Sure, a zener will also work. It’s just that most junkboxes have so
few high volatge zeners in them ;-)
From: Ron Schuster
Sent: Monday, September 10, 2012 3:57 PM
To: neonixie-l@googlegroups.com
Subject: Re: [neonixie-l] NE-2 lamps not fully blanking
Great explanation. Thanks! So then I could actually just use a zener in
place of that resistor/diode network, right?
On Saturday, September 8, 2012 3:25:41 AM UTC-4, Frank Bemelman wrote:
Hi Ron,
Multiplexing was also often seen with LED displays (7 segment) and that
worked
very well because the segments are diodes. No currents that flow in
unexpected
ways.
Nixieclocks of the last decade also often use multiplexing. The ‘segments’
don’t behave
like diodes at all. Many unexpected current paths exist, depending on which
anodes are
on, which cathodes are off. Be aware that identical digits of different
tubes are connected
in series, because the cathodes of these identical digits are all wired
together. Disconnecting
a cathode junction sets all these cathodes floating. There is always 1
active anode. From
that active anode it is not difficult to find two digits in series, which
leads you to another
(turned off) anode, but that tube has at least one digit connected to
ground. That is not a very
good climate to ensure digits will turn off rapidly. This is the situation
if single transistors
are used as switching element. A 74141 has clamping zeners, and solves this
problem by
preventing the cathodes going too high.
You could also lower the HV. Below 135 volt you will have no ghosting.
If you add the voltage divider + diode, the cathodes (of your little neons)
are
not allowed to go higher than half HV. They are still in series between
anode
drivers, but not enough voltage left over to get ghosting issues.
Frank
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