Hi fellas, I've been putting together a new spindle light for my Taig Mill and I'd like it to be much brighter than before. In the enclosure, I have enough room to house 23 (yes, 23 lol!) LED's but I'm not positive about the best way to go about wiring them.

Some info:

23 white LED's
- forw. voltage 3.4
- forw. current 25 mA

Source will be a 9.5 volt Apple printer Power supply with 1.5 amps available

I've used the online calculators and I come up with 23pcs. 270 ohm 1/2 w resistors, but that's an aweful lot more parts to stuff in there. I bought one of those $5 puck lights that has 24 LEDs in it and they don't have hardly anything like that inside. They use those tiny little surface mount resistors, but there's like only 2 of them in there? Is there a cleaner way to do this with a lot less parts? I honestly don't mind soldering all that, but it just seems to be too much for what I'm trying to do.

Obviously I'm not an electronics guy, I just know enough to be dangerous - 

Thanks for the help and your time-
Dave

Hi Dave,

According to ohm's law  E=I*R and this transposes to R=E/I.

If you have 23 LED's each requiring a current of 25mA then that's 23*25=575mA.
If the p.s.u voltage is 9.5 Volts then R=9.5/0.575 or 17 Ohms.

So if you connect all the LED's in series (observing the correct polarity, of course) with a 17 Ohm resistor that should do it.

The resistor wattage is calculated as W=V*A or W=9.5*0.575 then that's 6 Watts (it will get warm in operation).

Hope this helps,

Tweakie.

Thank you Tweakie, definitely some good info there.

I've been looking around some more with others help and I can see I can build "arrays' or banks of LEDs and get by with less resistors as well.

I'm going to buy a breadboard/protoboard and start fooling around....uh oh......   

Thanks again,
Dave

You are quite right Dave, arrays are a much better solution as connecting them all like Xmas tree lights does have it's drawbacks.

Good fortune with your experiments.

Tweakie.

Cool project Dave.
 Just wondering.....if the PS is dedicated to this set of LED's only, could you put the resistor(s) in or at the PS end and have only led's in the doghnut ?
just curious.
Russ

or is the PS in there too....

Hi Russ,

Unfortunately that's what Tweakie was saying and it's not the "best" way to go as it's hard on the LEDs and it can get pretty warm as well. The best way I'm finding out (that I can personally do) is to have 7 "banks/arrays" of LEDs with a resistor for each bank. I think that I'll be able to pull that off even though I don't have much room to work with.

I wish I was good at doing circuit boards as this would be a breeze for someone who has a clue, lol!

Thanks again, Russ-
Dave

Hey Dave, why make one when you can buy a an LED campers light for around 10 bucks and just put a small voltage supply to it.
The one i have has 48 lights around it and i use to take pictures with my digital camera instaed of a ring light. YOu can also buy LED ring lights for say a microscope which come with a power suppply and variable intensity rather cheapy if you scan EBAY.Also check out the ones that you can put under a counter or shelves these days.
Just some ideas,
RICH

C'mon Rich, I'm disappointed in you.....now when do I ever make things easy? Seriously, I want this to be like my other spindle light housing, but it will now incorporate my laser finder as well. It's a form fitting spindle light that I designed around the Taig Spindle. I've actually looked at the round microscope lights but they're not a good fit because I can't reach the ER16 collet nuts for the cutters if installed.

As I mentioned above, I actually bought a $10 LED puck light just to tear it open to see how "they" did it and they use those tiny surface mount resistor arrays which there's no way that I can eeven begin to solder those! lol!

Thanks for the thoughts, my friend, but I've already been there, lol - 
Dave

I wish I was good at doing circuit boards as this would be a breeze for someone who has a clue, lol!

Hi Dave,

If I can isolation route PCB's so can you. Its real easy to do, just try it and see.  Would make a neat job !.

http://www.cooperman.talktalk.net/circuit5.wmv

Tweakie.

lol! I don't know tweaks, I'm going to have to do a little reading and a lot of learning about doing traces but I may just jump into it and see what I can come up with. Any advice on software to draw these things?

In the meantime, got my breadboard and did a little experimenting today,

Went with this array setup for the experiment: