How to Build

the Audio Board

for Computing Culture's

Number Six

Jump to Section:

The Basics
Printed Circuit Board
Audio Output Circuit
Audio Input Circuit
MIDI In/Out
4 Controller Knobs

main audioBoard page
Number 6 wiki




The Basics

Make sure you have a Number Six! You can find instructions to build a Number Six microcontroller development platform here.

Order the Parts

Go to the parts list and order all of the parts. We suggest ordering from Digi-Key, but you are free to buy them from anywhere else you like.

Make the Printed Circuit Board

You can either send the Eagle files (.sch and .brd) to a website like Custom PCB and have them build it for you. Or, you may print the board and etch it yourself (much more fun!). To read about how to etch it yourself, take a look at How to etch your own circuit boards using Press and Peel Blue Transfer Film from Techniks, Inc.

First, follow the directions on the Techniks page to print your board onto blue transfer paper, and iron it onto your clean copper.

Then, etch your board in ferric chloride (you can get it from Radio Shack!)

And drill the holes. You should use a size 0.035" drill bit for most holes. The bigger holes can be drilled with 0.050" inches.

Finally, sand off the etch resist and you can begin to solder components to it!


Make the Audio Out Circuit

These are the components you'll need for audio out:



Here the five steps:

First, use the board layout picture to place the components in their places.

Then, push them through and solder.

Then, cut the excess leads.

Then, place the jumper on and insert the LMC6482 op-amp

Finally, solder on the audio input jack, and the output volume control.


This is how to set the jumpers:

Normally, you'll set the jumper here, to enable the audio output DAC (Digital to Analog Converter) with pin PA7.

If you make advanced software, that uses two audioBoards, you can set the jumper of one of them to the second position, to enable the audio output DAC with pin PA6.

Make the Audio In Circuit

These are the additional components you'll need for audio in:



Here are the two steps:

First, solder the components in.

Then, trim their excess leads


This is how to set the jumper for audio in. Normally, audio is digitized through ADC (Analog to Digital Converter) channel #4.




Make the MIDI In/Out Circuit

These are the additional components you'll need for the MIDI interface:

  • 6N138 optoisolator
  • 3 resistors, 220 Ohm.
  • 1 diode, 1N418 (or similar)

    Using the board layout as your guide, solder the 3 resistors and the diode. Pay attention to the orientation of the diode.

    Solder an 8 pin DIP socket to the board. Then, place the 6N138 optoisolator there.

    Now that the electronics of the MIDI ports are installed, attach MIDI ports. If you get into trouble, use this page as your reference.





    Make the Controller Knobs

    These are the additional components you'll need for the controller knobs:

    4 potentiometers. 3-terminal variable resistors with a resistance of between 1 KiloOhm and 1 MegaOhm. Try 50K pots from Radio Shack. They also sell knobs.

    Now that you have them, connect all three terminals of each one to the four triplets along the bottom of the board. The middle terminal of each pot should connect to the middle terminal of each triplet on the board.

    Expert Tip: If you like, you can connect the +5 and GND connections of the four potentiometers with wires, or on a subboard, and only run the middle terminals to the Audio Board.

    Links

    Audio Board main page

    Shifty's homepage

    Computing Culture's Number Six