From Newsgroup: sci.electronics.repair

I'm scrapping a homemade control circuit that appears to have been
intended as a turns counter for a coil winding setup on a lathe.

The circuit has a magnetic sensor, a bunch of hand-wired logic and
a set of nixie tubes. The only power supply recognizable is clearly
five volts. I don't see any hint of a higher-voltage supply to run
the tubes, which I thought would need close to 100 volts to drive
the gas dischrage elements.

The display tubes are labeled "RCA NUMITRON" and the logic date
codes seem to range widely, from 73xx to 0001 (not sure how the
codes jumped the Y2K gap).

Am I missing a HV power supply? The circuit is mechanically rather
a mess, so it seems unwise to just plug it in. It isn't useful to me
but I'd rather not wantonly destroy it. Each tube appears to have a
single driver IC, RCA2501E with no obvious date code. The tubes and
drivers sit on a production grade circuit board with an edge connector, probably salvaged out of something much older.

It's just a puzzle I'd like to understand.

Thanks for reading,

bob prohaska






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From Newsgroup: sci.electronics.repair

El 14/05/2026 a las 17:43, bp@www.zefox.net escribi||:

I'm scrapping a homemade control circuit that appears to have been
intended as a turns counter for a coil winding setup on a lathe.

The circuit has a magnetic sensor, a bunch of hand-wired logic and
a set of nixie tubes. The only power supply recognizable is clearly
five volts. I don't see any hint of a higher-voltage supply to run
the tubes, which I thought would need close to 100 volts to drive
the gas dischrage elements.

The display tubes are labeled "RCA NUMITRON" and the logic date
codes seem to range widely, from 73xx to 0001 (not sure how the
codes jumped the Y2K gap).

Am I missing a HV power supply? The circuit is mechanically rather
a mess, so it seems unwise to just plug it in. It isn't useful to me
but I'd rather not wantonly destroy it. Each tube appears to have a
single driver IC, RCA2501E with no obvious date code. The tubes and
drivers sit on a production grade circuit board with an edge connector, probably salvaged out of something much older.

It's just a puzzle I'd like to understand.

Thanks for reading,

bob prohaska

Numitrons are not Nixies, they are just 5 V incandescent filaments
requiring about 20 mA per filament.
--
Saludos
Miguel Gimenez

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From Newsgroup: sci.electronics.repair

On Thu, 14 May 2026 15:43:28 -0000 (UTC), bp@www.zefox.net wrote:

I'm scrapping a homemade control circuit that appears to have been
intended as a turns counter for a coil winding setup on a lathe.

The circuit has a magnetic sensor, a bunch of hand-wired logic and
a set of nixie tubes. The only power supply recognizable is clearly
five volts. I don't see any hint of a higher-voltage supply to run
the tubes, which I thought would need close to 100 volts to drive
the gas dischrage elements.

The display tubes are labeled "RCA NUMITRON" and the logic date
codes seem to range widely, from 73xx to 0001 (not sure how the
codes jumped the Y2K gap).

Am I missing a HV power supply? The circuit is mechanically rather
a mess, so it seems unwise to just plug it in. It isn't useful to me
but I'd rather not wantonly destroy it. Each tube appears to have a
single driver IC, RCA2501E with no obvious date code. The tubes and
drivers sit on a production grade circuit board with an edge connector, >probably salvaged out of something much older.

It's just a puzzle I'd like to understand.

Thanks for reading,

bob prohaska

They're not Nixie tubes, which are basically neon lamps. Numitron
have low voltage filaments, as in incandescent lighting. However,
since you didn't provide a model number for the Numitron tube (DR2000,
DR2100 and DR2200), I'm not quite sure that there are no additional
numbers. There are quite a few variations: <https://www.google.com/search?udm=2&q=numitron>

Start with the RCA Numitron data sheet: <https://www.tube-tester.com/sites/nixie/dat_arch/Numitron_RCA_01.pdf> <https://www.r-type.org/pdfs/dr2000.pdf>
The segment operating voltage is 3.5 to 5.0 VDC. I suggest you start
at 3.5 VDC and increase the segment voltage until it looks acceptable.
Starting at 5.0 VDC and going down in voltage might be a really bad
idea.
--
Jeff Liebermann jeffl@cruzio.com
PO Box 272 http://www.LearnByDestroying.com
Ben Lomond CA 95005-0272 AE6KS 831-336-2558

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From Newsgroup: sci.electronics.repair

bp@www.zefox.net wrote:

I'm scrapping a homemade control circuit that appears to have been
intended as a turns counter for a coil winding setup on a lathe.

The circuit has a magnetic sensor, a bunch of hand-wired logic and
a set of nixie tubes. The only power supply recognizable is clearly
five volts. I don't see any hint of a higher-voltage supply to run
the tubes, which I thought would need close to 100 volts to drive
the gas dischrage elements.

The display tubes are labeled "RCA NUMITRON" and the logic date
codes seem to range widely, from 73xx to 0001 (not sure how the
codes jumped the Y2K gap).

Am I missing a HV power supply? The circuit is mechanically rather
a mess, so it seems unwise to just plug it in. It isn't useful to me
but I'd rather not wantonly destroy it. Each tube appears to have a
single driver IC, RCA2501E with no obvious date code. The tubes and
drivers sit on a production grade circuit board with an edge connector, probably salvaged out of something much older.

It's just a puzzle I'd like to understand.

Ahh, so I misunderstood entirely.....

I'd seen incandscent numerical displays (long ago) but they had
a form that made the individual filaments clearly visible. The
numitrons shared a nixie form factor and I misassocidated the
form with the function.

My bad, thanks for sorting my ideas out!

bob prohaska

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