On Apr 21, 11:40*pm, JIMMIE wrote:
On Apr 21, 6:07*pm, Joerg
wrote:





Bruce W. Ellis wrote:
On Wed, 8 Apr 2009 06:51:53 -0700 (PDT), Tim Shoppa
wrote:

On Apr 3, 10:34 am, JIMMIE wrote:
I have a Systron Donner frequency counter that uses Nixie tubes. The
counter works fine but I am forever replacing the Nixie drivers
74141s. I started to use it this AM an one was out. Is there a
replacement for the 74141, I couldnt find one, or is there a circuit I
could build on a DIP header to replace them. I could probably design
one but I wanted something tried an tested as I dont want to put my
counter board at more risk than I have to.
Domestic 74141's are hard to find these days but on E-bay the Russian
equivalent is very common.

Yes, you could build just about anything with a one-of-ten decoder and
some current-sink drivers to do the same.

If the goal isn't nixie tubes but is a working frequency counter, you
could probably put the counter up on E-bay for somebody who wants
nixie tubes, and use the money to buy several superior frequency
counters.

Tim N3QE

Just remember to cut down on the voltage and current to the nixie
tubes and the 141s will last forever...

One risk with such chips is that a nixie element occasionally reaches
strike voltage while the respective driver output is off. Or doesn't
extinguish right away when turned off. Then the dissipation in the 55V
zeners inside might be too much to stomach for the little chip.
According to the datasheet those things aren't really high voltage switches.

--
73, Joerg- Hide quoted text -

- Show quoted text -

The current limiting resistor going to the tubes is 39K. Im going to
increase that to 47K and see what happens. After putting in new chips
it may be months to a year before I see another problem with it. I
wish I knew what I was up against if I had a schematic, knew what the
voltages were supposed to be it would help greatly. I bought one a
surplus from where I work and from what I heard of its history it had
ths problem for along time. The second one I got ws at a hamfest and
it too seems to have the same problem. Could it be bad nixie tubes?

Jimmie- Hide quoted text -

- Show quoted text -

nixies are a burroughs 57505s and some other not readable type.
Ican make out the word "electronics" and the number "7341"
Interestingly these are the ones I dont have a problem with. Maybe I
have found my problem. Now to find a solution. Where can I find these
nxies?

Jimmie

JIMMIE wrote:
On Apr 21, 6:07 pm, Joerg
wrote:
Bruce W. Ellis wrote:
On Wed, 8 Apr 2009 06:51:53 -0700 (PDT), Tim Shoppa
wrote:
On Apr 3, 10:34 am, JIMMIE wrote:
I have a Systron Donner frequency counter that uses Nixie tubes. The
counter works fine but I am forever replacing the Nixie drivers
74141s. I started to use it this AM an one was out. Is there a
replacement for the 74141, I couldnt find one, or is there a circuit I
could build on a DIP header to replace them. I could probably design
one but I wanted something tried an tested as I dont want to put my
counter board at more risk than I have to.
Domestic 74141's are hard to find these days but on E-bay the Russian
equivalent is very common.
Yes, you could build just about anything with a one-of-ten decoder and
some current-sink drivers to do the same.
If the goal isn't nixie tubes but is a working frequency counter, you
could probably put the counter up on E-bay for somebody who wants
nixie tubes, and use the money to buy several superior frequency
counters.
Tim N3QE
Just remember to cut down on the voltage and current to the nixie
tubes and the 141s will last forever...
One risk with such chips is that a nixie element occasionally reaches
strike voltage while the respective driver output is off. Or doesn't
extinguish right away when turned off. Then the dissipation in the 55V
zeners inside might be too much to stomach for the little chip.
According to the datasheet those things aren't really high voltage switches.

--
73, Joerg- Hide quoted text -

- Show quoted text -

The current limiting resistor going to the tubes is 39K. Im going to
increase that to 47K and see what happens. After putting in new chips
it may be months to a year before I see another problem with it. I
wish I knew what I was up against if I had a schematic, knew what the
voltages were supposed to be it would help greatly. I bought one a
surplus from where I work and from what I heard of its history it had
ths problem for along time. The second one I got ws at a hamfest and
it too seems to have the same problem. Could it be bad nixie tubes?


Unlikely, when nixies go bad they become dim, then at some point
elements fail to strike at all. It's just that the 210V you mentioned in
another post sounds unusually high. Leaves a whopping 150V between that
and the 55-60V zener in the output of the 74141. My nixies would light
at that voltage. So if you'd have one that occasionally lit or stayed
lit and drew, say, 3ma then that results in 150mW dissipation in a very
tiny area of the chip ... phsssst ... phut ... gone. When pulling down
to near GND the chips can sink that current forever but not if 60V are
dropped.

But all this is speculation because we both don't know what kind of
nixies are in there and what the voltage was designed to be.

--
73, Joerg