My latest project -

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It's built around this kit and a couple surplus Soviet Geiger tubes (one for low-level measurements, and one for oh-shit-we're-all-gonna-die measurements) - all packaged inside a Hammond die-cast aluminum case.

One of the neat things about this kit is that not only is it capable of displaying instantaneous radiation levels and calculated dosage rate (32 counts per minute and 0.02 mR/hr in the above picture), it also has a second display page that can show long-term averages:

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(In this case, it's displaying a 1-minute average of 16 counts per minute and 0.01 mR/hr, and a 60-minute average with the same values).

The 60-minute average is probably the most useful for monitoring background radiation levels over the long term - In my location with my particular Soviet SBM20 Geiger tube, it's always 16-18 CPM, no matter what.

This contrasts with shorter average intervals, which randomly vary quite a bit from moment to moment.

There are also programmable setpoints for CPM and mR/Hr that will sound an alarm if they are exceeded.

The remote control allows various parameters to be user-adjusted - I added a switch to disable the IR receiver when the remote isn't being used.

With the backlight turned on, the unit only draws about 25 mA at 5 volts - so it'll run for several days on a $5 Wal-Mart rechargeable USB power pack (shown attached to the back of the unit):

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Small magnets secure the power pack to the unit, allowing it to be easily removed when not in use:

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Normally, it sits on my workbench without a battery pack attached, running 24/7, powered by a USB wall wart.

Total parts cost: $110, maybe?

That's easily doable.

It's built around an Arduino "Pro-Mini" processor, running a plain ol' Arduino sketch program - open-source, and easily modifiable by anyone familiar with it.

From where did you source the handle?

(And how many mAh is the battery pack rated for?)

The handle is just an ordinary "designer" kitchen drawer pull. IIRC, I got it at Home Depot.



It's available in two thicknesses - one is 2300 mAH at 5 volts (which is what's shown in the pictures); the other is 4700 mAH.

Similar USB power banks are available in a bazillion different sizes and shapes - Most of them are very inexpensive for the amount of mAH they deliver.

Note that there is a trick to getting most USB "power banks" to work with a device that only draws 25 mA.

Normally, the pack needs to see a load of at least several hundred mA, or else it will shut itself off after just a few seconds of operation.

To fool the power banks into thinking that a much larger load is present, I built a small timer circuit that momentarily applies an additional 190 mA load for 0.25 seconds every 2 seconds.

This keeps the power bank "awake", without being much of an additional burden on it.

That's really cool. I like the old-school toggle switch based UI as well.

I take it the IR lets you configure the alarm levels and such?

^Yep.

Ingenious solution to the auto-shutoff problem…

Cool!


Now how do you test that it works?
Or maybe, works accurately?

There really isn't much testing to it.

Basically, you tweak a pot so that it supplies the voltage required by your particular Geiger tube.

After you do that, you're pretty much assured that your tube generates X clicks per minute in the presence of Y amount of radiation.

There is also a function that allows you to enter how many counts per minute your particular tube produces in order to equal 1 mR/hr of exposure.

The CPM : mR/hr ratio for most common tubes is available here - Just look up your particular tube, and enter the corresponding ratio.

After that, the software does all the work.

I recently switched from oldschool tubes to scintillation radiation detector. Much faster response when hiking around and rock hunting.

I also have a bunch of calibrated detectors from a lab. The idiots at work were calling hazmat places trying to get someone to collect the older but still perfectly functional units and idiot hazmat people were referring them to the state for radioactive waste disposal. I told them I knew a place that would take them and I’d drop them off.

I had to have radioactive iodine treatment for my thyroid cancer.  They want you to stay isolated because the radiation given off at first can be hazardous to others and pets.  

Anyways, before I got the treatment, I got this:






I was surprised at how well it worked.  It has a built in alarm for high radiation readings.

So when I got home from the treatment and stepped up on the porch, we heard a loud wailing coming from inside the house.  Seems this thing went bat crap crazy when I got anywhere near it.

For less than $100, it was worth the money.  As the days went on, I could see the radiation going away quickly.  Oh, and pee would set it off like mad.

Hahaha, I got sound turned off, alarm set for probably 100 or 120mSv. Just log and plot everything using gps. Definable add gps logging to yours. Can always read the sd card and plot it or set up AWS microservice.

This particular version is mostly for stand-alone applications - i.e. as a modernized survey meter. Lots of construction examples here.

Wi-Fi is an option, but probably better suited to a version specifically designed for remote reporting - like this.

Nice.  I debated about cobbling one together along the lines of the bgeigie Nano kit that was being distributed shortly after Fukushima, would be fun to link it to the GPS radiation mapping project. I ended up buying a unit with the same detector and learned my new granite counter tops were probably not something you wanted to sit on for long periods of time

What kind of scintillation detector do you use for rock hunting?

Some folks say that a Ludlum Model 3 can be found for a reasonable price, but I have no experience with this stuff so I wouldn’t be sure of finding something that would do the job well.

The Model 3 is an absolute tank - almost indestructible - and you can even still buy them brand-new from Ludlum's.

However, it doesn't include any sort of detector - so that's an additional expense.

I'm not interested in really low-level radiation - Just any changes in normal background radiation right up to anything that might kill me.

That's why I use GM tubes instead.

I am just starting to discover the “rock hounding” world - with fluorescent mineral collecting being my main interest.

I don’t understand it well yet, but apparently with some minerals if trace amounts of uranium are present it may activate fluorescence where otherwise no fluorescence would occur.

So I’m thinking that being able to detect radiation (gamma only? Maybe also beta?) might be a useful adjunct. Also I’d be interested in checking my so-far fairly small mineral collection to see if any of those specimens show signs of radioactivity.

I do have a hobby-level gm tube detector that I built from a kit many years ago (and which I just pulled from my junk box as a result of reading this thread) but I suspect that it will be inadequate for the task.

My newest one is a russian radiacode101

Do you use it standalone or with a smartphone?

Do you carry it in your hands or attach it to a pole of some sort and swing it around like a metal detector?

That's awesome OP!

When I was in training for my job they had us in a simulated RCA (Radiologically Controlled Area) it was inside a classroom just to learn proper dress out and how to doff everything when you're done and what kind of markings we'd be seeing inside the plant. They had us frisk out at the end, the instructor hid a Fiestaware dish under the procedure you were reading as you are frisking, the detector went apeshit and he goes "What did you touch?!" and then starts laughing and lifts up the paper, and tells us about the history of the Fiestaware stuff.

I finally ordered the Radiacode 101 scintillation detector - looking forward to some scintillating discoveries.

And about a month later I received the scintillation detector (mail service from Russia is slow) - just hooked it up to a new android phone a few minutes ago and I ran the app for the first time.

I’m looking forward to trying some gamma ray spectroscopy.

After just a quick scan through part of my (mostly) fluorescent mineral collection I’ve located at least one specimen that exhibits count rates that are about 5X the 3-ish counts per second that seems to be the background level here - not high enough for health concerns, but it would be interesting to identify the isotope(s) that are contributing to that elevated rate of activity.

Still have lots to learn, including making sense out of the different units for measuring and quantifying radioactivity, doses, and the like. Also need to brush up on the periodic table and radioactive decay nuclide sequences and isotopes.

Actual calibrated emission sources are a bit expensive, but I might gather some samples of some common emitters such as thorium (welding rod or old lantern mantles), old radium watch hands, uranium glass, etc.

(Updated for parts sources)

@skibane

Can you recommend a commercial dosimeter/counter that would be simple to use for detecting dangerous levels in a post nuclear accident or similiar situation. I'd like to build one like yours but my skills at such things are pretty limited.

^There's several mentioned in this thread.

Ideally, you want a model that's capable of measuring high levels of radiation, because that's what you might expect to encounter while attempting to minimize your exposure to fallout.

A lot of the hobby-grade stuff only works in low-level conditions, and would be worthless after a nuclear attack or major accident.

What did you do for the display?
The blue type shown with the kit are both a pain and can be hard to read.

Is yours some sort of pin-compatible replacement?

^Yes, the green (or "yellow") 16x2 pixel displays are pin-compatible with the blue ones - They aren't as popular nowadays as the blue ones, but you can still find them on ebay, from Aliexpress, etc.

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Several of my kits were old enough to be shipped with the green ones. Another one was shipped with the blue, but I just substituted a green one instead.

IIRC, this is what I bought as the green substitute.

ETA: You want the display version with a HD44780-compatible pinout, not the IIC-compatible version.