In this tutorial I explain some of the terms used by DIY'ers when talking about electronic drums and related accessories.
I try to add images when available to better support the definitions given.

Step 1: The Difference Between an Electronic Drum and an Acoustic Drum

Acoustic drums don't need a power source or an amplifier to produce sounds, they are by nature fairly loud and can be tuned.

Electronic drums:
They come in 2 categories:
Electronic pads or Acoustic to Electronic conversions.

The Electronic pads do not produce much sound other than the stick noise against the pad's material, (Rubber, Mylar, or Mesh) they need a module to produce the sounds and an amplifier or headphones. Some pads can be tuned.

The Acoustic conversions volume level depends on the material that is used on the batter head (the head that is hit by the stick) if Mylar is used then the same acoustic volumes are to be expected, if Mesh is used a lot less volume will be produced. Rubber is a little more noisy than mesh but a lot less noisy than Mylar.

In my previous tutorial I explain how to make an acoustic to electronic conversion with minimum alteration to your drums, furthermore you can make your own mesh heads or buy them from several different places all over the internet.

Step 2: Electronic Pads or Acoustic Drums Conversion?

This is a matter of choice and how much money and time you are willing to spend on your project.
Most of us DIY'ers do it ourselves to save money and to be able to say that we have accomplished something useful (at least for us). That said, there are no rules on how to make your electronic set, it can be all pads or all acoustic drums or a mix of both, it can be all done by you or you can buy some parts and make others, it doesn't matter, what matters is that you create a drum set that you can use and be proud of.

the pictures below show an electronic pad as well as an acoustic drum.

Step 3: Mylar Vs Mesh Heads

There has been a great debate when it comes to replacing the familiar feeling of Mylar heads with ANY other material. Roland discovered that mesh is a good replacement because it provides an excellent stick bounce and it is a lot quieter than Mylar, it lasts just as long and it seemed to work well with the electronic sensors they use in their sets.
A lot of people "convert" or "migrate" to electronic drums due to noise concerns, most of us don't have a rehearsal space or an isolated garage where we can play a regular acoustic set. That's when converting to electronics becomes the solution.
the advantages are:
Low noise level. You can even practice with headphones and the only noise will be stick noise against pads! not loud enough for the apartment/house next door to be bothered with.

Multiple drum setups. Most modules today come with many different sound sets emulating many popular brands and many sounds are very useful.

Practice tracks. Some modules even come with practice tracks in which you can play along, remove the drum track and even change tempos, those tools invariably will make anyone a better player.

Easy to record. Ask anyone who has recorded acoustic drums before and has had the opportunity to use an E-kit to record which one they rather use. Chances are they will rather use the E-kit because it's ability to be connected straight to a PA system or even a laptop makes it easier to record, there are no complicated microphone setups or multiple takes for every drum. Some E-kits even allow you to use drum software. This will be discussed on the following steps.

Step 4: Acoustic Vs Electronic Cymbals

This has been another issue for debate.
Many purists will refuse to play anything other than acoustic cymbals.
I can't blame them having played acoustic drums for over 20 years myself.
I'ts hard to replicate the nuances of the real thing with rubber and electronics.
I bet that argument is pretty similar to the one they must have had when only acoustic guitars existed and somebody "dared" to mention an "electric" guitar. Many years have passed and now both types of guitars coexist peacefully and in total harmony. (no pun intended). Many years have also passed since the first electronic sets and cymbals were created and today's market is full of excellent choices, that's is not to say that DIY'ers are left out. I will soon post a tutorial on making your own electronic cymbals with different variations and detailed explanations of course.
The pictures below show two different types of electronic cymbals
The Alesis cymbals are brass (real cymbals) covered with a coating that mutes their acoustic sound but retains the look and feel.
The Pintech are rubber (they have different models at different prices)
quieter than the brass cymbals but if you are going for looks then brass is the way to go.
There are many ways to convert an acoustic cymbal into an electronic one, YouTube is full of DIY'er examples on that subject.

Step 5: Piezo, Switch, Trigger??

What's a piezo? what are they referring to when they mention a switch, what's a trigger??

A piezo is a small disc that is coated with ceramic on part of it and copper, one lead is connected to the ceramic and the other to the copper when vibration is applied (pressure) it gets translated into an electrical impulse which "triggers" a sound in a drum module.
For a much longer and detailed definition check this:
http://en.wikipedia.org/wiki/Piezoelectric_sensor

A switch as it's name indicates, switches between 2 or more states, in the case of drums or cymbals it switches between on and off, and it's often used in combination with a piezo sensor in cymbals to produce a cymbal "chocke" or mute effect when the switch is depressed. For an excellent explanation of this check http://www.youtube.com/watch?v=W6HjxoNGhEU
by Racer52oline.
The images below show a piezo switch and different manufacturer triggers.
Most of them share the same principle: A piezo sensor attached to a body which in turn is mounted to the drum externally, my DIY triggers can be mounted internally or externally depending on your preference.

Step 6: Bridge Vs Trigger Trap

On the prior step we were discussing the different types of triggers available, I will discuss the different mounting options this time.

My prior tutorial explained a method of mounting the triggers inside the drum as the picture below shows. The second and third pictures show examples of trigger traps.

There are also triggers made to be mounted externally like on the second and third pictures
if you want to keep your acoustic sound but have the triggers going through A PA instead of mics or to make it easier to record.
Of course they can be bought at the store but we are here to learn how to do it ourselves aren't we??
my prior tutorial explains how to wire a double zone drum or cymbal but a single zone drum can be made utilizing one piezo and a mono 1/4 jack which can be bought at any electronics store for about $ 2 each. Store bought triggers $ 25 and up!!

Step 7: Cone VS Block

In my tutorial on how to wire a double zone drum I talked about a foam cone or a foam block.
Why the difference you may ask?
Well, the difference is the module's sensitivity. Roland modules work better when the head is having less contact with the cone. If you were to create a bridge and utilize a block instead of a cone and were using a Roland module, you may run into some issues due to the Piezo being read too high, therefore a cone is recommended and of course adjust your module sensitivity until you get only the desired results.
Alesis modules on the other hand work better with foam blocks where the head is in contact with the full surface of the block and transmits all that energy to the piezo. This info comes from 3 sources, the Roland forums, the Alesis forums and my own DIY experience building my set using an Alesis DM5 and and Alesis I/O and also dissecting my friend's store bought Alesis DM6 pads which contain a foam block and not a cone.
To make your very own foam block you can get one of those sand paper blocks, remove the sand paper and cut a block of roughly 2 in by 1 in, you could make a cone utilizing that block but you may need to have access to a milling machine. Foam cones can be bought over the Net. Also you can test with a foam block on a non Alesis module and see if it works for you.

Step 8: Drum Module, Drum Machine, MIDI TO USB Interface

A drum module is a device which allows the user to plug pads into it and when the user strikes the pads, the module translates the hits into a programmed sound which in turn gets sent to an amplifier or headphones. Many modules today have several features and come in prices from around $300 to over $1000. Roland, Alesis and Yamaha are among the most popular manufacturers.

A drum machine is the predecessor of the drum module. Usually a drum machine is a simple device in which the user can program certain patterns to play and has some control over the tempo. This is used to accompany guitars or other instruments when a drummer is not available or not convenient due to circumstances. Modern drum machines are now mostly software and are more sophisticated than their predecessors.

A MIDI to USB interface is a connection that allows a musical instrument to be connected to a computer and send the music as digital data that can be later edited with software.
A keyboard with USB connectivity is an example of a MIDI device. more recent drum modules have this capability allowing them to play dedicated drum software and making them much more versatile than any single acoustic set can ever be.
Pictures below are the Alesis DM5 (Drum Module), Roland TD12 (Drum Module) and the Alesis I/O (MIDI TO USB)

Step 9: Drum Software

On the previous step I mentioned that with a module with USB connectivity it is possible to play dedicated drum software.
Drum software is software made by companies that recorded real acoustic drums using many velocity layers (explained in next step) and several different drum sets and also includes recorded grooves than can be used to complement your existing music or to give you a starting point.

The advances in technology allow electronic drums to be light years ahead of what they were only 2 decades ago. Gone are the days where an electronic set had only one sound per pad and it was robotic and unnatural at best. Dedicated drum software changes all this by giving the user ultra-realistic sounding samples that can be used with several MIDI interfaces even the computer keyboard in some cases. This can then be recorded using the software of their choice and tweaked to their hearts content. Once recorded the MIDI information remains the same but the drum samples can be changed. For example, if you recorded with an 80's sounding set but later on decided that a 60's set works better for the song's mood, all you have to do is change the samples and voila! the same recorded drums now have a different sounding set!. This can be done with all drums or just the snare or bass drum or a particular cymbal. Think of all the possibilities!! Not only that, but you don't have to worry about tuning or microphones. All the hard work has been done for you. That is not to say that you won't have to change anything, but the samples should already be a great starting point.

Some of the most popular programs are:

BFD2
Superior Drummer
EZ Drummer
Steven Slate Drums (My favorite)
And others that I can't remember at the moment but I'm sure a quick search for "drum software" will bring up.
The different options bring competition and with competition comes quality.
some companies offer smaller more affordable bundles, not everyone needs 60Gb worth of samples and not everyone can afford to pay $ 300+.
A decent computer is required, check the manufacturer's minimum specs before buying any software, and also downloading ASIO4ALL will prevent latency (explained in the next step)

Step 10: Velocity Layers Crosstalk Latency Double Triggering?

Velocity layers are different hits at different volumes on a recorded drum track of the same drum.... huh???
When a software company records a drum, for example a snare, they will record the drummer hitting the snare from really soft hits = low velocity to really hard hits = high velocity. Sometimes an instrument (in this case the snare) can have over 90 velocity layers. This amount of samples combined with AMG (Anti Machine Gun) technology allows the software to play a slightly different sample every time the user hits the pad thus creating a more (Human) feel and providing for a sound much closer to the acoustic counterpart.

Crosstalk. Crosstalk occurs when a pad gets struck and the pad adjacent to it triggers as well. for example you hit the bass drum and the snare pad goes off too. This can be adjusted to reduce the offending pad's sensitivity and eliminate it's occurrence.

Latency. Latency occurs when a pad is struck and the sound is heard after a slight delay.
This can be really annoying to most players as it messes with the tempo. Most OEM computer sound cards are not designed to prevent latency due to the fact that when using software the sounds should be produced fast enough to not have any latency, but when connecting an external instrument, the time it takes for the signal to travel from such instrument to the sound card and to the speakers can be noticed if it's over 10 ms. To prevent this, the ASIO4ALL driver can be downloaded and installed (free on the net) and this optimizes resources thus alleviating most latency issues

Double triggering as it name suggests, occurs when a pads sensitivity is set too high creating that machine gun effect. the solution is to reduce sensitivity of the pad.
most drum modules and drum software have parameters for this settings and there is little variation in the way they name them. Of course when purchasing a module as well as with any other complex electronic device we should swallow our pride and read the manual!!
That is sure to save us from some headaches...

Step 11: Single Zone Vs Double Zone and Even Triple Zone.

One versus two... it depends, if they offer me two million dollars instead of one......
or if they offer me 2 more hrs of work instead of one.....

When it comes to drums most every drummer is going to say double zone.
Why? you may ask. Because with a double zone drum you can for example:
Play a tom sound and a cowbell, or have a cymbal and a choke function.
Some fancier modules even allow for triple zone. This I can see if you had a Ride cymbal where you'd want to have the bell sound, the bow sound and the edge sound.

Again you can buy double zone or triple zone drums as well as cymbals....

Or you can make them!
Before you buy or make anything, be sure your module supports it.
Some modules support 3 zones (on some inputs) not all 12 will be 3 zones for example.
Some modules support only 2 zones , and some modules are only single zone. READ THE MANUAL. Ask questions on the forums, ask me as well. Check EBAY for items for sale, a lot of the DIY process is knowing what to buy and what to make yourself, know what you are willing to do (how much time, energy and $$$) before starting a project.
Don't get discouraged if something doesn't work on the first try. like I said on a prior tutorial, I try to give the best explanation of what I did so I can save you from having to make the same mistakes I made.
If you have any suggestions for a tutorial or if you have any corrections/additions, let me know and I will update this instructable.
Thank you for reading and I hope your project comes out awesome. please post pics....