This is a question that gets asked & answered on this list occasionally.
I think that the simplest/easiest answer is to use an array of high
voltage drivers on a BCD->Decimal IC. Turns into a ton of transistors if
you are not multiplexing, though. Mike Moorrees has some much more
elegant and interesting ideas in old posts on this subject. Also,
Supertex has a whole line of modern HV driver chips, some members of the
list have spent time looking into their suitability.
One nice thing to remember is that the extinguishing voltage on a nixie
is usually less than 50v (hence the zeners in the 74141). Once the nixie
is sunk by ~50v, the nixie turns off - so the driver IC doesn't have to
actually since 180v.
-Adam
On 11/23/2011 12:27 PM, chuck richards wrote:
It's a clock that I designed from scratch.
Basically, it was an exercise in using (6) 74LS160
synchronous counters. It gets the HHMM set via a bank
of (4) thumbwheel switches, and the SS gets zeroed out
and clock stopped via another spring-return toggle switch.
It worked so well that I later decided to make it into a
low current version in order to be as easy on the backup
battery as possible. So, I used all HC and HCT parts.
I used 7441 drivers because that is what I have around here.
I am not aware that any low-current versions of those
drivers were ever manufactured.
Indeed, *is* there any modern low-current bcd-to-decimal
high voltage ic that provides a one-package 16 pin DIP
solution to this requirement? Is there? Please let me
know if there is.
I am now making up another similar clock, but using 8422 tubes
instead of 6844A kind. Just thought if I could power down
the 7441/74141 ics when running on backup battery, that would
save the bulk of about 60 mA.
What low current drivers would you suggest?
Thanks again for all of your help!
You guys are a great bunch! -Chuck
---- Original Message ----
From: a...@jacobs.us
To: neonixie-l@googlegroups.com
Subject: RE: [POSSIBLE SPAM] Re: [neonixie-l] Yet more 7441, 74141
questions
Date: Mon, 21 Nov 2011 13:03:23 -0800
Is this a clock that was already built and you have been modifying
for
lower current use? or is this a clock that you designed from the
ground-up for low current? If it is the latter, I can't help
wondering
why there are 74141's in there at _all_. :)
-Adam
On 11/21/2011 10:03 AM, chuck richards wrote:
In an effort to build a low-current nixie clock,
I tried using all 74HC parts. That works great,
but there are still the (6) 7441, or 74141 TTL drivers.
How about this idea? When the clock is running on
the backup battery with no line power, what if 5 volts
Vcc were to be removed from the 7441/74141 drivers?
That way, the clock itself would keep time, and the current
draw on the battery would be kept as low as possible since
only the CMOS ics would be running.
Question: If the ground is kept on the 7441/74141 ics
and the Vcc lead is disconnected, will that cause any
problems for the 74HC160 counters that have their bcd outputs
feeding the 7441/74141 bcd inputs?
In other words, I am concerned about the possibility of
the 7441/74141 having some path that would try to
draw excessive current from the inputs when Vcc is
disconnected.
Is this a good idea to try, or is it a recipe for
trashing some HC160 counters?
Thanks. Chuck
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