Looking for a new hobby. I could use a little help getting started if you don't mind

I have 0 experience with lasers. I'm fairly experienced with electronics. I've built plenty of circuits, but most of my knowledge is on the practical side of things. I usually just learn enough to stay safe. I've been reading threads here for a couple of hours, so I'm just barely starting to understand the concepts.

Anyway, I'm planning to build a laser. My plan for the battery is either 2 18500s in series or 1 18650. I also plan to build as much of it as possible. I'm hoping I'll be able to build everything but the diode and lens. Is this going to be possible? From what I've gathered, I need a power source, regulator, diode, heatsink and lens. Am I missing anything?

I'm having a hard time figuring out the appropriate regulators I might need for either 3.7-4.2v or 7.4-8.4v. When calculating mA output for a LM317 for example, how does input voltage affect the output? How can I find the output mA for a fixed input voltage?

For the diode, I know I should start out with visible light. Other than that, I don't really know. Should I just start with ripping out diodes from dvd drives?

Anyway, sorry for all of the noob questions. I appreciate any help or suggestions anyone has to offer. Sorry if this isn't an appropriate section.

You lose 3v with the LM317 as its voltage drop. So, figure your required voltage plus an extra 3v. To achieve a particular mA output, you take 1.25 and divide it by your desired mA output, and that will give you the ohm of resistor you must use. For example if I want 125mA, I would take 1.25 and divide it by .125mA and get a 10ohm resistor. I hope this helps. Also WELCOME TO LPF!!!

-Nute

I hear gardening is a great hobby this time
of year. Spring will be on the way soon,
so now is the time to think about starting
growing. I have some soil and a few seeds
if you need some.

seed = diode
soil = driver

Seriously, though, start reading through the
stickies.

can you please make an 'intro' thread in the welcome section?? read those from other new members to get the idea of an intro also its rather important that you fill in all your profile including general location and DOB.

We prolly have a member not far away and hands-on help is the best- plus you may find a member with an LPM and we all meter lasers free.

yeah ...read the stickies at the top of most sections-- place your Qs in the proper section )AFTER your search) and avoid double posting--

I have a +6 rep bump if you follow through--welcome from texas

Nute said:

You lose 3v with the LM317 as its voltage drop. So, figure your required voltage plus an extra 3v. To achieve a particular mA output, you take 1.25 and divide it by your desired mA output, and that will give you the ohm of resistor you must use. For example if I want 125mA, I would take 1.25 and divide it by .125mA and get a 10ohm resistor. I hope this helps. Also WELCOME TO LPF!!!

-Nute

Click to expand...

You mean 1.25 V / .125 A, right? not .125 mA. Just want to make sure we don't confuse him too early.

If you're using an LM317, don't expect much output with one lithium ion cell. at 4.2 V nominal, you can lose up to 3V ( I think 1.5V drop is the spec...), giving you only 1.2V MAXIMUM. You will need two cells to power anything well... If you haven't got Ohm's law down, memorize and study that one. It will make building your drivers a lot funner (since you'll understand what it's doing and why you can't push 3A out of one cell! )

Power P in Watts
Voltage V in Volts
Current I in Amps
Resistance R in Ohms

P = V * I
V = R * I
I = V / R
R = V / I

am I missing anything? Just remember, even if a power source is "capable" of high current output, if you don't have enough voltage, your current will be limited.

Welcome to the forums!

How to use LM317 driver:




BTW you're missing a "host" from your list of needed items.

See blue line in my signature

Yeah ^^^ that.
Thanks Eudaimonium! That should be simple enough to get anyone started.

Only thing I should point out is the 6 diodes in series is for Blu-Ray diodes. You only want to use 4 diodes for the test load for the red dvd burners and the blue ones. Right? ...technically, you shouldn't need a test load anyways if you know what parts to use and you have it set up right... better safe than sorry though.

SmexyPenguin, I started with ripping out a diode from a dvd burner. If it's just a reader, it won't be very powerful... but that might be a good start. I would honestly start with a burner diode though. It's super satisfying to get your first diode set up and have it burn something. Make very sure you get some proper eye protection before you even get the diode. There are some very affordable options out there.