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Stepping up the voltage for a Geiger Counter

Xobtah

Oct 16, 2017
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Hi!

I'm very new to electronics, I made few projects to get used to it, and I'd like to make a Geiger counter since I alreay have the SBM-20 tube, so the only thing I need to make it work is to figure out a way to put 400v from 5v into it (then it's more or less coding sutff left, and I'm a programmer, so it's all good).

I'd like to have your opinion on boards like this:
https://nl.aliexpress.com/item/Boos...ersion-radiation-sensor-400V/32729871570.html
Do you think it may be a scam?

Otherwise if you have any other suggestions for another board, or an efficient way for a beginner to do so, I'll take it.

Thank you very much for your attention!
 

Bluejets

Oct 5, 2014
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Most here are English speaking so perhaps find a site to link to that is the same.
 

Harald Kapp

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This module may well work a expected. It seems to consist of an oscillator to generate an AC voltage from the DC input, a small transformer and a voltage multiplier to step up the voltage.
There's no information on the max. output current you can draw. This converter is probably good for a (very) few mA only.
Note that the description contains a disclaimer "de huidige output van de hoge belasting niet worden gegarandeerd op alle tijden" which I read as "there's no guarantee that the initial output voltage will be delivered in the long term".

Note that 400 V is a very dangerous voltage level, even with current being small. Always ensure that the required safety measures are in place. Having a second person nect to you who can interrupt power and give 1st aid in case of an acident is imho a good idea.
 

dorke

Jun 20, 2015
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Here is another option(adjustable).
Have no idea if it is any good.
Do you have the datasheet of the tube in English,especially the current ?
 

kellys_eye

Jun 25, 2010
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Do you think it may be a scam?
No, it's unlikely to be a scam.

AliExpress operate an 'escrow' payment system such that if you find the product to be defective you WILL be refunded. All you have to do is report the fact the item is dud.

The board looks to me to have a simple oscillator and multi-stage rectifier arrangement that equates with their claim for a 400(ish) volts output. It's shown to require some 40mA at 5V which equates to 200mW so the output, assuming a measly 50% efficiency, will be some 250μA at 400V - should be OK for some of the smaller geiger tubes.

You can purchase that board and expect it to work as stated OR you could build a discrete circuit from the many Google-able examples that exist (single transistor, multivibrator etc).

Personally I'd get that board.
 
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Xobtah

Oct 16, 2017
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kellys_eye

Jun 25, 2010
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Yes you need DC but the idea is to use a transformer to multiply the AC upwards (using it in reverse) then feeding the resultant high voltage AC into a multi-stage rectifier ciruit (multiplier) where you end up with high voltage DC.

For example - use a 240V - 6V transformer in reverse ad put a 6V AC signal into it you get 240V AC out of it. Rectify the 240V and DOUBLE it (using a doubler/rectifier circuit) and end up with 500V+ DC coming out of it.

The circuit board you linked to is far more elegant, lower power consumption and a lot smaller.
 

Xobtah

Oct 16, 2017
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Cool! The only thing is that I plan to use an Arduino for that, so I start with 5V DC. But then, I have to get a 5 to ~200V transformer that may output AC voltage, and feed it into a doubler that outputs ~400V DC. Simple enough, I guess. Do you have advices for the components I can buy?
 

davenn

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The board you linked to in your first post is the best way to go.

agreed

have fun and let us know how you get on
I look forward to seeing an update or so in this thread

do you already have some radioactive materials to test it with ?

My own Geiger counter is also a pretty basic one, I built it from a kit ~ 25 yrs ago
Have a lot of "HOT" rock samples that drive the counter nutz. Some are much more radioactive than others
there isn't any meter or data-logging, just a speaker that you can hear the clicks :)
I was at a rock and mineral show about a month ago and added around 6 new samples to the collection

One day I mite improve on the system

a lot of the older home smoke detectors have a radioactive source in them ... a tiny bit of Americium-241
they will make a counter click happily :)


Dave

Edit ...
ohhh ... for your interest, these counters mostly detect gamma particles (rays)

alpha particles = helium nucleus = 2 protons and 2 neutrons
They generally don't travel far, a few inches or so as they will take up free electrons easily and become stable helium atoms. a thin sheet of paper will stop them

beta particles = hi speed electrons/positrons, they are emitted by an atomic nucleus. a thin sheet of aluminium will stop them

gamma particles(rays) = are electromagnetic radiation aka high energy photons and like beta particles are emitted by a decaying atomic nucleus. They require substantial shielding to stop their transmission ... lots of lead etc
 
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dorke

Jun 20, 2015
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Well,
This should be called a "Geiger detector" to make a counter you actually need to count...
And there is the possibility to add the ability to know the "strength" of the radiation.
You can make it a "Geiger radiation intensity detector and counter".
 
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Xobtah

Oct 16, 2017
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do you already have some radioactive materials to test it with ?
Not really, I've planned to have long walks in nature to see if there is some reaction, otherwise I found uranium glass for test purposes for something like 6$. Plus I like radioactive stuff, so it would be a good piece for collection anyway.

ohhh ... for your interest, these counters mostly detect gamma particles (rays)
Yes I'm aware of that, but as long as I get a reaction, I'm going to be very happy, I don't plan to use it for very accurate scientific measures :p

This should be called a "Gieger detector" to make a counter you actually need to count...
I'm going to plug my arduino in in order to count, I have a LCD screen that's going to be used to display the CPM and absorbed dose.

I'm going to make a schematic in order to have a clear idea of what I need to in as soon as I get my board, could you tell me whether it is viable or not?

Thank you all for your answers, I've already learned a lot from this conversation.
 

KMoffett

Jan 21, 2009
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Your or dorke's boards are very good choices. If you are interested in building your own, I did a simple one with a 555 timer. If you just want 400VDC, remove of the one of the doubler stages.

Ken
800VHVPS02.gif
 

Xobtah

Oct 16, 2017
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Hi guys!

I ordered the board and I'm waiting for it.
While waiting, I tried to make the KMoffett's schematic on Fritzing in order to know if I everything's clear (even if I don't understand everything). Here it is.
(The Geiger tube will fit in serie next to the 6th capacitor)

I also have a question: knowing that the board I ordered has 4 terminals: two for 5V input & GND, and two for 400V & GND, can I connect my arduino directly on the board? I mean, does the GND to GND connection inside the board makes the voltage decrease from 400 to "normal arduino" volts?
Because if so, I only have to connect the arduino 5V output to the board's 5V input, arduino's GND to the board's GND (the one next to the 5V input), and then connect the tube's two terminals on the other side of the board, and count for the amount of time the circuit closes per minutes, quite simple, 3 components, am I right?
 

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NMNeil

Oct 3, 2014
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I'm new to electronics and still learning but have a concern from your schematic that the inductive 'kick' from L1 when Q1 turns off may cause overvoltage problems with the Arduino.
 

duke37

Jan 9, 2011
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I'm new to electronics and still learning but have a concern from your schematic that the inductive 'kick' from L1 when Q1 turns off may cause overvoltage problems with the Arduino.
I agree with this. I assume the Arduino is providing 5V for the power supply. A capacitor cross this supply would help. Better to use a separate supply for the power supply.

The diagram would be much easier to read if you had a straight horizontal ground connection at the bottom of the page and a 5V line towards the top of the page.

I see no feedback to control the high voltage at a set level.
 

Xobtah

Oct 16, 2017
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Hi guys!

I've just received the voltage booster and made a little "sketched" circuit to show you the way I was thinking the project. I'm going to link you the pic I took.

I also asked my computer science teacher his thoughts about it, he told me about the separate supply, so I'm going to try to make a decent schematic to make it clear before I put actual electricity in it.20171108_132053.jpg
 
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