Well, it's not a cartoon show, or a plastic toy, but instead it's a technique used by DJ's when doing mixes. Why do DJ's perform Transformers in a mix, you ask? Quite simple, because it's cool. A DJ does this by either quickly moving the fader up and down, or by using a mute button that some DJ mixers have.

    That's a bit subjective, once you play around with the effect with a variety of sounds, you'll get a better idea of where to use it. Some common types of sounds that work exceptionally well are strings or pads, but it also can really add some interest to an otherwise dull bassline, or even a rhythm track.

    The effect uses MIDI controller messages to achieve a reasonable facsimile of the DJ's technique. The controller that is used is #7, the volume controller, which modifies the specific channels volume. Now it's important to note that this technique will NOT work on all keyboards, since the volume controller isn't implicitly defined as changing the volume after a sound begins playing, so you will need to verify first that your sound source can do this. Secondly, not all sound sources can handle the amount of controller messages you're going to be generating, since it basically takes 3 messages to perform 1 mute (the initial on, the off, and then the subsequent on). And finally, keep in mind how this increased traffic affects all the other instruments on that MIDI out; you might also want to keep that in mind when laying out your instruments if you have multiple MIDI out ports on your interface.
    Ok, now that we have that out of the way, let's talk about how the effect is performed... The way I normally go about creating a transformer loop is as follows: First, I create a new track and fill it with controller message #7 value 127, every 30 ticks starting from time tick 0 (assuming 480ppm). Next, I fill the same track with controller message #7, value 0, every 30 ticks, starting from time tick 15. Make sure that you have the channel and port set to correspond with the sound you wish to transform, and now you can quickly hear the transform template by simply playing just the sound and the transform. If everything is set up properly, you should hear the sound quickly turning on and off, but still evolving as if the sound had never stopped playing. If you do, voila, you've done your first basic transform; if not, double check that the channel and port values correspond to the sound, and if it still doesn't work, then you might very well be using a keyboard that can't do it.

    Clearly the reason it doesn't sound cool is because you screwed up somehow... Just kidding! What you've done so far is just the technical side of the transformer, now it's on to the creative side. After listening to the template, you're sure to have an idea of the 'feel' of a transform, so now you simply go through the template and delete a volume 0 here, and a volume 127 there, thereby extracting a rhythm out of the transform. This is really the key to what you're trying to accomplish with the effect, which is to get a synth sound that pulses and moves with the rhythm, helping to carry the song along.

    Sure! There are tons of variations you can do with this effect, it's pretty much only limited by your imagination. To help get you going, here's a couple of my favorite things to do:
    Try making one transformer on the first sound source, then copy the transformer to a second sound source, and reverse the volume values (ie, change all the 127's to 0's, and vice versa). This will give you a REALLY cool cross-transformer effects between two sounds, which can be supercool when you use two sounds that are similar.
    Another variation to play with is the two volume values you use. While 0 and 127 create a dramatic transformer, you can sometimes get even better results by using values which are a little less extreme, such as 40 and 100. Now this depends on what type of sound source you're using, since each source tends to use the volume values differently, so keep that in mind when trying to move a transformer from one keyboard to another.
    Sometimes creating a transform with completely random volume values, and then using the first two tips described above can create some very unique and cool effects.
    Don't forget about MIDI controller #10, panning! You can really make some awesome transformers by sprinkling in panning positions. As mentioned above, don't get stuck in the 0 and 127 rut; play around with all the numbers in between.
    And finally, don't forget about using external effects processors in conjunction with this effect, especially multi-tap delays.

    That's it! I hope you find this trick handy, and come up with some riffs that get those creative juices flowing! If you have any comments or suggestions, or would like to share your tips and techniques with me, please feel free to contact me... Enjoy!