jeff@hpspdra.HP.COM (Jeff Gibson) (05/04/90)
Does anybody out there in netland have an angle on a homebuilt MIDI interface? I'm looking for an article or a schematic for building my own (I'm cheap). Is such a thing even possible? I just want to hook up my MIDI Casio keyboard to my Mac+ and use some of the public domain software that's available for playing around. I don't want to spend $300. Thanks Jeff Gibson HP-SPO jeff@hpspd@hplabs
jeff@hpspdra.HP.COM (Jeff Gibson) (05/04/90)
I put down the wrong email address, it should be; jeff@hpspdra@hplabs Sorry!
jwwalker@usceast.UUCP (Jim Walker) (05/04/90)
In article <21480001@hpspdra.HP.COM> jeff@hpspdra.HP.COM (Jeff Gibson) writes: [stuff deleted] | I just want to hook up my MIDI Casio | keyboard to my Mac+ and use some of the public domain software that's | available for playing around. I don't want to spend $300. Where did the figure of $300 come from? I just bought an Apple MIDI interface from MacConnection for $84 plus shipping. -- Jim Walker jwwalker@usceast.cs.scarolina.edu 76367.2271@compuserve.com
barry@network.ucsd.edu (Barry Brown) (05/04/90)
In article <21480001@hpspdra.HP.COM> jeff@hpspdra.HP.COM (Jeff Gibson) writes: > >Does anybody out there in netland have an angle on a homebuilt MIDI >interface? I'm looking for an article or a schematic for building my >own (I'm cheap). The following was posted to UseNet some time ago. Don't flame me if it doesn't work. From: henges@ingr.com. (John Hengesbach) Newsgroups: comp.sys.mac,rec.music.synth Subject: Re: DIY MIDI interface? Keywords: MIDI Message-ID: <3318@ingr.com.> Date: 30 Dec 88 16:05:21 GMT References: <817@ttrdf.UUCP> Reply-To: henges@ingr.UUCP (John Hengesbach) Organization: Intergraph Corp. Huntsville, Al Lines: 99 In article <817@ttrdf.UUCP> fjo@ttrdf.UUCP (Frank Owen ) writes: > > Has anyone figured out how to kludge up a Do-It-Yourself MIDI interface >for the Macintosh? It seems that the one Apple sells has practically no A reply... MINIMAL MAC--MIDI INTERFACE =========================== Well, here it is all you MIDI fans. THE ultimate in simplicity!! This is a simple schematic for a serial to MIDI converter. There are two functions performed here. One is the conversion from current loop to RS-422. The second function is supplying the 1 MHz signal for the serial chip to sync up with the 31.5K baud rate of MIDI. >>>>>>> DATA FLOW >>> (MAC TO MIDI INSTRUMENT) >>>>>>>>> +-------+ +------+ To MAC 4 10|26LS32 | |7407 | Serial >------+ |11 1| |2 +------+ 5 Port 5 9| +-----+ +-----+R=220 +-----< \ DB9 pin >------- | | | +------+ \ (5 pin DIN socket) Numbers | | | | | MIDI OUT +-------+ +------+ / (to instrument) +------+ +------+ 4 / +5 volts -+R=390 +--+ +5 volts -+R=220 +-----< +------+ | +------+ +-------+ | +------+1 +------+ 4 8 6|26LS31 | | |MCT2 +-----+R=220 +-----< \ >------+ |11| 5| | +------+ \ (5 pin DIN socket) 9 5| +--+--+ | | MIDI IN >------- | 4| |2 5 / (from instrument) | | +-+ +------------------< / +-------+ | +------+ | v Ground <<<<<<<<<<<<< DATA FLOW << (MIDI INSTRUMENT TO MAC ) <<< +-------+ +------+ 7 10|26LS31 | |1 MHZ | >------+ |9 8| OSC | 3 11| +-----+ | >------- | | | | | + | +-------+ +------+ Power connections: GROUND +5 ----- -- 7407 7 14 26LS31 8,12 4,16 26LS32 8,12 4,16 OSCILLATOR 7 14 Notes: The optical isolator MCT-2 above can probably be any relatively fast optical coupler. Note that the 390 ohm resistormay need to be adjusted to make sure the output does not saturate. Using a scope while feeding a MIDI signal in should show you whether the signal looks clean. The diagram has been drawn to show MAC signals on the left and MIDI signals on the right. There have also been allowances made for the fact that 80 column ascii displays are not **exactly** graphics terminals. Also note that the MAC pin numbers are for the DB9 connector **NOT** the 8 pin mini-DIN connector!! The age old question of where to get power for this always remains. On the pre-MAC-PLUSs, there was power available from the serial port connector. I solved this problem by finding a 7 VDC AC adapter at a parts store and using a 5 volt voltage regulator IC to bring it down to 5 volts. This is left as an exercise for the student..... The 26LS31 and 26LS32 are the same type of chips which are used in the MAC for RS-42? conversion. I got them from a store in Santa Clara California (Anchor Electronics (408) 727-3693). They also have 1 Mhz Oscillators as well. I have built several variations of this over the last two years and have had good success using a variety of music software with them. John Hengesbach (205)772-1669 uunet!ingr!henges Intergraph Corporation Huntsville, AL 35807 -- _____ Barry Brown _|__ | | | / ---- / \ \ /" __ barry@network.ucsd.edu | | | | / | -+- ----- / | bebrown@ucsd.bitnet / _| | |/ / ------ / __/ __|_ ...!ucsd!network!barry
paulr@syma.sussex.ac.uk (Paul T Russell) (05/04/90)
From article <21480001@hpspdra.HP.COM>, by jeff@hpspdra.HP.COM (Jeff Gibson): > > Does anybody out there in netland have an angle on a homebuilt MIDI > interface? I'm looking for an article or a schematic for building my > own (I'm cheap). > MacTutor published a design a few years ago (late 85 I think). I built one of these and it works well with all the MIDI packages I've tried it with. Check out the 'Best of' volumes of MacTutor in your bookshop to find the one with the design in (probably volume II). The only snag is that it's not self-powered like the Apple MIDI interface. //Paul -- Paul Russell, Department of Experimental Psychology University of Sussex, Falmer, Brighton BN1 9QG, England Janet: paulr@uk.ac.sussex.syma Nsfnet: paulr@syma.sussex.ac.uk Bitnet: paulr%sussex.syma@ukacrl.bitnet Usenet: ...ukc!syma!paulr
nick@lfcs.ed.ac.uk (Nick Rothwell) (05/04/90)
In article <21480001@hpspdra.HP.COM>, jeff@hpspdra (Jeff Gibson) writes: >Does anybody out there in netland have an angle on a homebuilt MIDI >interface? I'm looking for an article or a schematic for building my >own (I'm cheap). This seems to come up every couple of months or so... Yes, I built my own MIDI interface (though I now use a MIDI Time Piece for most things). I don't blame you for wanting to build one; the cost of the actual components is around $10. Give me a shout if you want the details. >Jeff Gibson Nick. -- Nick Rothwell, Laboratory for Foundations of Computer Science, Edinburgh. nick@lfcs.ed.ac.uk <Atlantic Ocean>!mcsun!ukc!lfcs!nick ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ Ich weiss jetzt was kein Engel weiss
henges@ingr.com (John Hengesbach) (05/07/90)
Jeff (and others who are interested),
The previous posting on the schematic is what I tried to send you
but seem to have had a bum mail address. The only addition I would like to
add is the mapping for the 8pin mini-DIN connectors.
The 8 Pin to 9 Pin comparison:
9 pin 8 Pin
----- -----
4 -------------> 6
5 -------------> 3
8 -------------> 8
9 -------------> 5
7 -------------> 2
3 --+----------> 4
|
Gnd --+-->Gnd
Vcc ----->+5
Don't forget the connection from ground to pin 3 (4 on the 8 pin)
If you do you may have trouble with receiving data from the synth to the
mac.
--
John Hengesbach
..!uunet!ingr!henges Intergraph
henges@ingr.com Huntsville, Alabama 35894-0001
(205)730-2020