Sunday, March 24, 2013

LED Guitar #2 - More Milling + Soldering

I need to drill the holes which connect wires from the LED cathodes to the fretwire. I have to drill a hole through the fret slot and then mill some small channels in order to connect the wire to my other channels I already milled. I also decided to deepen some of the original milled channels so that the resistors and solder joints fit inside flush (below the surface).

Here is the wire I will be using. I think it's 22 gauge solid core wire. 
Next to it is the smallest drill bit I could find.



Back side, you can see the small holes I just drilled.

 I milled little slots with the router bit on the left. 
I also decided to deepen the larger channels in certain spots with the router bit on the right. I tested the resistors and found them to be too fat to fit flush inside the previous channels.


 I should have finished all the milling before I cut off the sides and bottom of the fretboard. 
Since the fretboard now has tapered edges, I used double-sided tape 
to stick the fretboard onto this block of wood.

Now to remove the fretboard from the carrier block. 
This double-sided tape is a demon to get off once it sticks.
(Thus the putty knife.)

 You can see the tape residue. I just used my thumbs to rub and "roll" the sticky residue off. 
It's cleaner than trying to dissolve the tape residue with alcohol.

Alright, so a few days later I got around to putting the components in and soldering some of the connections. I got some 26 gauge stranded wire to use as my positive and ground lines up the middle of the fretboard. I like stranded wire because it is more flexible and durable than solid-core wire. I chose 26 gauge because it can easily handle the 200 mA this guitar neck might require, but it's also a very thin diameter.

 3.0 V white LEDs, 150 and 330-ohm resistors (1/4 Watt), small signal diodes (2N914), 
26 gauge stranded wire, and some heat shrink just in case I need some.

Close up of the small channels, and the sections I deepened.

First bend all the components at a 90 degree angle.

Twist the wires together. 
Be gentle, if you bend an LED lead too many times it can break on you.



Here's my soldering iron. It's a Weller, and they typically cost about $40. 
I like the variable temperature feature. It goes up to 40-Watts of power.
These are much nicer than the Walmart 10-Watt iron I used to have.
I really love the brass sponge tip cleaner. I will never use a wet sponge again.

Before^

 After^

 Before^

After^

It's a good idea to check all the LEDs at this point to make sure they still work.

OOPS! I soldered the diodes onto the LEDs before I attached the 22 gauge solid core wire that goes out the little hole!!! Not a huge problem though. I just used my de-soldering pump to remove most of the solder, and then twisted the copper wire around and then re-soldered the joints.

 Here you can see I attached the small copper wire to go through the hole.

It took a little work to get it flush with the surface. 
You don't want anything poking up above the surface.

Finally, I used a little bit of Krazy glue to help secure the LEDs inside once I inserted them and pushed hard with a screwdriver. The only thing I have left to do is solder the red and white wires for +9 V and ground.

 A few days later, I soldered the red and white wires.

 Hopefully this will give you a clear picture of how to do this yourself.


LEDs all on (underneath the bright lamp). 

 LEDs all on (bright lamp is off). 

The last thing I have to do before I can glue the neck together is to use hot glue to secure down the components and wires so everything STAYS in place when I try to clamp it all together. 

Notice the hot glue to reinforce where the red and white wires will go out through the neck. 

Another test run... gotta make sure they're still working before I glue it all up!!!


Monday, March 11, 2013

LED Guitar #2 - Drilling, Milling, etc.

I show here how I draw lines, drill holes, and mill the back side of the fretboard. Later on I will glue this fretboard onto the neck that I removed the old fretboard from. I chose to make a new fretboard rather than use the old existing fretboard. Drilling holes through the existing fret dots would not have worked very well. The plastic dots tend to chip and crack, and drilling a hole exactly in the middle of a 1/4" plastic dot is not very easy. Plus, purpleheart is just such a pretty wood, I just really enjoy using it.

Mark the centers with a pencil and use a center punch.

 Use a drill bit which cuts a 5mm hole (for a 5mm LED), this is about 0.191-0.193" in diameter.


Next, use a 1/4" forstner bit to cut a flat-bottomed hole on the back side. 
Only drill in about 1/16" deep. 


 Draw lines where you want to mill channels.







 Cut off the sides and bottom with a band saw.


 Semi-finished product. Ready to wire up and solder.

 Warm white 5mm LEDs from allelectronics.com


Unfortunately I did not know the forward voltage drop that these LEDs require, so I put them in series with 300-ohm resistor to measure the voltage drop with my multimeter. These particular LEDs measure a 3.0 V drop. Good to know when choosing resistors. It also measures about 3.0 V when I use a 600-ohm resistor, or even a 150-ohm resistor. The voltage drop should be more or less constant since it is a rectifying component rather than an ohmic one.

Resistance R= (9V-3V)/0.020A = 300 Ohms. Looks like I'll be using 300 ohm resistors for this one, and a 150 ohm resistor for the two LEDs in series on the 12th fret.

The resistor should be able to handle enough power. Power P=I*V = 0.020A * 6.0 V = 0.12 Watts.
So I should technically be safe using a 1/8 W resistor, but just to play it safe I will use a 1/4 W resistor instead. It would be a disaster if your resistor burned up inside of your guitar neck, so use a slightly higher power rating for your resistors.


LED Guitar #2 - Cutting fret slots on the table saw

I already made a more detailed post about how I use a fret saw table saw blade to cut a 0.023" kerf for fret wire. I won't go into the details here.

I had to make a new template out of aluminum. My first template was for a 25.5" scale guitar neck, and I needed a template for a 34" bass guitar scale neck. Once I made my template it was easy work. Here are a few pictures and a video:

Old template, new template 

 I made four purpleheart fretboards. If I'm going to make one, I might as well make several.


Here is what it looks like when it is finished.

Short video.

I shot this video in a cluttered garage, so sorry about the mess. Also, I don't demonstrate very good safety procedures...  Be careful whenever using a table saw. These things take off peoples' fingers every day. Lucky for me, it's only poking up about 1/8", and it's a very thin kerf, but I should be more careful anyway.