[time-nuts] Re: Vernier interpolation

[Tom Verbeure]

On Tue, Jul 15, 2025 at 10:24 AM Mark Hughes via time-nuts <
time-nuts at lists.febo.com> wrote:

> Dont give up on it'
>

Definitely not! :-)


> In some designs these can easily be removed or just change the mains
> input socket if they are integrated into the socket.


>   HP instruments often have a complex mains socket with configurable
> outputs to the transformer taps for different input voltages. The casing
> can be opened with care (desoldering the screening) and the caps can
> then be removed
>

Yes, the mains sockets are usually from Comcor. I haven't checked on the
5370A yet, but I replaced one on my HP 8656A with a new one that's form
factor compatible but the contacts are in the back instead of in a cut-out,
so there's much less room for the wire. On the 8656A, I solved that by
removing all the multi-main voltage options and just hard-wiring the
transformer for 120V.


> The instrument will probably be unaffected  by the fault as the
> capacitors fail open cct
>

Good! I was hoping that this would be the case.


> The lingering smell will go away fast once they are removed.
>

2 days later, and it's lingering still in my throat. But it has happened
before...

Tom


>
>
> On 14/07/2025 19:23, Tom Verbeure via time-nuts wrote:
> > I bought myself an HP 5370A yesterday at the electronics flea market.
> Smoke
> > came out of it after plugging it in (which means I bought myself a good
> > amount of entertainment for just $40), but it made me study the dual
> > Vernier method of interpolation.
> >
> > I understand how it works, but I've been wondering if this is a technique
> > that continues to be used or has the availability of fast and
> > high-precision ADCs resulted in it being replaced by the voltage slope
> > interpolation method that's used by the SR620?
> >
> > According to the August 1978 edition of HP Journal, the 5370A is using a
> > custom hybrid with 5GHz transistors. I'm wondering if anyone has ever
> tried
> > making their own TI counter using the Vernier method? (TBH, I don't think
> > I've ever seen anyone build their own TI counter using slope
> interpolation,
> > but at least high precision ADCs are available on Digikey...)
> >
> > Tom
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