The main goal here is to cram all the parts into the narrow confines of the jack, so we don’t need to use an external box or enclosure.
In addition to the cable and jack parts listed in Part 1, here are some of the things you’ll need:
Following up on Part 1, it’s time now to get into the heart of the project:
In this video, I talk about how JFET’s work, then work up a circuit diagram (as shown at right).
Then, I prototype the circuit on the breadboard of my Radioshack Electronics Learning Lab, and finally play through the circuit to show how it sounds.
In Part 3, I’ll demonstrate how to assemble the circuit so that it fits entirely inside the jack.
Here are some useful resources and background reading:
A few months back, I purchased the ultimate unnecessary-but-awesome gadget: the iPad 2.
With the availability of apps like Amplitube, AmpKit, and Garage Band, it’s immediately obvious how this device can be an amazing guitar learning and practicing tool. I’ll talk more about that in another article. But before you can plug in your guitar, you need a special interface…
In part 1 of this 3-part video series, I introduce the project- how to make your own impedance matching, buffered guitar interface for the Apple iPad, iPod touch and iPhone. These iDevices all share a similar headphone/microphone jack specification, so this circuit should work with all of them.
I’ll show you why a simple unbuffered cable interconnect will sound terrible- because of the significant impedance mismatch between a passive guitar circuit and the iDevice mic jack. Also, the iDevice provides a 2.8V DC on the mic input to drive a microphone preamp, and as you’ll hear, this voltage totally screws up your guitar circuit.
This isn’t intended to be an ultra-high-fidelity interface. But trust me, it sounds good and costs very little. And the principals learned in this simple electronics project are the same as those required to make a guitar boost pedal like the Fulltone Fatboost.
In parts 2 and 3, I’ll explain all the electronics and show you how to assemble the interface, but for now, let’s get started:
And here’s some of the things you’ll need: