midi-sync24 schematic, not the best photocopy

Luka · Joined: Jun 29, 2007 Posts: 1003 Location: Melb.

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i want to use my 606 and tb303 and hopefully this converter will do the job.
there are a few things inside it that are confusing me. first the cmos NOT gates at the start would be from a 4049 would they not? (pun intended Wink

) it looks like 4044 is written down but 4049 makes more sense to me.

also between the top line of not gates there is a 10k resistor and something else. what is that, i havent seen that symbol used before and cant read the anotation.

widdly · Posted: Tue Jul 22, 2008 7:15 pm Post subject:

Nice idea.

It looks like 4049 to me which makes sense.

The other thing is a crystal oscillator. They usually have a frequency. Very hard to read on your diagram.

Apparently this is powered from the midi port. There doesn't seem much detail on that. Is the power coming off the midi thru?

richardc64

Even enlarged the crystal marking is hard to read. Looks like something5500KHz.

Power connections are omitted for "clarity." The horizontal lines above components seemingly going nowhere are the positive supply -- most likely 5volts -- and the horizontal line below components are ground.

etaoin · Joined: Jun 30, 2005 Posts: 761 Location: Utrecht, NL

widdly · Posted: Tue Jul 22, 2008 11:56 pm Post subject:

Yeah the self powered bit is what I find intereseting. I have a few commercial boxes that are port powered and always wondered how they do it.

Is the 2k2 resistor coming of the midi in supplying the power? I would have thought you would need a capacitor as well.

Luka · Joined: Jun 29, 2007 Posts: 1003 Location: Melb.

here is the pcb layout etaoin
there was no component layout posted
it came from here
http://www.hollis.co.uk/john/circuits.html

etaoin · Joined: Jun 30, 2005 Posts: 761 Location: Utrecht, NL

Dave Kendall · Posted: Thu Jul 24, 2008 2:48 am Post subject:

Hi All.

Maybe I can help out a bit.......? I've got a *very nearly* working 6402 based MIDI to sync24 converter on the test bench using CMOS and HCMOS. Sadly, it's been mothballed there for a year or so, as it's doing more or less everything it should, *except* that there is an extra pulse on the CLOCK OUT pin whenever a START or STOP command is recieved, which throws off the timing when a divider chip is used to get 1/16 divisions and so on.

I've used different parts from what I can make out from the schematic, and mine's got Blinkenlights on it Smile

I suspect I'm not too far off at all, but have got stuck at the last hurdle....

There are some very rough schematics (well, sketches really....), and they will need re-working to take into account the latest bits that are on a breadboard. The original intention was to get the circuit fully working and donate the idea and schematics to electro-music if people were interested. Perhaps jointly we can get the best bits of the circuits and come up with a soild working design, and maybe even a PCB? My original idea was for a MIDI clock to pulse converter, with MIDI PGM change to select the divisions. The design looks like it will allow for this, although I've only had a few rough ideas so far for the PGM change decoding. This part would probably add quite a few extra logic ICs, but it's all PIC-Free for CMOS junkies! Smile

What do you all think?
Am very busy for a few days, so can't do much on it for a wee while, but am happy to share what I've got so far with EM......

cheers,
Dave

prototype.JPG

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Very early photo. About 7 ICs + a few extra bits and bobs needed to get it to work.....

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etaoin · Joined: Jun 30, 2005 Posts: 761 Location: Utrecht, NL

Where did you find your 6402?

Dave Kendall · Posted: Thu Jul 24, 2008 3:11 am Post subject:

etaoin · Joined: Jun 30, 2005 Posts: 761 Location: Utrecht, NL

Maybe I'll try to sample it. It needs to come cheap, as I already have two ADV-MIDI boards that do exactly the same (and more). I'm just intrigued by the simplicity of this one.