LED inlays

[LoneWolf121188]

This is carried over from this thread. Anyway, daveq, I dont exactly get the difference between series and parallel...can you explain?

[daveq]

A series circuit means that each LED is connected to eachother in a string. A parallel circuit would be when you run a "bus" wire out to all of the LEDs for the + and minus (two wires) - kinda like a ladder with the LEDs being the rungs.

I'll give you a link that should clear a lot of this up for you:

LED info

Just go to the bottom and click on the technical section and then browse that. There's a link in there called "Application notes" or something like that. That's a good one. There's another called "basics" or something like that - another good one.

Let me know if you still have questions.

[LoneWolf121188]

i think i got that...how does that help with power consumption?

Ive seen that site before, but i really dont like it...too much text, not enough diagrams and examples.

[daveq]

Try this page. It has more examples and diagrams.

When you use a series circuit, all of the current flows through each LED so if you need 15mA for each LED and you connect them in series, the 15mA flows through all of them. In a parallel circuit, you would need to supply 15mA to each "branch". For 10 LEDs, that would mean your power supply pumping out 150 mA in a parallel circuit.

Now, the advantage to the parallel circuit is that the voltage of your power supply can be much lower than a series circuit. A series cicruit requires the LED "on" voltage which is usually around 3.5V multuplied by the number of LEDs. For 10 LEDs, 10 * 3.5 = 35V. In a parallel circuit, the voltage needed is just the 3.5V.

There are tricks you can use like putting 2 LED's in series (7V needed) and then put 5 sets of those in parallel. It doesn't seem worth the trouble to me though.

So, to sum it up - if all of this is too confusing - I would recommend using a parallel circuit. That way you will have no worries about power supply voltage - a 9V will work or several AA's like I did will work. Just connect a resistor to each LED and then run the power to it. The resistor value (ohms) can be determined by the calculator on the site I provided the link to. If you have trouble, let me know. Use the section that says "Single LED". You will be replicating that circuit by the number of LEDs (10 or 12 usually).

Whew, I guess this stuff can be difficult to explain. When I have some time, I will try to do a better job of laying it out for you.

[Saber]

In order to waste as little battery power across series resistors, I would tend to use a series-parallel circuit for the reason that I mentioned in this thread several weeks ago:

http://projectguitar.ibforums.com/index.ph...opic=5300&st=15

If battery life is not an issue, then go for the simpler parallel circuit. If you're not too sure, experiment with the different options and their effect on battery drainage before making the final installation.

[LoneWolf121188]

ok, cool, i think i got it, thanks! now the problem is installing the LEDs...do you think a neck shop could send me a neck with a seperate fingerboard so i dont have to pull it apart when i get it? im not making the neck myself on this project.

did you put the wires in the truss rod channel or route a new grove in the wood? also, wheres the battery pack on your guitar? i didnt see it in the pics.

[daveq]

Using a parallel circuit might also make things easier for someone who's not too familiar with wiring since you won't have to keep track of alternating connections along the way.

Do not put the wires in the truss rod channel. For a dual action rod, you won't have the room anyway. You'll need to route a separate channel for the wiring in the fretboard. I use a dremel for this.

I don't know what to say if you're not planning on doing the neck yourself. It's going to be difficult to get what you want that way, I think.

Maybe leave this until you're ready to do a neck yourself?

[LoneWolf121188]

well, im in no hurry to build it, havent even started yet...figure ill give it a shot. ill try it out on a $10 neck first, then do it on the real thing.

where's the battery pack on your guitar?

[daveq]

It's behind the trem routing - towards the back end of the guitar. If you decide to go with AAA or AA batteries, decide on the holder that you want before doing any planning. I decided on the 2x2 holder instead of the 4 side-by-side.

A 9V will work and you can get the GOTOH battery boxes that are made for guitars. The only issue is that the 9V's are typically the worst at battery life. You can buy medical/millitary 9V's that have better life but they get expensive. It all depends on how much you care about changing batteries. If you don't care, then I'd go with the 9V's (probably the dual battery box) and parallel them. If you do care, then AA's are the way to go in my opinion.

[LoneWolf121188]

rechargeables are always an option too...my charger only charges AAA and AA batteries, so i think ill go with that...1.2v per batt x 4 batts = 4.8v for 12 LEDs...might be tricky...but with the AA batts you get 2100mAh per batt x 4 = 8400mAh, as opposed to 7.2v and 150mAh with the 9v (yes, a 9v battery is really a 7.2v). my only concern is getting enough volts to the LEDs to power them.

[jammy]

I have a 9v battery here with my tester on it - 8.2v

[daveq]

1.2v per batt x 4 batts = 4.8v for 12 LEDs...might be tricky

I just want to make sure that you understand whta you're dealing with on this:

4.8V would be fine for any number of LEDs as long as you are using a parallel circuit. All you need is enough voltage to get the LED to conduct and in most cases that is around 3.5V. If you use a serial circuit or a hybrid, then you're going to need more voltage.

I'm not sure why you're only getting 7.2V out of your 9V's - are they new? I seem to remember reading somewhere that 7.2V is what battery manufacturers consider the lower end of operation for 9V applications - I'll see if I can find info on that. You should see higher voltage than that on a new battery though - strange.

[LoneWolf121188]

I went to the energizer website...look here (on the left, click rechargables, NiMH, look under NH22). It says a 9v has 7.2v.

I got the thing about the voltage requirement, I dont know what I was thinking when I typed that. so for 1,000,000 LEDs, each with a voltage requirement of 3.5v, you only need 3.5 volts for the entire circiut (in parallel). your battery will drain instantly, but you only need 3 AA batteries.

[daveq]

I didn't know that some rechargables (maybe all) have a lower nominal rating. The alkalines that I use have a 9V nominal as most would probably expect.

for 1,000,000 LEDs, each with a voltage requirement of 3.5v, you only need 3.5 volts for the entire circiut (in parallel). your battery will drain instantly, but you only need 3 AA batteries.

Yes - any components wired in parallel (LEDs, resistors, ...) all have the same voltage applied to them. If you were to wire them in series, then you would need to start increasing your voltage on the power supply since there would be a drop in voltage for each component leaving less for the rest of the chain (I'm not getting into caps,... here to keep things simple). Try a little breadboard circuit from radioshack with some resistors and LEDs. Look at the specs on the LED packaging and make sure you know what voltage/current is needed and see if you can get it working. If you can do that (and understand what's happening), try simulating your entire fretboard on the breadboard. If it all works, you're ready to move on.

One thing I sometimes do is check the overall current draw with the entire circuit breadboarded. If it's close to what you expected, everything is cool. If you see some strange value, don't install anything until it's cleared up/fixed. Let me know if this is too confusing. I'm trying to help avoid having you install something that will work for a few minutes and burn out due to improper circuit design (too much current, ...). I don't want to scare you off though - it's really not difficult to check it.

[Saber]

I didn't know that some rechargables (maybe all) have a lower nominal rating. The alkalines that I use have a 9V nominal as most would probably expect.

An alkaline cell generates 1.5V.

A 9V alkaline battery is actually made up of six 1.5V cells in series.

A nickel cadmium (and similar rechargeable) cell stores 1.2V.

So six of these in series gives you 7.2V.

Break open the plastic casing of a 9V NiCad one day. You'll find six little cells tack-welded together.

[goth_fiend]

a quick question about the led inlays, what material do you actually use for the inlay? acrylic? plexi glass? im asking because im thinking of doing a chrome vine of life with blue led's in the leafs and on the sides

[LoneWolf121188]

I was actually thinking MOP. the MOP dot is bigger than an LED, right? My idea was to VERY CAREFULLY drill holes in the MOP the diameter of the LED, then sand the LED even with the top of the MOP. the hard part would be drilling the holes w/o cracking the MOP.

My other idea was to sand the MOP dots REALLY thin, then stick the LEDs under them. then you could get a really cool glow effect.

Plexiglass or acrylic would probably work too .

[imunwell2]

I was actually thinking MOP. the MOP dot is bigger than an LED, right? My idea was to VERY CAREFULLY drill holes in the MOP the diameter of the LED, then sand the LED even with the top of the MOP. the hard part would be drilling the holes w/o cracking the MOP.

My other idea was to sand the MOP dots REALLY thin, then stick the LEDs under them. then you could get a really cool glow effect.

Plexiglass or acrylic would probably work too .

I don't think you will have a problem drilling the MOP, just drill it slow, and start with as small of a hole as you can. I used a dremel bit to drill it, but the dremel bit has several cutting edges. A drill only has two, so you'll need to progress through the pearl slow.

[daveq]

Drilling MOP isn't too difficult - that's how I did the eyes in the skull. Of course, you'll need to be careful of the dust - wear a respirator.

I double stick taped my pieces to a piece of wood to hold it in place. You might be able to just hold it with your hands but I prefer not to.

If you only want the light to show in certain areas of the inlay, then you'll need to do something to handle this. For instance, the eyes in the skull I made will glow a bit around the sockets (not much though since there's a lot of black around the LED). So, if it's important to limit the light to a certain area, you'll have to experiment a bit.

Good luck. It will either be a very rewarding experience or something you'll curse to the end of time .

[LoneWolf121188]

Good luck. It will either be a very rewarding experience or something you'll curse to the end of time .

I think it will be rewarding either way, in final product or experience...

[LoneWolf121188]

i talked to a guy that has a degree in microwave engineering, he said that i should put them in parellel, then put a resistor in that has an ohm rating of voltage of one LED divided by total amps used. so for example, using LEDs with a rating of 1.5v and 20mA would be 1.5/(.02x12)=6.25 Ohms. Can someone confirm that?

[lovekraft]

i talked to a guy that has a degree in microwave engineering, he said that i should put them in parellel, then put a resistor in that has an ohm rating of voltage of one LED divided by total amps used. so for example, using LEDs with a rating of 1.5v and 20mA would be 1.5/(.02x12)=6.25 Ohms. Can someone confirm that?

No, that'll probably fry the lot, unless you're using a really low-voltage battery. First, you have to know the forward voltage drop of the LEDs you are using - it'll be in the manufacturer's specs, but in general, it's about 1.5-2 volts for Reds, 2-2.5 volts for yellows and greens or 3.5-4 volts for blue-greens, blues and whites. You then decide the running current for your LED - most max out about 20mA, some of the super-brights will handle 30, but I'd bias well below that to save on heat and resistor size (some of the superbrights are painfully bright even down to about 2 mA). Then for a parallel circuit, multiply the current for a single device by the number of LEDs in your parallel array - that's your total current . To find the value of the curent limiting resistor, subtract the forward voltage drop from the supply voltage (your battery), and divide the difference by the total current to get your resistance in ohms, and then multiply the same difference by the total current to get the resistor's power rating in watts. Or forget the math, and just go here: LED Calculator (Courtesy of Metku Mods) Oh, and if you're going to use a parallel circuit, make sure to use matching LEDs, or you're going to have problems. HTH

[LoneWolf121188]

actually, with 2 AA batteries (3 volts total), 1.5v for the LEDs, a 20 mA current and 12 LEDs, it is 6.25 Ohms. funny...

[lovekraft]

Great! If you're using reds, that should work fine, but most anything else is going to have a higher voltage drop. Obviously, you can't use blues or whites since you don't have enough voltage, but reds, oranges and most ambers should work fine. However, since battery voltage drops as they discharge, you may run out of voltage beore you run out of power. Let us know what kind of battery life you get out of it.

[daveq]

This is why I really don't like giving out resistor values, ... It's so much better to try to understand it before buying anything and certainly before installing anything. I'm glad to see that you're not taking this info and just running with it - asking questions is going to help you in a big way.

As far as the one resistor with paralleled resistors - I don't like doing it that way. Lovekraft mentioned the main reason why I don't like it - when you have so many LEDs in parallel without their own resistor - you run the risk of having one or more of them operate out of tolerance and really messing with the others brightness. If one fails open, the others will be affected and will brighten - shortening their lifespan. It's not a real big deal and not likely to happen but when installing them inside a neck, I like to be as cautious as possible. I use high quality (1 to 2 % tolerance) resistors - 1 for each LED and run them all in parallel. It's more work, more money, takes more space but I think it's the most reliable method.

I'm currently messing around with fiber again to see if I can come up with something workable without sacrificing size and appearance. I've seen many people use fiber < 1mm and I'm not sure if I like it or not. I'm used to the 3mm side dots that I've been using but I'm trying to see how large I can go without running into bend radius issues. I'll post info if I think I've found something workable.

The main advantage to using fiber is of course the ability to have all the electronics in the body where it's easier to maintain and replace components. It also provides a way to greatly minimize battery usage but there are many drawbacks as well (size of side dots being the big one for me).

Try reading the site that I linked you to and see if you can make sense out of the circuit choices. If you're still not sure, send me a PM, I'll try to guide you through it so you'll end up knowing more about it and feeling more confident in your choices.