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Cutting edge GM counter (1953)

Posted: Fri Jun 21, 2019 7:01 am
by Richard Hull
As some here will know, I collect and restore old Geiger counters from the U-boom era (1949-1960).

I have just restored a very rare, seldom seen, Hoffman "Count master" Geiger counter/rate meter/scaler. It has sat around for 10 years.

Amazingly compact and light weight for its time, it includes an unheard of all electronic digital counter, (scaler), and mechanical timer built in.
It employs only three vacuum tubes! None of the tubes are in charge of, or involved with, the digital counter!
The four decade counter uses only NE-2 lamps, capacitors and resistors. Normally such decades of the period that used NE-2s as indicators in stacked decades demanded 4 flip flops made up of 8 vacuum tubes per decade.

GE was the prime manufacturer of the series of NE lamps and produced a thick manual on their use. It seems that due to their natural hysteresis (on-off voltage characteristics), a form of ring counter can be assembled using only 10 small NE-2 lamps per decade as both the active and indicating components.

I was stunned at this rather ingenious work-around for the period. In reading the GE manual one notes that the NE-2B lamps are used which are more stable, and even then, for best results, they should be selected by hand from a batch to match their characteristics. Hoffman took the time and effort back then.

My restoration consisted of replacing two old foil electrolytics with modern 1/10th size replacements and the HV wax filled 1600v filter capacitor.
I also replaced what was supposed to be (2) 75 volt batteries, with one of my tiny 6 volt to 120-160 volt adjustable supplies for the vacuum tube plate power. I made a few adjustments to the metering pots and it worked perfectly.

For those old farts like me who remember the HV carbon-zinc pile batteries, I never heard of or have ever seen a 75 volt battery. I clearly remember the voltages of all such batteries that were common to the period. They were 15 volt, 22.5volt, 30 volt, 45 volt, 67.5 volt and 90 volt. The highest voltage Eveready made was 540 volts. This 540 volt battery was produced exclusively for the early "Strobenar" photographic Xenon portable flash units. Any "old boy" ever see or handle a 75 volt battery?

I attach an image of the finished counter. click on it to enlarge.

Richard Hull

Re: Cutting edge GM counter (1953)

Posted: Fri Jun 21, 2019 10:17 am
by Rex Allers
Great work on bringing this primo device for the time back to life. Nice job.

The description of the NE decade counter design is amazing. I've never heard of such a thing.

I recently got an ebay x-ray monitor, circa 1975 design. It also uses a high voltage battery (300v). Not for tubes but for the detector. There was a very dead battery in it. Swollen from years of age. Quite a battle to get it out without damaging anything I was prying against.

Here's a pic of the cardboard case from the battery that I saved for reference.
Like you I replaced the 300V battery with a small switching supply for testing. I could fit something into the battery chamber, but...

The device seems to be doing some odd things and I have no schematics. For me, this project is now bumped far down my list. Too many unknowns to try to hack it.

Re: Cutting edge GM counter (1953)

Posted: Fri Jun 21, 2019 4:43 pm
by Rich Feldman
Very cool.
I used an instrument with the same kind of 10-lamps-in-column decade counters, in summer of 1974. It had been in continuous service since new. Measured elapsed time, in milliseconds, for profiling soil depth by seismic refraction.
hammer.JPG (26.18 KiB) Viewed 3685 times

Re: Cutting edge GM counter (1953)

Posted: Sat Jun 22, 2019 7:43 am
by Richard Hull
Thank you for the battery exterior image. That type of Ever Ready battery packaging design was their last gasp at the major high voltage "pile" batteries, using carbon-zinc battery technology. Your Battery is another rare bird. By the early 80's, Ever Ready killed their use of their most famous logo...The black cat leaping through the numeral 9 as their "nine lives" image so familiar on all of their batteries for a half century.

I have been trying to track down data on when Ever Ready ceased all such battery construction. Wiki notes that the Ever Ready of old is no longer. Union carbide sold off their Ever Ready battery division to Ralston Purina in 1986. I truly feel that this was the end of Every Ready pile batteries. The last 67.5V battery I bought was in the early 1990s from Batteries Plus, at that time they did have access to the 450 volt Ever Ready battery. I went back in the mid 1990's and they said Ever Ready no long produced any High voltage batteries over 30 volts and that those were in jeopardy.

Since 1986 the battery division has been resold a couple of times and is currently listed as "Energizer Holdings" and over 80% of all Ever Ready batteries are now made in China. The one single Ever Ready production facility in the U.S. making batteries is in North Carolina.

All of this was to be expected over time. Almost no portable devices today demand the use of an internal voltage exceeding 9 volts. Real power for such portable devices are limited to NiMH and Lithium batteries. If high voltages are needed in portable situations, modern switcher boost technology is used powered by high capacity low voltage cells.

Toys and cheap electronic junk items sold worldwide, still use carbon-zinc batteries. I was stunned to learn that all Ever Ready "Energizer" batteries are still carbon-zinc made in China. These are in a black wrapper. Only those Energizer batteries with the alkaline or lithium chemistry use those words on the label which is usually bright aluminum labeled. The Bunny, never imaged on the battery, has replaced the Cat.

Nuclear portable instrumentation was produced with vacuum tubes until the late 1960's. Many government and civil defense agencies had thousands of these instruments on hand and this demanded and supported the continued production via government contract of these pile batteries into the late 1980's. Some transistorized gear made as early as the late 50's still needed the HV pile batteries for the GM Geiger tube's high voltage circuit.
Total solid state independence of pile batteries really took off in the late 60's with tiny step-up transformers to obtain high voltages needed. The old tube gear used a vacuum tube based inductive boost oscillator to push the 90-115 volts pile battery up to 1,000 volts for the GM tube.

I include some images for the youngsters of what "real batteries" used to look like.
Good images of the two most popular pile batteries, 45v and 67.5v and then one of a whole gaggle o' high voltage batteries up to 90 volts.

Richard Hull

Re: Cutting edge GM counter (1953)

Posted: Sat Jun 22, 2019 2:14 pm
by Rex Allers
Richard, Great history on the HV batteries.

Another unusual thing about the 300V battery is its connection terminals.
Here's a pic of the connection assembly from inside the battery.
The battery had red and black sockets that plugged onto standard sized banana plugs in the device. The only change from when it was in the battery is that I soldered the red & black wires on it to use for a replacement supply.

The device is a Radcal mdh 1015 Radiation Monitor. From some searching, the design was around 1975 but I just looked at the device and there is marker pen writing that says, "New 4-27-88". There is a label that says it passed testing in 2008, and surprisingly, there is also a label that says the 300V battery was replaced 9/18/06. I looked at the battery cardboard and the bottom end has printing: 1205.

So it seems that battery was still being made by EveReady at least in the end of 2005. More recent than I would have expected.

The dates on the device are a bit newer than I realized too. Maybe it can be got working. One of these days.

Re: Cutting edge GM counter (1953)

Posted: Sun Jun 23, 2019 4:21 am
by Bob Reite
I remember building a "two tube radio kit" in Cub Scouts that used a 90 volt "B" battery (plate supply) A D cells for the "A" battery. (filament supply)
it had a 1U4 grid leak detector and a 3Q4 (or was it a 3V4? Same tube, different pinouts) power amplifier that could actually drive a 4 inch speaker.

Re: Cutting edge GM counter (1953)

Posted: Sun Jun 23, 2019 5:56 am
by Richard Hull
1 volt and 3 volt tubes were the tubes used in all pre-transistor portable radios taken to the beach and out door dance parties from the late 40's until the very late 50's and early sixties when affordable transistor radios replaced them. All early military GM counters used these tubes as early as 1945.
1 volt filament tubes were nothing new. They go back to the 20's into the early 40's, but all the early ones had the rather large, odd 4, 5, 6, 7 pin bases. Ultimately, all major receiving tubes in the late thirties and during WWII standardized on the large, octal base. Needless to say, the early portables of the 1920's-1930's were not very portable, but were luggable. With the advent of the 9 and 7 pin "minature" tubes during WWII, portable battery powered gear became smaller and lighter.

I looked at my last buy on the 67.5 volt, and as you can see in the pix, I bought this in 2006. So, they were still making these in 2006. I do know when I went back to Batteries Plus a year or so later, they said all high voltage pile batteries were no longer available. Note: This battery is still functional in an old precision GM counter. Admittedly it is rarely used beyond making sure it works a couple of times per year. Still, the shelf life is amazing.

Now I just don't know the exact date of the end of pile batteries by Ever Ready.

Richard Hull

Re: Cutting edge GM counter (1953)

Posted: Mon Jun 24, 2019 12:31 am
by Rex Allers
At risk of taking this a bit farther than it needs to go...
I'm now puzzled by how one should interpret the Eveready date codes.

The battery I had has a code of 1205 and other info makes 05 = 2005 seem reasonable, so I assumed the first two of 12 meant the code was for
1205 = Dec 2005

Now you provide us with an example of 9706 and again your purchase info seems to indicate the 06 = 2006 is ok. But the 97?

In a year, only 12 months or 52 weeks but too many days for two digits. From above examples I assume we can trust the last two as year but the first two have me stumped.

It'll be OK with me if we never know the encoding, but I thought I'd share my puzzlement.

Re: Cutting edge GM counter (1953)

Posted: Mon Jun 24, 2019 5:54 am
by Richard Hull
I have lodged the question of when Pile battery production ceased with Eveready on their website. They note that it may take 3 days to respond.
If they do, I will add this info to this thread.

I did find an image of the rare #497 - 510 volt photoflash battery. It was not a very big or heavy battery as it was worn in an over the shoulder leather bag with a cord to the pentax strobinar flash attached to the camera. Note: This one is from the 60's or 70's as it still pictures the cat leaping through the 9...Note: The bold claim about bouncing back after use on the label (See bottom of image)

Of great importance is there claim on the label in this image about leaping back to power after use. (nine lives) It is true!! I found this out on my discharge tests in my GM counters I make for sale. My counters use a common 9v transistor radio battery for power. Unfortunately with the bright blue, back lit, 4X20, LCD display, the drain is ~80ma. This far exceeds the recommended load, even for an alkaline battery. I ran 5 repeat testings of the two for a dollar, 9v carbon-zinc, Sunbeam, (chicom), Dollar Tree batteries. My counters work on 5 volts and I use a low drop out regulator on the circuit board. In this manner, I can drain any 9 volt battery down to 5.6 volts and the counter will keep working.

The carbon-zinc, Dollar Tree batteries for continuous on-time lasted 13 minutes before crapping out on the first run. I ran the second battery for 14 minutes before it was below 5.6 volts and died. The next day, I went on testing alkaline and NiMh 9 volt batteries. On the third day, I grabbed one of the dead Dollar Tree carbon zincs and ran the test over again. To my amazement the starting voltage was 9.2 volts and the battery again ran for 14 minutes! The second battery ran for 14 minutes again as well. Given a day off, they fully recovered! Sweet...

I mused over this welcome, but puzzling outcome. All 9v carbon zincs are pile batteries. Remembering my detailed knowledge of these batteries chemistry, I remembered the polarization of carbon zinc cells about the carbon anode, and the chemical solution to combat this cell resistance increasing phenomena. With the heavy loading forced on the small battery, the de-polarizing chemical near the anode was simply over powered and could not keep up with the load demand. The battery internal resistance increased killing its output to the load. With a rest,the ever mobile, diffusing, depolarizer did its job at leisure and the cell was like new again. This action allowed the cheapo batteries to restore about 6 times before the voltage and run times were reduced to under 10 minutes. The "nine lives" wasn't far off the mark, just due to the nature of carbon-zinc chemistry!

Richard Hull

Re: Cutting edge GM counter (1953)

Posted: Tue Jun 25, 2019 7:53 am
by Richard Hull
For Rex and others amusement and I think amazement, I have included the URL to the PDF of the entire GE neon lamp application manual. page 62 gives information on the ring counter. I, long ago, printed and GBC bound the entire manual. Those guys of the 50's and 60's made these little lamps do a lot of stuff far beyond just being indicators! ... dition.pdf

Regarding the Eveready inquiry...... Idiots!..... I got a response from the complaint department which was, apparently, tasked to answer my question. "we don't no nutin' about no old battreees"..... "if you would like us to push this up to the headquarters division, please let us know in a reply to this message"..."note if you do not reply within 2 days your query number xxxxxxx will be closed."

I replied to push it up the chain....The beat, like the bunny, keeps on going and going and going....While the cat remains dead.

Richard Hull