Latest MegaDrum schematics. 32 inputs.

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Latest MegaDrum schematics. 32 inputs.

Postby dmitri » Thu Jul 17, 2008 11:35 pm

All schematics in KiCad format:
megadrum32 schematics kicad.zip


All schematics, PCBs, bills of materials in PDF format:
megadrum32 schematics pdf.zip



09/05/2011
Updated to include external (optional) EEPROM memory.
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Re: Latest MegaDrum32 schematics. 32 inputs.

Postby dmitri » Thu Jul 17, 2008 11:40 pm

Digital Board:
digital_board_kicad_small.png

Schematic:
digital board-sch.pdf

PCB:
digital board-brd.pdf

Components placement on PCB:
digital board-brd components.pdf

Bill of materials:
digital board components list.pdf


Optional. EEPROM extension:
i2c_eeprom_small.png

i2c eeprom.pdf


09/015/2011
Updated to include external (optional) EEPROM memory.
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Re: Latest MegaDrum32 schematics. 32 inputs.

Postby dmitri » Thu Jul 17, 2008 11:41 pm

Analogue Board:
analogue_board_kicad_small.png

Schematic:
analogue board-sch.pdf

PCB:
analogue board-brd.pdf

Components placement on PCB:
analogue board-brd components.pdf

Bill of materials:
analogue board - components list.pdf
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Re: Latest MegaDrum32 schematics. 32 inputs.

Postby dmitri » Thu Jul 17, 2008 11:42 pm

Input sockets:
input_sockets_kicad_small.png

Schematic:
input sockets.pdf
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Re: Latest MegaDrum32 schematics. 32 inputs.

Postby dmitri » Thu Jul 17, 2008 11:43 pm

LCD, MIDI In/Out, Controls:
lcd_midi_controls_kicad_small.png

Schematic:
lcd midi controls-sch.pdf
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Re: Latest MegaDrum32 schematics. 32 inputs.

Postby dmitri » Thu Jul 17, 2008 11:45 pm

Programming cables. ISP for Atmega, ICSP for PIC18F2550:
programming_cables_kicad_small.png

Schematic:
programming cables-sch.pdf
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Re: Latest MegaDrum32 schematics. 32 inputs.

Postby elrules » Thu Jul 17, 2008 11:55 pm

in the atmega programming cable, it shows four 220 ohm resistors. I built it with one 330 resistor and three 220. Does it matter?
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Re: Latest MegaDrum32 schematics. 32 inputs.

Postby dmitri » Thu Jul 17, 2008 11:58 pm

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.
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Re: Latest MegaDrum32 schematics. 32 inputs.

Postby 6degrees » Mon Jul 21, 2008 2:57 pm

Hi Dmitri,

Thanks for all the hard work. These look great :D

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.
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Re: Latest MegaDrum32 schematics. 32 inputs.

Postby dmitri » Mon Jul 21, 2008 3:23 pm

6degrees wrote:Hi Dmitri,

Thanks for all the hard work. These look great :D

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.
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