Neon Lamp Matrix

[Tom Harris]

Can someone please help me out, I remember an article from some scanned book from the 60s where a set of neon lamps were connected in a matrix with clever biasing and pulses on the row & column could toggle an individual lamp. I thought it was the GE glow lamp manual but it seems not. 

[gregebert]

If it was pulsed-DC, then it probably was simple multiplexing.

I have thought about doing it with AC, which makes the driver more complex, but it will make the bulbs last longer since both electrodes will be illuminated (alternately, of course). Not sinusoidal AC, but square-waves. If you do the math, a typical neon bulb is "on" for about 2/3 of an AC cycle (on at 90V, off at 60V) so that would be my starting point for multiplexing. I was thinking a 7 x 9 matrix, using 2:1 multiplexing. It's more driving circuitry but it might be possible with an HV-series device that can drive high and low.

[Tidak Ada]

There was ever a Mullard ZM1251. A 5×7 neon dot matrix at the size of a stamp.

 

eric

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[Tom Harris]

Thanks for the ideas but it was definitely static with the pulses just used to turn the lamps on or off. After that they would keep their state indefinitely.

Tom Harris <celep...@gmail.com>

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[Tom Harris]

Wow each lamp was individually pinned out. How did they drive these? Big diode matrix?

Tom Harris <celep...@gmail.com>

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[Jon Jackson]

is this a ZM1251 or ZM1215 ??  You have conflicting info...

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[Tidak Ada]

Oops, a typo.It is ZM1215 of course as the file name says.
eric

Verstuurd vanaf mijn iPhone

Op 5 mei 2021 om 22:36 heeft Jon Jackson <jond...@gmail.com> het volgende geschreven:



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[Jon Jackson]

Copy that...

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[gregebert]

So if the display was static, using only pulses to turn bulbs on or off, then it was most likely all bulbs were resistively tied to a sustaining voltage, say 70 volts.

If individual rows were sequentially pulsed higher, say +85V while columns were pulsed slightly negative, then those targeted bulbs would turn on. It would be very tricky because the ionization and sustaining voltages will change over time and vary across manufacturing lots.

[Tom Harris]

Gregebert you are quite correct about the probable connection and the voltage spread, it would only work within the same batch, I built a 3x3 and it was tricky as hell to get working. I'm told there were Soviet era neon lamps with a wider voltage spread that would be easier.

Maybe this guy: https://hackaday.com/2020/07/23/384-neon-bulbs-become-attractive-display/ knew about the issues!

Tom Harris <celep...@gmail.com>

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