TurboCPU DAC/CV Option – New Parts Source?

I made an interesting discovery on the web today. There are a lot of companies making “Breakout Boards” and “SMT to DIP Adapters” but I’ve never found an assembled one for the MCP4728 DAC used in the TurboCPU’s CV/DAC option … until today!

From here:  http://www.proto-advantage.com

I just ordered one assembled breakout board (DAC chip and pins installed) as well as just a blank board with machine pins. I will test them both out. If it all works out then this is a good place to order these parts from because making the CV Option is a major bottleneck for me.

Here are the parts I ordered:


PA0027-WW-IC_T

MCP4728 Breakout Board, chip included, assembled.

http://www.proto-advantage.com/store/p/MCP4728_Breakout_Board.php?gclid=CKyByJrNk78CFZJbfgodBA4AkQ

Part Number: PA0027-MCP4728, MCP4728 Breakout Board


MCP4728 DAC breakout board, unassembled, DAC not included.

MCP4728 DAC breakout board, unassembled, DAC not included.

http://www.proto-advantage.com/store/product_info.php?products_id=2200031

Part Number: PA0027, unassembled with machine pins, ROUND.


A few things to note about this right up front. Since the beginning of 2014 I have added a second area on the TurboCPU’s MIDI board to put the DAC chip on. The original area is the tiny MSOP-10 footprint, the new area is a 10-pin DIP footprint.

MIDI board showing both DAC locations (in red)

This has allowed me to order MSOP-10 to DIP adapter boards… which makes assembly a bit easier.  To date I’ve been using adapters from

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=120750047844

and

http://www.nkcelectronics.com/msop10-to-dip-adapter-101010.html

but this new discovery from Proto-Advantage is very exciting! Now, because I’ve also been installing a 10-pin DIP socket I think the round machine pins are the better way to go as I’ve never really liked the idea of jamming square wire-wrap pins into a DIP socket.

The other alternative is for me to leave off the DIP socket and just allow you to solder the Proto-Advantage fully assembled breakout board right on the PCB. Once I get these and test them out I’ll decide which route to go.

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3 Responses to TurboCPU DAC/CV Option – New Parts Source?

  1. grantb4 says:

    I’m working on a Rev D version of this board that will remove the DAC SMD part completely and instead offer better support for the DAC daughter PCB. I will enlarge the holes to accommodate the Proto-advantage.com square pins and I’m going to run separate traces for the VCC and GND to the analog part(s). Finally I will add another 10uF cap and a 0.1uF cap near the DAC daughterboard.

  2. grantb4 says:

    As mentioned, this is the part number to order the finished board that can be installed (through-hole soldered) onto the recent versions of the TurboCPU’s MIDI board:

    http://www.proto-advantage.com/store/p/MCP4728_Breakout_Board.php?gclid=CKyByJrNk78CFZJbfgodBA4AkQ

  3. grantb4 says:

    There are a couple of other not-quite-drop-in alternatives for those that don’t mind some wiring but are loathe to do 0.5mm SMD work. Of course if you have my MIDI board then you can buy my DAC board or the one mentioned above. HOWEVER, the way postage and shipping is, these alternatives might be attractive.

    #1 Adafruit MCP4728 Breakout board: https://www.adafruit.com/product/4470

    #2 Zeflex Designs MCP4728 DAC Board: https://www.ebay.com/itm/12-Bit-Voltage-Output-DAC-with-Four-Buffered-Output-Based-On-MCP4728-Chip-/202756470253

    In both cases the easiest thing to do is wire these boards back into the 10-pin DIIP socket on the MTG MIDI board. Because these boards already have I2C pullups, it is necessary to adjust the I2C pullups on the MTG MIDI board. Locate the two 2.2kohm resistors on the MTG MIDI board and replace them with two 4.7kohm resistors (so each 2k2 becomes 4k7 instead).

    As always, refer to the information in the installation manual:
    http://musictechnologiesgroup.com/files/ProOneTurboCPU_CVInstall_v141.pdf

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