Build instructions for MeeBlip DIY Board Kit – Revision 1.31 SE

In this tutorial, we’ll walk step by step through the process of building the DIY board version of the MeeBlip. Keep in mind that, especially if you’re sourcing some of your own components, colors on capacitors and the like will sometimes vary.

If you like to check against a schematic as you work, you can download one:
Get the Hardware Schematics

Step By Step Assembly

	The new red MeeBlip board includes a 9VDC power jack instead of a USB connector. It attaches to the bottom of the board. The 1/4″ audio jack, MIDI connector and 3×2 programming header also connect to the bottom of the board.
	1. Let’s start by installing diodes. they’re polarized  and electricity only flows through them in one direction. First, install the black 1N4001 diode in the top right corner. Match the stripe on the case to the silkscreen. Next, install D17-D21. Again, match the stripe to the silkscreen. Solder in place and clip off the excess leads.
	2. Install D1-D16 for the switch matrix at the bottom – don’t forget to match the stripe to the silkscreen (they should all be pointing in the same direction). I find it easier to solder one row, clip the leads, and then install the second.
	3. Now we can move on to resistors. Resistors non-polarized, so it doesn’t matter which way around they go. We’ll start with the ones in the MIDI In and microcontroller sections: - R1 10K - R2 220 Ohm - R3 1 K - R4 10 K - R5 220 Ohm
	4. Install the resistors in the audio section on the left side of the board: - R6 1 K - R7 274 K - R8 10.7 K - R9 4.64 K - R10 23.7 K - R11 100 Ohm - R12 1 M
	5. Install the polarized capacitors. C2 (10uF) is installed with the negative leg (and stripe on the case) facing the top of the board. C3 (0.33uF), C14 (10uF) and C12 (4.7uF) are installed with the negative leg (and stripe) facing left.
	6. Install the yellow 0.1uF bypass capacitors next – C1, C4, C5 and C13. This is also a good time to install capacitors C6 and C7 for the crystal – both 0.22pF (on the parts card). They’re non-polarized.
	7. Install the remaining non-polarized capacitors in the audio section: - C8 (0.01 uF blue) - C9 and C11 (470 pF) - C10 (0.001 uF)
	8. Install Q1 (16 MHz crystal), IC5 (5V voltage regulator – bend pins at a right angle before inserting in the board) and LED1 (the negative -shorter- leg must be on the right side).
	9. Solder in place the sockets for IC1, IC2, IC3, and IC4. Make sure the notch on the socket matches the silkscreen. This will make things easier when you insert the chips.
	10. Attach the 4-pin DIP switch, 9VDC power connector, MIDI IN jack and 1/4″ Audio jack on the bottom of the board (so that they don’t get in the way if you mount your synth in a case). Optionally, you can install the 3×2 programming header – also on the bottom.
	11. Install the 9 potentiometers. They clip into place, but be gentle so you don’t bend any of the legs. Make sure they’re firmly flush against the board before soldering them into place.
	12. The 17 switches are next. Don’t forget the power switch in the upper right. I find it easiest to hold each switch in place while the board is clamped in a vise, and then solder a single leg before checking that it’s straight.
	13. Insert the chips, matching the notch on the socket to the notch on the chip (if the chip has a dot beside pin 1 instead, place it closest to the notch): -IC1 Atmega 32A microcontroller -IC2 6N138 opto-isolator -IC3 Analog Devices AD7302 dual 8-bit DAC -IC4 Microchip MCP6002 op-amp
	You’re done! Your board should look like this.

Testing your Newly Built Synthesizer

1. Attach a 9VDC center-positive power supply to the 2.1mm barrel jack connector. The LED should light (if it doesn’t, disconnect the power immediately and check that the chips are installed correctly and that all the parts are soldered).

2. If the LED lights, connect the MIDI Out of a controller keyboard to the MIDI In on the Meeblip. Set the keyboard to Channel 1 and play a few notes. The power LED should flash off as notes are received. If the LED doesn’t flash, check that the DIP switch (which controls the MIDI Channel) is set in “Omni” mode (all switches off).

3. The Meeblip has a default patch that is loaded at power up. You should hear it when you connect the Audio Output and play a few notes.

4. Here’s a link to an image of the front panel to help you figure out how the controls are mapped: MeeBlip SE Front Panel [PDF - V1/DIY Hardware]

MIDI Control Change Mapping

All of the Meeblip SE parameters can be controlled (or overridden) using MIDI CC commands.

The knobs start at CC 48:

CC 48: Filter Resonance
CC 49: Filter Cutoff
CC 50: LFO Frequency
CC 51: LFO Level
CC 52: Filter Envelope Amount
CC 53: Portamento
CC 54: Pulse Width/PWM Rate
CC 55: Oscillator Detune
CC 58: Filter Decay
CC 59: Filter Attack
CC 60: Amplitude Decay
CC 61: Amplitude Attack

The switches start at CC 64:

CC 64: Knob Shift
CC 65: FM off/on
CC 66: LFO Random (off/on)
CC 67: LFO Wave (Triangle/Square)
CC 68: Filter Mode (Low/High)
CC 69: Distortion (off/on)
CC 70: LFO Enable (off/on)
CC 71: LFO Destination (Filter/Oscillator)
CC 72: Anti Alias (off/on)
CC 73: Oscillator B Octave (Normal/Up)
CC 74: Oscillator B Enable
CC 75: Oscillator B Wave (Triangle/Square)
CC 76: Envelope Sustain (off/on)
CC 77: Oscillator A Noise (off/on)
CC 78: PWM Sweep (Pulse/PWM)
CC 79: Oscillator A Wave (Sawtooth/PWM)

A switch is off if its value is between 0-63, on if it’s 64 or higher.

Optional: 9VDC Power (Previous Black Version)

Prefer 9VDC power? You can add that jack by adding:

• 1N4001 reversal protection diode
• 0.33uF capacitor (polarized capacitors should be installed with the negative lead closest to the top of the board – the same orientation as C2)
• 9VDC power jack
• LM78L05 voltage regulator

Installation is visible below.

- James Grahame, with Peter Kirn