K ohm mean 1000 ohms.

IIRC the LM317T just has a metal tag on it for better heatsinking

use ohms law to find the proper resistance required
Ohm's law - Wikipedia, the free encyclopedia

output is not a factor, you get current by Voltage divided by resistance[I=V/r], or any algebraic permutation of said formula

You want to try to find a spec sheet for the diode that states the "threshold" and "Max" current(your current should be close to max, if not over). Then use ohms law to find the right resistor(s) needed.

Also look at the thread "DIY Laser Driver" <- or something close that shows you step by step how to make a simple lm317 driver. There is an LPF google search bar at the bottom of the page. This is one of the most useful tools for finding info on LPF, use it BEFORE you post and the answers usually come flying at you at the speed of light!

RadioShack is becoming useless for any DIY electronics these days. I recommend using Digikey.com or Mouser.com for electronic components.

That being said, it looks like at first glance the LM317 may be wired incorrectly, as the "output" to the laser diode should come from the "Adjust" pin, and not actually the "output" pin. Nope - my bad, just an image flip!

Also, there's no lens or focusing assembly on a bare diode, so the output would be a wide beam, like that of a flashlight or LED.

Search "DDL Driver" here on the forums and you'll find tons and tons of posts of how to make this driver correctly.

Units of measurement in electronics:

n (lower case only) is for nano, meaning x 1/1,000,000,000
u (lower case only) is for micro, meaning x 1/1,000,000 - archaic form used "m" as well for capacitors; "mF" = uF, and mili is never used for capacitors.
m (lower case only) is for mili, meaning x 1/1000
K (or k) is for kilo, meaning x1000
M (caps only) is for mega, meaning x1,000,000

Ohms law is your friend; V = IR, or I = V/R, or R = V/I
It should be understood as such: I = the current PULLED by the load R when the voltage V is applied. You can never pull more current through a load than the resistance allows for a given voltage. In other words I = V / R -> 10Amps = 5Volts / 0.5Ohms. A 1/2 Ohm load will pull 10 amps at 5V input, but you can't push any more current through that load without increasing the voltage.

I appreciate yall's responses more than you know!

I obviously have a lot of very, very basic electronic theory to learn!

bdgreenb said:

close but no cigar....
K ohm mean 1000 ohms.

Click to expand...

LOL! More proof of my rookie status. Thanks bdgreenb for lending help!

Sigurthr said:

Ohms law is your friend; V = IR, or I = V/R, or R = V/I
It should be understood as such: I = the current PULLED by the load R when the voltage V is applied. You can never pull more current through a load than the resistance allows for a given voltage.

Click to expand...

Sigurthr, thank you SO MUCH for all the good information! I really do appreciate yall taking precious time to stop by and offer help.



I will do my part and attempt to answer all my own questions before I post more. Thanks again for the help, hopefully my next post will be a working model!

:gh:

Just a chime in on the Sigurthr's comment on LM317 wiring: It's correctly wired, the picture is just taken from the backside of the chip.

To the poster:

First of, howdy!

Second, here's a handy schematic you may want to print out or keep within reach:


Here's a handful of quick-draw advices for a newcommer:

Laser related: Always make sure where the laser is aimed when firing it up. Obviously.

Be careful when soldering leads to the diode. NEVER use alligator clips or other non-permanent methods of connection on the diode's pins if you have an output capacitor.

Never measure the current draw from the driver directly. Use test loads.

Be mindful of the currents you want out of your batteries. 9V batteries and AAA batts are probably worth jack for high-current lasers like 445nm, higher Bluray builds, Mitsubishi's red diodes and new direct greens.

You can totally test out diodes without a heatsink around an Aixiz module, just don't leave it on for too long.

Non laser related: Don't post identical threads, don't post multiple posts one after another, use "Edit" button, be nice (you got that part covered), don't pay much attention to the "reputation" system.

Also, whenever you need something, you can freely send me a Personal Message or two. I'll help you out as soon as I can.