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All schematics in KiCad format:

All schematics, PCBs, bills of materials in PDF format:


09/05/2011
Updated to include external (optional) EEPROM memory.

Digital Board:

Schematic:

PCB:

Components placement on PCB:

Bill of materials:


Optional. EEPROM extension:



09/015/2011
Updated to include external (optional) EEPROM memory.

Analogue Board:
Schematic:
PCB:
Components placement on PCB:
Bill of materials:

Input sockets:
Schematic:

LCD, MIDI In/Out, Controls:
Schematic:

Programming cables. ISP for Atmega, ICSP for PIC18F2550:
Schematic:

in the atmega programming cable, it shows four 220 ohm resistors. I built it with one 330 resistor and three 220. Does it matter?

elrules wrote:in the atmega programming cable, it shows four 220 ohm resistors. I built it with one 330 resistor and three 220. Does it matter?

It doesn't matter.

Hi Dmitri,

Thanks for all the hard work. These look great

Just wanted to know if there is any reason not to use the 4851s without the BATs and resistors, instead of the 4051s for the analogue board (like Synthex used on the all-in-one)? If I use them would I need to make any modifications to the digital board?

I also noticed that a couple of component values changed since the previous version. In particular, I was curious about the following:
L1 was 1mH, now it's 1uH
R9 was 47k, now it's 330 ohm.
There were also a couple of small changes as well as some 100 ohm and 47k resistors removed.

Since I have already bought the components, I was wondering if these changes are correct/significant.

Thanks,
6degrees.

6degrees wrote:Hi Dmitri,

Thanks for all the hard work. These look great

Just wanted to know if there is any reason not to use the 4851s without the BATs and resistors, instead of the 4051s for the analogue board (like Synthex used on the all-in-one)? If I use them would I need to make any modifications to the digital board?

There is only one reason for sticking with 4051s (and BATs) - DIP case versions of 74HC4851 ICs are not readily available in Europe and we have to pay a premium for delivery from USA to Europe, e.g. from Mouser it is around £15. Though SMD versions of 74HC4851 are available in Europe from Farnell with free delivery (with orders over £20): http://uk.farnell.com/9591532/semicondu ... tid=378592

I also noticed that a couple of component values changed since the previous version. In particular, I was curious about the following:
L1 was 1mH, now it's 1uH

I should have read specs for Atmega better in first place. 1uH is a correct value.

R9 was 47k, now it's 330 ohm.

My mistake, it should be 47k. I'll correct the schematic. (no harm to Atmega but ISP programming might not work with 330 ohm)

There were also a couple of small changes as well as some 100 ohm and 47k resistors removed.

100 Ohm resistors between Analogue and Digital boards aren't really needed. You only need to be careful(in ESD sense) when connecting boards together. When assembled, resistors in front of MUXers will protect from ESD.

Since I have already bought the components, I was wondering if these changes are correct/significant.

Not significant. See above.