In a scope clock it is probably not necessary to regulate the H.V. In a
'calibrated, laboratory type of oscilloscope', (you can think Tektronix,
and others here) it becomes mandatory that the H.V. is regulated, since
the vertical and horizontal deflection factors will be affected by
wandering H.V. accelerating potentials. The higher the accelerating
potential, the more difficult it becomes to deflect the beam in both the
X and Y axes.
Ira.
On 10/28/2025 6:09 AM, TomJ wrote:
Yet one more topic I neglected to address - voltage regulation.
Probably most critical for the deflection circuits. The majority of
examples I find on the web based on simple tube transformer based
supplies don't appear to include any kind of regulation (I'd guess
switched type supplies are regulated). But many of the examples of
basic oscilloscope type gear implement zeners for the approx +300VDC
anode / deflection supply.
On Tue, Oct 28, 2025 at 6:15 AM TomJ <[email protected]> wrote:
Forgot to mention - if anyone else is considering a crt clock
project, brand new Chinese 3RP1A tubes are available from US
sellers on eBay (3 for $85 shipped). But they are listed with the
letter "I" instead of the numeral "1" - the eBay search doesn't
pick up on that, so they are easily overlooked. I think these are
the same ones that Sphere used to sell.
On Tue, Oct 28, 2025 at 6:07 AM TomJ <[email protected]> wrote:
On Mon, Oct 27, 2025 at 4:31 PM Mac Doktor
<[email protected]> wrote:
Note that over at the GeigerCounters group talking about
building negative HV power supplies can get you banned. A
couple of people found that out the hard way after having
been warned. The -900V supplies in Geiger counters are
grandfathered in, of course, and the currents are very low.
Certainly, the voltages involved are no joke and can be
lethal. CRT voltages typically are very low current as well,
but I suspect still very dangerous. Though it seems a bit
nanny-state' to ban legitimate scientific discussions - you
can just as easily discover mortality working on your car or a
home appliance.
In any event, I also received a very informative email from
the gentleman at Sgitheach... My understanding is that the
crt tube doesn't really care - it comes down how you want to
design your circuit. Having the high potential at the cathode
makes the deflection circuit easier to implement because the
voltages are lower. BUT, if you desire to incorporate some
kind of intensity modulation or Z axis, you now have to manage
that end with high voltages. The end result from a
performance perspective will be the same.
Thanks for the insight!
--
You received this message because you are subscribed to the Google
Groups "neonixie-l" group.
To unsubscribe from this group and stop receiving emails from it, send
an email to [email protected].
To view this discussion, visit
https://groups.google.com/d/msgid/neonixie-l/CAArLthdWyGPOcwfqSukypXgCHOr2e3mBGwqTkK9w4ZXTN4ENtw%40mail.gmail.com
<https://groups.google.com/d/msgid/neonixie-l/CAArLthdWyGPOcwfqSukypXgCHOr2e3mBGwqTkK9w4ZXTN4ENtw%40mail.gmail.com?utm_medium=email&utm_source=footer>.
--
You received this message because you are subscribed to the Google Groups
"neonixie-l" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
To view this discussion, visit
https://groups.google.com/d/msgid/neonixie-l/04b7887f-6724-4965-881c-e48dda20d70b%40HUGHES.NET.
