The tube you pointed out on the CDV-700 schematic is NOT the G-M tube. It is a corona voltage regulator tube to stabilize the high voltage output from the supply at around 900V. The G-M tube is V1 at the top left of the schematic, type 6993.
And those Corotron (proper name) voltage regulator tubes go bad and allow the voltage to go high, which can destroy the pulse transformer (T1) which is not to be found anymore. That Corotron VR tube should be replaced with a zener stack voltage regulator ASAP. I suspect that's why so many are no longer working. eBay sellers have pre-built zener stacks available. It's an easy direct replacement. Help a friend, pass the word.
You might want to take a look at the review of the GC-01 I just released on my channel. Sadly the product has just switched to a far inferior GM tube and this even includes the white-label versions of this device. I contacted the company here in China (where I am based) and they confirmed the change. Such a shame, its was pretty OK for a low cost counter...
You will be surprised if you take a Geiger Counter into a antique shop, some paint on old vases is radioactive, also the white piece of fabric that is used as a wick on older gas campinglights is radioactive.
my friend took his geiger counter to the camping store and the thorium lamp mantles all hanging on the shelf together gave a really strong signal. made the store employees freak out.
@@IMSAIGuy There is a guy I met in an antique shop who has been restoring the camping style lanterns for years. He collects them of course. I showed him the geiger counter response on some of the ash in the bottom of one of his. I always try not to alarm people but educate them on safer handling. I explained that it's nothing to freak out over but be careful to wash hands after handling/work and avoid inhaling the ash dust. Same thing with the old radium clocks/watches. If you're looking for a nice test source, it's easily found in vintage orange pottery because it's mostly a low energy beta emitter with quite nice high CPM. Very little gamma.
There are a number of these devices labeled “FNIRSI”, I recently purchased the DCO-TC2 component tester & “oscilloscope”, the oscilloscope is useful as a visual logic probe or signals which are in the 10’s of kHz range.
Up until 1969 here in New Jersey we had a local chapter of civil defense which was still existing. Amateur radio operators were members and we used to hold a bi monthly net on 10 m a.m. to have each county check in. I still have my membership card my ID was one November 5
There are two main types of detectors, GMtubes and scintillators. The GM tubes are less expensive, but orders of magnitude less sensitive. In addition if GM tubes are hit with strong radiation, it can make the tube somewhat deaf afterward. Units with the scintillator have both greater sensitivity (ability to detect weak radiation) AND the ability to be used with stronger radiation sources.
@@Anthony_Matabaro_3D_360 You are welcome. I've been shopping for counter myself and was wondering what the difference is and why the difference in price. I'm planning to get a low end scintillator counter.
I am lucky to have both of these units, the CDV-700 inc the kit CDV-777 and the FNIRSI GC-01. The calibration on the side of the CDV-700 is useful as I have tested both the CDV-700 and the GC-01 units and I have got the same test reading. Be aware! there are some GC-01 look alikes without the brand name of FNIRSI that have the inferior tube inside and other youtube videos shown they are not so good.
The F-NIRSI gadget shown at 8:30 is useless in bright sunlight as the display cannot be seen. Also the internal battery has to be charged which is another negative if using outdoors, when we would usually just swap out the dead battery. Not a practical device at all, just a ice indoor toy.
I also thought of adding a piezo. Perhaps try 2.5 khz resonant freq ones rated 30v p-p. They were the best sounding for CDV700 anyway. Radio Shack part number 2730073 can still be found online/ebay etc.
@@nefariumxxx I've used them before, (I had one as a doorbell. LOL). But it's too big to fit inside the case. I am waiting to see if anybody else tries it first. I'm not risking mine. Ha ha.
Isn't that front side red LED the actual detection indicator? You should try attaching a small piezo speaker to it. I might order one to try that out. It's a nice unit, but not having an audible output is a major design flaw as it also serves as a, completely analogue, way of verifying that the detection circuit is OK.
The CD V-700 also came with a "check source", a bit of a radioactive isotope under a sticker on the side of the unit. The isotope varied with the maker; depleted or natural uranium was common, though the Instruction and Maintenance Manual for the Lionel Model 6B indicates that a "Radium D+E beta source" with an approximate half-life of 22 years is present under the nameplate. This produced, at the time of installation on the machine, about 1-2 mR/hr adjacent to the source, a value which was clearly visible on the analog meter as well as audible via the headphones that accompanied the units. Measured with the probe's beta window uncovered and the probe directly in contact with the operational check source, this is about 100 times normal sea-level background levels of radiation, and similar to the near-field from a uranium oxide-glazed red Fiestaware saucer. The level drops back to background levels a few feet from the source. Since the half-life of the different operational check source materials used varied and since all CD V-700's were manufactured prior to 1964 and are now approaching a half-century old, the amount of radiation emitted from the source may be much lower than when the unit was originally issued. Therefore, accurate calibration via the source cannot be assured.[2]
Not Sr-90 on American stuff. That was used on foreign counters though. American Civil Defense stuff mostly used depleted U and also Radium 226. Some of the more fizzled out test source stickers even used "Radium D+E" (From ORAU) "Radium D and radium E are the historical names that Ernest Rutherford used for lead-210 (Ra D) which has a 22-year half-life, and bismuth-210 (Ra E) which has a five-day half-life". Now good luck remembering all that. :)
@@loupgarou1261 yeah, they list the various flavors on the ORAU page if you google it. I don't see my ENI brand mentioned right now but remember it also being depleted U.
Question, how many years would a geiger counter with j321 TUBE , be reliable/functional/accurate if the geiger counter is stored unused compared to if the geiger counter is kept on 24 hrs per day as a background monitoring device ? ?
The CPM values are probably a lot different and will depend if you have the beta shield open or close on the CDV700 probe. The FNIRSI has a decent response but it's not going to be super sensitive because it uses a glass walled tube and it's shielded inside the plastic case. Glass and plastic both block low energy beta counts. The stock CDV700 uses a thin metal wall tube but it's also not all that sensitive deliberately. The FNIRSI is a good value for the money. Just too bad the developers really dropped the ball on adding a "click per count" or source finding mode. It could be modified possibly by running a couple wires from the flashing LED to a piezo disc clicker. Try a 2.5 khz piezo perhaps.
If you have stone countertops in your kitchen you might want to check them local news channel did an article on how radioactive some of the stone material can be.
Holy crap. I have one of those but never looked closely enough at it to notice the test source on the side! I guess I saw the sticker but never read it.
Low sodium salt (~ 66% potassium chloride. ~0.012% of natural potassium is potassium-40), is a simple easily accessible source of beta and gamma radiation (~three times background levels for most of the world). Potassium is nothing to worry about, your body maintains a near constant level of potassium, and any excess passes right through your system (~0.4% of the mass a human body is potassium, therefore ~0.00005% is radioactive potassium-40). So you are really talking ~0.05 grams (~0.0018 ounces) in total distributed through the entire body.
This guy added sound. He is speaking Russian i think, but i managed to follow his hack. He connected a resistor to presumably to the base of the transistor feeding the audio alarm to the piezo. Then other end of resistor (probably 10k) to LED. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-ox1YMzAl3zM.html
The problem with Geiger counter, is that it only detects the magnitude and not direction. I wonder if we can use 2 orthogonal placed tubes or 3 for 3D to detect direction of the radiation? Each tube should be placed inside radiation shield, ie, lead, so that it only receives radiation in one direction, Say X direction or Y direction or Z direction and based on the relative strength of the detected radiation we can display the direction on a LCD screen, with a vector. Also, we might be able to use reversed biased direct band gap diodes or photo cell instead of Geiger Tube. In that case if we use direct band gap photo cell we do not need to use radiation shield, because side of the cell is much smaller than the front side. So radiation detected perpendicular to front surface is many dB greater than the radiation detected parallel to front surface.
@@IMSAIGuy Yes from the source, not the detector. Say you have a sample of radiation material in one corner of your room with normal Geiger counter you should go around the room to find it, but with directional Geiger counter the arrow leads you to it. In space such a directional Geiger counter, if you block the sun direction, could lead to detection of location of super Nova or other cosmic activity. We can also create directional gravitational wave detector with placing 3 gravitational wave detector on the 3 corners of a triangle in the space, say one on the earth another on the moon and a third one on say mars. By comparing the time of the event given the lag time, we can detect the direction on gravitational wave, the same way we detect source of earth quake using triangulation, so we can point our telescopes in that direction. We also can prove what is the speed of gravity, speed of light or infinity as quantum mechanical event.
@@aduedc if you can detect across the room with a geiger counter you are about to die. they only detect within a few inches. if you really want direction, just put it in a shielded box and poke a hole in it
@@IMSAIGuy you just need more sensitive detector. The mechanism of detection is when a particle or photon hits an gas atom, the gas molecules gets ionized and the ionized particles accelerated toward positive and negative terminals, and on their way they might hit other molecules which creates other ionized particles which amplifies the current. You can have the same thing with avalanche photo diode. Now the larger the area of Geiger tube or avalanche photo diode, the greater the probability of capturing the photon or particle, which means greater sensitivity. Therefore, to increase sensitivity you either have to design larger tubes and diodes or put several of them in parallel. When I drive from Los Angeles to San Diego On I5 I pass by San Onofre decommissioned nuclear reactor, I can detect the radiation by my cell phone's CCD on the high way in my car and I have not died yet! My phone's CCD is not very sensitive radiation detector. I just use android app that I bought for 5 box.
You got get a Radiacode 101, pricey, but very sensitive got mine directly from Russia, it took 10 days from Moscow to my door.... This unit can pickup radon while riding my bike around the neighborhood, while logging the location to a Google map on the app, and can detect from 30ft if someone has radioactive tracer in there body.... Very awesome.....
Price I found on that is in the $600 range. It is a scintillator type counter though. More sensitive to low levels and more resistant to damage from higher levels.
@@IMSAIGuy I was looking at the Radiacode 101 which is also a scintillator based counter with decent electronics for about $600. The B20 strikes me as way overpriced in that they market to industry, universities, and other institutions with deep pockets. I'm sure it is a great piece of equipment if you can afford it.
Those are cool but it doesn't detect Radon gas directly. You are mostly detecting background radiation coming up from the earth/bedrock granite as well as cosmic/space origin. Radon detectors use different technology. I use a device called Radon Eye because I live in a high radon zipcode. If you want to detect the secondary daughter particles from Radon, you can take a wipe off the whole car windshield right after a fresh rain following a period of dry weather. Radon progeny in the decay chain gets "scrubbed" out of the air by a fresh rain. The radon secondary particles (contamination) will adhere to the wipe which can then be detected by your Radiacode directly.
@@loupgarou1261 maybe so . But the one I bought was the little hand held one. I was looking for instructions. You put up click bait that had nothing to do with the one I was looking for information for.
