[[S] Two DOUT Kits - new/unopened]

For Sale: Two (AV Showtech) DOUT Kits (new/unopened). $22. + $2 shipping/handling to anywhere in USA. May consider offer. Can be paid by PayPal.

[DOUT with ULN2803's (to drive Pipe Organ valves)]

The ULN2803 is plenty to drive a 50ohm magnet

Yes the ULN's will do fine, its the traces on the DOUT board from the ULN2803 output to the output header that concerns me (only when using ULN2803's) as they have to carry the load of an electo-maganet. On various pipe organ driver boards that incorporate ULN2803's, the traces and ground are beefed up.

Pipe valve example: http://www.petersonemp.com/products/pdf/Seriesii.pdf (pdf)

Thanks.

[interface to common memory card]

The good thing of some card types is that they use standard serial interface types. Parallel ATA would be possible (I´ve seen some MP3 player projects that use HDs) but uses a lot of port lines. PATA has the advantage of the old and slow compatibility modes, but for SATA you´d surely need extremely fast timings.

Anyway, except for Video or WAV streaming, I don´t see the need for hard drives anymore. In the meantime you can get 1 GB SD cards for around 20 Euros. They are small, cheap, mechanically reliable and have a simple interface - and 1 or 2 GB is sooo HUGE compared to a BankStick, so I doubt it´s really worth the effort to develop a HD interface.

some links for inspiration:

http://www.mikrocontroller.net/articles/Projekt_Mr.MIDI_-_Midi_Rekorder_mit_MMC/SD-Karte(german)

http://www.ulrichradig.de/home/index.php/avr/mmc-sd(german)

http://www.roland-riegel.de/sd-reader/

Seppoman

More SD Midi Controller links...

http://www.lehmayr.de/e_mrmidi.htm (english)

http://www.sdmidicontroller.com/self-assembly-pcb-kit/default.htm (Kit)

[DOUT with ULN2803's (to drive Pipe Organ valves)]

In using the R4 DOUT with ULN2803's as driver boards, how much load can the board support from the ULN2803's to the output headers? Typical pipe organ valve magnets range from 90 to 50 ohms. The common ground supports multiple valves on (up to eight) all on at once. Are the output traces designed to handle this?