MIDI interface clock

[John Speth]

At 06:21 PM 5/7/97 +0200, you wrote:
>Hi,
>        I started building a MIDI interface, but am stuck at the moment.
>I am using a 6402 UART, and have got the input and output stuff done,
>with an opto-isolator and not gate.
>The problem seems to be with the clock.
>The circuit is something like
>
>                +---Not----+---Not----- Out
>                I          I
>                I-Resistor-I
>                I          I
>                I-Xstal----I
>                I          I
>              Capacitor  Capacitor
>                I          I
>        -------------------------   0v
>
>I am using a ceramic resonator instead of a xstal, but I can't seem to get
>much of an output.
>Should this circuit work? All the others seem to have the not gates in
series.
>Is there a similar circuit I could use using a 4001 quad nor gate, a 500MHz
>Ceramic resonator, and a few resistors and capacitors.

500MHz (!!!!!) using CMOS ?????  It'll never happen (if that's not a typo).
 A 4001 CMOS gate will not clock that high.  Maybe you mean 500KHz?
(That's ok).

I have a digital design book from college that reviews a handful of TTL and
CMOS based clock circuits stating pros and cons.  One of the cons that came
up in a few designs were "won't self start".  Maybe that's your problem.
Try a different topology.  You'll need to do some research if you don't
have other circuits to try.  Or you could always use an integrated digital
clock chip.

John Speth (johns at oei.com)
Object Engineering, Inc.
Vancouver, WA