11/23 clock issue

Brent Hilpert hilpert at cs.ubc.ca
Sat Feb 7 17:56:42 CST 2015

On 2015-Feb-07, at 8:47 AM, Noel Chiappa wrote:
>> From: Tothwolf
>> Before I forget again, did you check for +5V on pin 1 (enable) when you
>> were testing your existing oscillator?
> Wow. Never thought to try that. Then again, I don't look for +5V on your
> average 74xxx when I'm debugging, either! :-) I mean, it's a trace, the
> solder on the pin looks good, that's as far as I go, usually! And there's
> nothing shown as connected to that pin on the circuit diagram.
> So I looked, and... it's at ground (or floating). The only pin that has
> anything is 14, at +5V (expected). But I looked online for some datasheets
> for similar oscillators, and some of them say 'pin 1 - N/C'. Are yours
> tri-state? (That's the enable pin on the tri-state ones.)
> I suppose even if yours are tri-state, I can still use them; a quick ohmmeter
> check shows that pin 1 isn't connected to either power or ground, so I can
> probably tie it high (via a resistor, which in addition to being normal
> practise, will prevent a major disaster in case I'm confused - a state I'm
> often in :-).

You shouldn't need to do anything regarding pin 1, (this) datasheet indicates they (the FOX F5C-2 series) have an internal pull-up R on pin 1,
so the output should be active by default.


As your fault description sounds like it could be stuck in tri-state, you could try an experiment with your existing osc. and pull pin 1 high through an R to see if it activates, on the small probability the internal fault is loss of that internal R.

I have one 13.824 unit I was going to offer but Tothwolf has lots of them, so all the better there.
They are a baud-rate generator frequency for the standard (300..9600..19200...) baud rate series as well as the 14400..57600.. series.
Could probably be found in some 90s-era modems.

If you want to be comprehensive/paranoid you could still affirm that inverter input is functioning properly on the also-small probability a fault there wrecked the oscillator output.

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