[time-nuts] minimalist sine to square

[Dana Whitlow]

Tom,

I recently built such a device using a couple of stages of a 74HC04,
with the RF input to the 1st stage AC coupled and the input biased
by a high-value (a couple of megohms) resistor feeding back from
the output of the first inverter stage to the input of that stage.  It's so
dirt simple, it's hard to beat.

I was not particularly concerned about jitter, so if you're not already
familiar enough with the circuit to know whether or not it's good
enough, it might be worth a try.  BTW, I am running at 10 MHz from
a PRS-10 Rb, and just wanted something to drive a count-down
chain. And there's always the 74AC04 if you wanted faster edges.

Dana Whitlow


On Fri, Jan 19, 2018 at 1:31 PM, Tom Van Baak <tvb at leapsecond.com> wrote:

> John's TADD-2-mini [1] uses the Wenzel sine-to-square converter. It
> performs very well but requires +10 V.
>
> I'm looking for a solution that works at 5 V (e.g., USB powered) and also
> uses fewer parts. Wenzel also mentions using a differential line receiver
> [2]. That would be an ideal single-chip 5 V solution for me but the two
> parts he mentions, MC1489 [3] and SN55182 [4], don't appear fast enough for
> a 10 MHz input.
>
> Can any of you circuit experts suggest some line receivers that would
> work? Maybe DS9637 [5]? This isn't for cesium work so it doesn't have to be
> quite as good as the TADD-2.
>
> Thanks,
> /tvb
>
> [1] http://www.tapr.org/~n8ur/T2_Mini_Manual.pdf
> [2] http://www.wenzel.com/documents/waveform.html
> [3] https://www.onsemi.com/pub/Collateral/MC1489-D.PDF
> [4] http://www.ti.com/lit/ds/slls092d/slls092d.pdf
> [5] http://www.ti.com/lit/ds/symlink/ds9637a.pdf
>
>
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