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Has anyone ever come across a Geiger counter that works with Apple II? I remember seeing one in an episode of Mr. Wizard (season 4 ep 13), but I've never actually seen the peripheral or the software. I can't find a clip online but I'll upload a screenshot in horrible definition. It might have a dedicated peripheral card too, the cable is RJsomething though I suppose it could just be using a DB9-RJ45 adapter.
Helpfully, the peripheral is shown in a clear plastic case, and there is no microcontroller visible inside.
This means that the signal to the Apple II must be a straight TTL pulse, which could connect directly to the game port, depending on the resolution required. There should be Geiger counter kits available with a TTL interface, even today.
Here is one possibility (need to check the datasheet), Pasco Corp SN-7927 or SN-7928.
I can't help you with finding the software, though.
For another approach to educational science-lab stuff, see the Bank Street Laboratory kit.
I've looked at the photo in post #1 and it seems that the Apple II just counts the impulses from the Geiger counter and shows counts/time statistics (the bargraphs). This could be a trivial programming exercise if the Apple II had a real time clock / event counter peripheral but it does not have any of that (unless a specialized slot card is added).
Post #2 of 'robespierre' suggests that the pulse from the Geiger counter just may have been connected to a game port pin. This could be correct but also implies assembly language programming with a controlled timed loop (aka "CPU cycle counting"). There is no way to do this counting in BASIC without missing some counts. This complicates the task. But it sure can be done (the whole DISK II system is based on cycle counted programming techniques).
So the other possibility is that there indeed was a slot card with a counter on it. This could be a very simple circuit, but it would allow use of a trivial BASIC program which just PEEKs the counter contents which also would clear the counter.
The obvious tradeoff is hardware expense for the slot card vs. software development expense for the tricky, cycle counted coding.
What is more likely ?
I dare a guess that a slot card would not increase the costs for the whole Geiger counter package too much, and that not all too many of these systems were sold, so complicated coding may have cost more. In my eyes it looks more like an educational toy for use in schools. There were some slot cards made for this purpose, which had measurement and control ports, for use in "Science" classes, but I don't have any of those.
Just as a general remark, these simple Geiger counters are almost useless for professional work in nuclear physics, which demands better radiation measurement instruments than Geiger tube based ones. So it's highly likely that we indeed are dealing with an educational toy.
- Uncle Bernie
Yes, Geiger-Müller-tube based detectors are commonly used as dosimeters or survey meters for health physics purposes, while scintillation counters have far more sensitivity and can even distinguish different photon energy levels as a kind of histogram.
A woman called "bionerd23" has some very interesting videos showcasing two of the finest GM-tube meters—the Automess 6150AD, and the Gamma-Scout—used during explorations of the Chernobyl exclusion zone. Both these meters are still being made in Germany, with production lasting for decades.
A Geiger counter that is not portable has practically no application outside a basic educational setting.
I was considering building a one-off ESP32 SoftCard with a Geiger counter in the prototype area and auctioning it on eBay as a promo for the regular card. What really dissuaded me is the high voltage required to operate the Geiger–Müller tube, which on a Apple II expansion card would be rather exposed. I didn’t want to deal with the possibility of someone getting shocked or electrocuted.
In post #5, "CVT" wrote:
" What really dissuaded me is the high voltage required to operate the Geiger–Müller tube "
Uncle Bernie comments:
This danger can be mitigated by potting the HV generator in some suitable epoxy compound. Which leaves the contacts on the Geiger Mueller tube . . . which on Soviet Union types (i.e. SBM-20 found in the RKSB-104) are on each end of the tube, so some plastic cap with an internal contact spring would be needed to isolate the HV from the user. This could be done.
The whole HV generator / Geiger Mueller tube / pulse conditioner could also be installed in a plastic tube with an open window for the tube. A cable supplying some low voltage DC to this instrument head with one wire for the pulses to the counter could end in a 3.5mm stereo jack which either plugs into the Apple II slot card or a portable unit.
But the purpose of such a Geiger counter is dubious at best. Never mind that people tote them around in their youtube videos of the Chernobyl exclusion zone for dramatic effect, and never mind some companies still make them, even if they happen to be "Made in Germany" I regard them as wasted money - see my "general remark" in my post #3.
Here is my rationale behind this statement:
Unless we have a global nuclear war or another Harrisburg / Chernobyl / Fukushima incident, it is highly unlikely that the common person ever gets near anything that is radioactive enough to make a Geiger counter / personal dosimeter give out an alarm. For people working in nuclear facilities, the story is different, but they are given professional grade dosimeters which today are very sensitive and accurate and not based on Geiger Mueller tubes, as they are flat and credit card sized electronic instruments, at least those who I have seen. The older pen type dosimeter which needed high voltage charging to reset is long obsolete. As the story goes, these would be inserted briefly into the charger before being read out, so the personnel working in the facility would have a much lower total dose in their official health documents. And never know the difference ... I was told that the modern electronic dosimeters can't be tricked that easily so the employees of nuclear facilities now do know why their offspring looks so ... weird ;-)
So where is the usefulness of a Geiger counter for common people (other than the one science class in high school where the three types of radiation are demonstrated . . . I wonder if they still allow pupils to do the experiment and handle the radioactive sources if they teach that subject at all anymore).
The only - "useful" - theoretical purpose of a Geiger counter for common people is to test their food for radiation, especially if they live in the parts of Europe which got the Chernobyl fallout. The RKSB-104 was advertised to be able to do such measurements and sold in huge numbers. I happen to have one but never was able to prove that the "food" in Europe actually qualifies as "lightly radioactive waste" which by law should be safely disposed of in stainless steel barrels and then dumped into a deep mine shaft, instead of being eaten by the people. A friend of mine who worked in a nuclear research facility at the time told me he can prove the "food" sold to the unsuspecting people indeed was lightly radiactive waste, by using their professional measurement equipment in the lab. I also gave him my RKSB-104 to verify it against one of their calibrated radioactive sources, and he told me it was in spec. So it was not a defective RKSB-104. It worked. But it could not "see" the danger lurking in the "food". As a consequence, I imported all my food from overseas before I left Europe for good.
Draw your own conclusions. If you have a Geiger counter which is able to tell you that your "food" is radioactive, you already are as good as dead. The only open question then is how long will it take until the cancer caused by that radioactive "food" gets evident. 10 years ? 20 years ?
So why spend the money on such a useless thing ?
What you really need to check your food for radioactive contamination is s sensitive scintillator with a photo multiplier tube, and this can also tell you the energy of the radiation, so it is possible to identify which radioactive isotope(s) are in the sample. Such a setup can be home built, if you use surplus new old stock photomultiplier tubes, and buy a good scintillator crystal. The mechanical construction of the measurement chamber is difficult, as absolutely no ambient light may enter it, but it can be done if you have good metal working skills and precision metal working tools.
I happen to have a few photomultiplier tubes in my basement, intending to build such an instrument, but lack a good engine lathe to make the metal parts. Yet another unfinished project ...
- Uncle Bernie
That will work, but it might be just above the amount of effort I am willing to put into a one-off.
As far as usefulness of Geiger counters goes – this is not what this topic is about, so I’ll just say that they are one of those things you should buy when they are almost useless and hope that they don’t become useful all of a sudden. Major nuclear disasters seem to happen every 25 years and during the last one (Fukushima) the $25 Ukrainian dosimeter reached $800 on eBay.
During the previous one (Chernobyl) my father happened to have a Geiger counter at his work and he found it super useful, while living in a communist dictatorship that would purposely hide the radiation levels from the public. He managed to warn friends and family and keep his foolish 10-year-old son from climbing trees all day.
In post #7, "CVT" wrote:
"... Geiger counter at his work and he found it super useful, while living in a communist dictatorship that would purposely hide the radiation levels from the public."
Uncle Bernie comments:
Not only communist dictatorships lie to their people, Germany did the same (lying) and they claimed that the "lightly radioactive waste" into which the Chernobyl fallout has turned the locally produced food was "safe to eat" - "there is no danger for the public" - all lies, lies, lies.
I've been there when the fallout came and stayed in the research lab I was working at the time, to avoid the radioactive rain. After the rain was over, I went home and in the same night built my own Geiger counter using a tube I had. This contraption was not calibrated in any way, but it would "rattle" badly when held near a puddle of that rain water. Proof enough to better stay away from that place.
In the months and years after that event I tried to measure contaminated food they sold in local supermarkets (this "food", by Bq/kg, did indeed qualify as "lightly radioactive waste", this was not a joke I made). I acquired several Geiger counters (the RKSB-104 in Y1991, 5 years after Chernobyl) but found all of then lacking in their ability to accurately measure the radioactive contamination at low levels. Using proper sample sizes and measurements over long time, subtracting the background radiation, and using the beta radiation shields to discern gamma and beta, the statistical calculations yielded dubious results at best (std deviation too big / confidence interval too small). This means that I could not bring the food back to the vendor for a refund, claiming it's radioactive with X Bq/kg. Grocery clerks do not understand radiation and confidence intervals of measurements.
While the very same food samples tested by my friend working at the nuclear research lab (where he could borrow / use more sensitive instruments) clearly showed that the "food" indeed met the criteria to be "lightly radioactive waste". And the people were buying and eating that radioactive waste. And paid with their health. Just look at the explosion of thyroid diseases in Europe (i.e. Morbus Hashimoto, Thyroid cancers, etc., from a few per year to millions of people getting them).
This experience showed me that Geiger counters are of limited usefulness. They are able to warn you about places or objects which are so "hot" that you better stay away. But they are not sensitive enough to assess low level radioactive contamination of your food and drinking water. And this is the real, long term killer (incorporation of radioactive isotopes).
The fact that prices for Geiger counters and Geiger Mueller tubes went through the roof in the Chernobyl aftermath is no surprise, just look at the prices for gas powered generators, gasoline, food, bottled water, etc., in the aftermath of any hurricane or earthquake. It's the "market" and human greed.
I made the case of usefulness (or the lack thereof) of Geiger counters for use by common person to preserve these experiences and lessons learned for posterity and for anyone interested in Geiger counters for the Apple II. If you get one for a song, fine. But IMHO it would be unwise to expend lots of money to buy or build one just because your interest was aroused by the OP. I do have some in working condition and found them to be useless for my application(s). But if you intend to navigate a radioactive wasteland after a global thermonuclear war, go for a Geiger counter. I do not intend to do this as I live near a primary nuclear target and will get vaporized in the first seconds of such a war. No need to keep Geiger counters around me.
- Uncle Bernie