A bit $teep for a DMM

[Mac Doktor]

What makes this DMM so valuable? There are only four tubes to yank out:

https://www.ebay.com/itm/405017664588

Terry Bowman, KA4HJH
"The Mac Doctor"

https://www.astarcloseup.com

“...the book said something astonishing, a very big thought. The stars, it said, were suns but very far away. The Sun was a star but close up.”—Carl Sagan, "The Backbone Of Night", Cosmos, 1980

[Nicholas Stock]

It's a Fluke?

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[gregebert]

The bid history shows 2 people really wanted it. It's an unusual DMM because it's 4-1/2 digits rather than the much more common 3-1/2. I understand the "tulip-fever" frenzy over functional nixie-tube equipment; I bought an HP 5245L counter from a local surplus shop a few years ago for $175. I had no interest in the tubes, and didn't have much need for a frequency counter, but because it's working and has a lot of digits, the wow-factor overwhelmed my sense of reason.

[Mac Doktor]

On Jun 12, 2024, at 6:34 PM, gregebert <greg...@hotmail.com> wrote:

The bid history shows 2 people really wanted it. It's an unusual DMM because it's 4-1/2 digits rather than the much more common 3-1/2. I understand the "tulip-fever" frenzy over functional nixie-tube equipment; I bought an HP 5245L counter from a local surplus shop a few years ago for $175. I had no interest in the tubes, and didn't have much need for a frequency counter, but because it's working and has a lot of digits, the wow-factor overwhelmed my sense of reason.On Jun 12, 2024, at 6:34 PM, gregebert <greg...@hotmail.com> wrote:

I understand the "tulip-fever" frenzy over functional nixie-tube equipment; I bought an HP 5245L counter from a local surplus shop a few years ago for $175. I had no interest in the tubes, and didn't have much need for a frequency counter, but because it's working and has a lot of digits, the wow-factor overwhelmed my sense of reason.

I have several that I paid a lot less for. Here's my nine decade counter:

The 6053 is 1GHz and has an N connector. I love desktop models.  8D

The prices on eBay for stuff like this have increased somewhat in the last couple of years but it's not exactly Tulipomania.

[cm...@zeusprune.ca]

Re: [neonixie-l] A bit $teep for a DMM

On Wed, Jun 12, 2024 at 11:57 AM Mac Doktor <themac...@gmail.com> wrote:

What makes this DMM so valuable? There are only four tubes to yank out:

 

https://www.ebay.com/itm/405017664588

 

 

It is a FLUKE, you would  only Yank the tubes to clan the pins and remove the dust from the sockets... then reassemble carefully and bow down in Veneration.

[Adrian Godwin]

I much prefer Nixies in functional equipment rather than for their own sake. And while displaying them in a clock is fine, there are other types of clock to cherish too, leading to a loss of space. And since I can build a clock myself, other functionality is attractive (admittedly I wouldn't pay $300). 

It's a pity there aren't a lot of devices other than counters and DVMs to find - I already have Philps, Racal and Avo examples. I'd like to find a nixie-based measurement system such as a Heidenheim. 

Are there any other types of instruments that were made ?

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[Paul Andrews]

Why not both? Here is my partially successful attempt to display the time on a frequency counter by generating the correct frequency that would result in the time being shown in the frequency counter. I had forgotten about this until I read this thread:

https://www.nixies.us/2018/03/25/display-the-time-on-an-old-frequency-counter/

[Adrian Godwin]

Interesting idea. 

I'd speculate that the accuracy problem where the counter failed to see some pulses is perhaps a synchronization problem. If the pulse-counting method worked by generating a variable number of pulses at 240kHz then they should always be visible to the counter as long as that's within it's range. But if the gate period of the counter didn't coincide with the gating of the pulses at the generator, you would get variable results. And there's no obvious way to make them synchronise without stop/start signals.

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[gregebert]

I'm planning a similar approach with the HP5245L, but instead I will run the counter with a 10-second gate. The gate signal is an *output* from the counter, and while the signal is active, it just acts like a regular counter. So, all I need to do is wait for gate to go active, send a stream of pulses (up to 235,959 of them), and they will display the time.

The odd thing about the 5245 is that the display is on while counting; annoying if you are measuring frequency but just what you need for a clock. After the initial count is displayed, which is pretty fast at 50Mhz (less than 5msec), the next 9+ seconds only require a single pulse to advance the seconds in most cases. When there is a rollover for the next minute, you need to send 41 pulses so that xx:x1:59 becomes xx:x:2:00 . Similar exceptions for ten-minute, hours, etc. At midnite, this trick wont work so you may as well flood the device with an erratic burst of pulses to make most of the digits roll.

Since a 50Mhz pulse-output is too fast for a cheap microcontroller, it will be done from an FPGA.

Of course I wont keep this thing running 24/7 because of the noise and wasted electricity. But at least I will get more usage out of th3 5245L.

[Adrian Godwin]

It's true most micros won't run instructions that fast, but outputting a count of pulses can often be handled by a timer peripheral at anything up to the system clock rate. Alternatively a microprogrammable peripheral such as the RP2040 PIO, Beagleboard PRUs, or the  venerable Motorola TPU.

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[Mac Doktor]

On Jun 13, 2024, at 10:04 AM, Paul Andrews <pa...@nixies.us> wrote:

Why not both? Here is my partially successful attempt to display the time on a frequency counter by generating the correct frequency that would result in the time being shown in the frequency counter. I had forgotten about this until I read this thread

Wow, I could display several time zones at once. 8D

Terry Bowman, KA4HJH
"The Mac Doctor"

https://www.astarcloseup.com

"Every kid starts out as a natural-born scientist, and then we beat it out of them. A few trickle through the system with their wonder and enthusiasm for science intact."—Carl Sagan, Psychology Today, 1996

[Adrian Godwin]

On Thu, Jun 13, 2024 at 6:17 PM Mac Doktor <themac...@gmail.com> wrote:

Wow, I could display several time zones at once. 8D

I assume because you have more frequency counters than some people might feel is strictly necessary :).

But if several time zones at once is useful to you, perhaps because of amateur radio or something, I think e-ink price labels might be a nice way to make a custom multizone clock. As any displays as you want, stuck whereever you want,  updated from a central clock.

What is needed is a way to make them self-illuminating, like any self-respecting display technology would be. I wonder if the white side of the cells fluoresce under UV ?

[Mac Doktor]

On Jun 13, 2024, at 1:34 PM, Adrian Godwin <artg...@gmail.com> wrote:

Wow, I could display several time zones at once. 8D

I assume because you have more frequency counters than some people might feel is strictly necessary :).

You got it. What I don't have enough of are the AC cords. I've been collecting those as well.

Terry Bowman, KA4HJH
"The Mac Doctor”

https://www.astarcloseup.com

“My definition of an artist is someone who’s ahead of his time and behind on his rent.”—Kinky Friedman

[Paul Andrews]

Hmmm. Maybe I need to have another look at this. Anyway I have faster processors now too.

[gregebert]

> You got it. What I don't have enough of are the AC cords. I've been collecting those as well.

Whoever came up with the standard IEC power cord deserves a Nobel prize.