Detectron Geiger Counter

Probably would, but may not for very long. Why not an inverter with an output of about 90 VDC? The current is not very great, you could probalby bodge one together easily enough.

Ok, ignore it. I was hopeing for power supply.

No. I meant high voltage battery positive lead. If there's motorboating there, then the power supply may need to be filtered.

If that shows nothing useful, follow the signal path from the GM tube (after the coupling capacitor so that you're not looking at 900VDC) to the first grid, to that tube's plate, to the next grid, and so on. You should be able to see the motorboating.

Then, trace it out. From the photo, it looks simple enough.

It's a 900VDC regulator. Same as Victoreen GV3A-900.

See if there's any oscillations cross the tube with a high-voltage probe. It could be acting as a relaxation oscillator (as in a neon-lamp oscillator). Solid state replacement:

More for the collection (but nothing useful):

Here's an eBay listing that has expired.

Ummm... check out the gas and kerosene mantles from China. Some are hot:

Incidentally, I once sacrificed one of my radioactive thorium Coleman lantern mantles and ran a side by side comparison of the brightness with a current non-radioactive zirconium mantle. The radioactive mantle was MUCH brighter.

I like to use KCL (potassium salt, lite salt, or low-sodium salt). The Potassium 40 is radioactive (450pCi/gram):

It's not very hot but works well enough with a GM tube. Also lots of fun going to the market with my 1950's GM counter. I once found some brand of sea salt that was really hot, but it had been withdrawn or recalled before I could return to buy some.

While at the market, try brazil nuts, acorns, and bananas. K-40 but only when grown with massive overkill doses of fertilizer. Also try cat litter. They all show up hot with my scintillation counter, but are very weak with the GM tube.

If you go to the hardware store, check out the high phosphate fertilizer. The stuff has uranium, K-40, thorium, radium, and who know what else in it.

While at the hardware store, see if they have any tungsten stick arc electrodes. They have some Thorium mixed in.

At home, if you have a dark colored granite counter top, you'll find it somewhat radioactive from uranium.

The problem isn't so much the radiation. It's the radon gas that it produces.

Got any pottery or kitchen plates with a yellow or bright orange glaze (Fiestaware)? If so, they're uranium oxide.

Got any old cameras or eyeglasses made between WWII and about 1980? Most lenses have thorium mixed into the glass to increase the index of refraction. These are really weak and will only show up on my scintillation counter.

Got a heavy scotch tape dispenser with a sand-epoxy mix in the base? The sand has thorium mixed in.

Got an old static eliminator for removing the static electricity from old vinyl records? If so, it's quite hot with Polonium.

More:

See section on food.

In message , Jeff Liebermann writes

Be aware that, while "bodge" and "botch" tend to get used interchangeably, "bodging" and "botching" are not the same thing.

A "bodger" is a skilled, itinerant wood worker.

A "botcher" is someone who fakes doing a proper job of something.

If a kludge provides a functionally adequate (but inelegant) solution, I'm not sure whether it is really a bodge or a botch.

At this point, I think you're right - it's probably issue with the B+ supply, probably a combination of poor filtering and inadequate output current. After tracing out the schematic that's about the only conclusion I can come to. I'm going to take a break from this for a while, and then try building a better power supply, and I will post back with the results. There was something of interest in those links you posted; one specified a

Ok, I'm lost in the translation. However, it's good to know that the Kings English has multiple names for what I do naturally when confronted with a technical problem. Such multiple names are a sign of sophistication and tends to identify what a society considers important. For example, the Eskimo's have multiple names for different types of snow. In Yiddish, we have multiple names for the different types of "idiot". In government, there are multiple names for the different types of taxation.

I'm sure something profound can be extracted from all this, but I don't want to ruin a nice weekend by attempting to think.

Chris F. Inscribed thus:

Since you get clicks when the tube is not connected, have you checked the EHT supply. It probably has bad caps in there. Something breaking down as the EHT rises.

Jeff Liebermann Inscribed thus:

Hey Jeff, I've several old valves (Tubes) that are marked as containing "Radio Active Material" with a "Do not Break Glass" and a yellow sticker on them. CV number marking. Any ideas ? They are stored in a box somewhere. If I can find them I'll come back with the CV numbers.

Actually, the way this circuit is designed, any ripple or pulses in the DC supply will be picked up and amplified the same way as pulses from the GM tube. I guess it was never designed to operate on an AC power supply, but I'm sure there's some way areound the problem. I've replaced most of the capacitors (all are high voltage ceramics).

Probably cold-cathode rectifier tubes, equivalent to types like 0A2, 0D3, etc. I have at least one American-made 0A2 that has a radioactive symbol on the box, and the tube itself says "Contains less than 0.03 microcuries of Krypton".

Chris F. Inscribed thus:

Sods Law ! It will be the one that you didn't replace. :-)

Did you read the information in this link? Scroll down to the discussion on the regulator tube.

The 900 volt regulator tube operates in three regions; corona, glow, and arc. It is sensitive to the high voltage supply conditions, i.e. ripple can cause it to oscillate between the modes. Also, it is sensitive to the filter capacitance.

You rang?

Tubes are what you roll the toilet paper upon. Valves are what controls the flushing. What more do you need to know?

My guess(tm) is a gas filled thyratron or regulator tube/valve/whatever, where the gas is slightly radioactive to decrease the ionization voltage. The cathodes were also made with thorium:

The 5841 voltage regulator is one of those that is filled with some radioactive gas. The differences between the various versions, which breakdown at different voltages, is the amount and type of radioactive gas or material.

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So what have you found for a long-term test source , high enough emitter at a repeatable distance, to say give a count at least 5 times more than background? I've managed to lose my old broken gas-lighting mantle I had retained for this purpose

Homer Simpson laughing at the "Run for the hills" alert level on the warning sign at the power plant. "That will never happen." Lenny asks him if he thought the power plant was safe. "No, if the plant blows up, there won't be any electricity to power the sign."

Jeff