[time-nuts] WWVB remodulator for the Spectracom 8170...

paul swed paulswedb at gmail.com
Tue Jun 18 17:51:29 EDT 2013


Thanks Attila Burts looking to separate the rcvr/remodulator.  I am fine.
Yes indeed I did look up the hc specs. I thought it was a 5v logic
actually. I knew it was not at all like the 74c series.
Regards
Paul


On Tue, Jun 18, 2013 at 5:21 PM, Attila Kinali <attila at kinali.ch> wrote:

> On Tue, 18 Jun 2013 10:52:24 -0400
> paul swed <paulswedb at gmail.com> wrote:
>
> > Interesting the HC will work all the way down to 2.2V so everything can
> be
> > run from 3 Volts.
>
> I don't have a spec sheet at hand, but are HC types speced down to 2.2V?
> I thought it was something around 3V
>
> > No idea as to the effect of the xtal oscillator maybe the 3.9 M R needs
> to
> > be changed.
>
> Probably not. the 3.9M resistor is to give the oscillator circuit
> (which is an unbuffered inverter) a DC bias. Its value is usually not
> critical.
>
> > It also appears that the HC chip may doing the lions share of current
> > consumption. Spec sheet says up to 20 Ma. Hard to believe actually.
>
> As long as it's mA not MA, it is indeed believable ;-)
> HC used quite a bit of current. Especially when toggling at high speed
> (where as high speed is to be seen relative to the 70s when these chips
> were designed).
>
> > As for driving lengths of wire over distance it needs to be a buffer
> chip.
> > 74hc244. But that seems like serious overkill it can drive 20 ma per
> port.
>
> If it's just a single signal, why not use a pair of digital mosfets like
> FDV302P/FDV303N? These can drive a big load (680mA speced, with good
> cooling)
> and are can be interfaced with 3V logic.
>
>
>
>                         Attila Kinali
> --
> The people on 4chan are like brilliant psychologists
> who also happen to be insane and gross.
>                 -- unknown
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