Joerg wrote:
JIMMIE wrote:
On Apr 8, 9:51 am, 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

I forgot that the 74141 was also a decoder chip. I was thinking it was
just a driver. That complicates things a bit.
As far as the quality of the counter goes it works just fine and I
still have a few 74141s though my supply is getting low. I may try
some of the Russian chips.


If this keeps going on and becomes a money pit without a bottom there is
still the unthinkable: Hack the counter and put 7-segment LED displays
in it. Ok, all that nice Nixie-ambience will be lost but you can apply
those $7-8 per 74141 towards a more worthy cause, like a nice six-pack
of fine porter or pale ale :-)

To maintain somewhat of a vintage look: For a brief time period there
were 7-segment displays with small filaments in there. But could be
tough to find in surplus store and usually you have to buy the equipment
around them along with the display. Another nice option (if there is
enough space depth-wise) were displays with individual lamps and number
lenses. Those look really cool.

Also helpful could be to use a DSO and scope out what happens when the
counter gets turned on and off, and when the numbers are changing
wildly. Maybe some electrolytic cap has dried out and an overvoltage
spike shows up only the Nixie supply rail, occasionally frying a driver.
Ground contacts in the driver board area are also worth to be checked out.

Use the 74141 (or a 7441 I think is the lv version of the 1 out of 10
decoder) to drive HV NPN transistors. The 2n5400/5401 pnp and
2n5550/2n5551 npn are dirt cheap 120/150 volt transistors that could be
used.