Re: [neonixie-l] Rare Nimo Tubes

[Dylan Distasio]

Hi John-

I ended up grabbing one of these cheap fly swatters to test with.  Any idea
of the current these put out?

Thanks,
Dylan

On Aug 7, 2016 12:25 PM, "John Rehwinkel"  wrote:

> > I took the bait and picked up 4 of these to add to my future projects
> pile.  That said, I've never experimented with voltages beyond the dekatron
> range.  I don't know that I'm interested at this point in building my own
> kV PSU (although I would be eventually).  Can anyone recommend a relatively
> inexpensive off the shelf PSU to drive these with?
>
> I like using a CCFL supply with a voltage doubler.  Since only a tiny
> amount of current is required, you can also get away with a lower voltage
> supply (like a Tayloredge) and quite a few stages of multiplication.
> Another cheap and common source is those handheld electric flyswatters
> (which will give around 2kV from a pair of AA cells).  Negative ion
> generators are cheaply available as surplus, and can also furnish several
> kilovolts easily.  Copiers and laser printers can be a source (their corona
> wires use high voltage), or ozone generators, CRT and plasma TVs, and
> electrostatic dust precipitators.
>
> >   According to the datasheet, I should be looking for 2.5kV on the
> anode, with 1.1V on the filament.  I'm not sure exactly how to drive the
> grid.
>
> There are ten grids, one for each digit.  You can actually drive them
> directly with CMOS logic, if the filament voltage is appropriate, they only
> take a few volts.  You drive one a few volts positive (relative to the
> cathode) to light that digit, and drive the rest of them a few volts
> negative (also relative to the cathode: in CRTs, all voltages are measured
> relative to the cathode).  A common lashup is like in the data sheet, where
> pulldown resistors keep the grids held low, and transistors are used to
> pull one positive at a time to light the digit wanted.
>
> >   Does the grid consist of the cathodes?
>
> The filament is actually the cathode.  The grids are the apertures for
> each digit.  You can drive the filament using an ordinary transformer, with
> dropping resistors or capacitors calculated to deliver the rated amount of
> power.  You can even drive it directly from a pair of 5V inverters operated
> out of phase, along with appropriate dropping resistors or capacitors.  In
> this instance, capacitors are preferred, so you can bias the filament to
> the DC voltage you want to make the grids voltages easy to work with.  If
> you're working with 10V CMOS, and bias the filament to +6V, you can simply
> ground the grids that are off, and connect the one you want to turn on to
> +10V.  This will give the grids the -6V/+4V swing (relative to the cathode)
> that they're supposed to see.
>
> >   Apologies, but I have zero CRT experience at this point, and any
> pointers would be appreciated.  I'd like to at least be able to test these
> when they come in.
>
> The easiest test is a continuity test to make sure the filament isn't
> broken.  However, I'm guessing you want to see one lit.  Go find one of
> those electric flyswatters for the anode voltage (they're a few dollars),
> and be careful, you don't want to touch high voltage, and have your reflex
> throw your tube across the room!
>
> - John
>
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[neonixie-l] Re: Valvo datasheet "Valvo Brief" from 26.04.1970 with DDM14 circuit - does anyone here have this?

[Nick]

As Valvo were part of Philips, I dropped a line to Ronald Dekker, who, as 
we know, a) has access to the Philips archives, and b) has a deep interest 
in this sort of stuff - maybe he'll be able to help?

Nick

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