Help to build a Ion Detector, please....

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Cyrano
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Help to build a Ion Detector, please....

Post by Cyrano » Sun Jan 10, 2010 7:27 am

Hi People!...
I have decided to build a ion detector circuit I have found on a book.I'm not an electronic engineer, so I want to see if there is some people so gentle that can help me to make this project.Essentially, the circuit is the same posted here:http://www.sentex.net/~mec1995/circ/hv/ ... ondet.html
except for the first stage were the ions are collected.The text says that the schematic configuration allow you to detect negative ions from the air ,and reversing the polarity of the transistors you can detect also positive ions.The book suggests to implement a DPDT Switch to reverse the detection.But I don know at were point of the schematic apply the switch....

As panel meter the article says to use a 100 Milliamps model;instead the book says 100 Microamps. Maybe there is a error in the text.I have the 100 Milliamps model with an internal resistance of about 1,9 Ohms,but at this point,I dont know what are the correct value resistors to use in the circuit.

Any suggestions? Thank you.

Cyrano

k7elp60
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Re: Help to build a Ion Detector, please....

Post by k7elp60 » Sun Jan 10, 2010 8:10 am

Looking at the schematic I see a number of issues. 1. The PN2222 is drawn as a PNP when in fact the PN2222 is a NPN transistor. 2. The Polarity of the battery for the PN2907 transistors is incorrect. There is no current limiting resistor for the LED.
Aside from this I would use the 100 microamp meter, but I would put a resistor in series with one lead. I would probably start with a 10K ohm.

Cyrano
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Re: Help to build a Ion Detector, please....

Post by Cyrano » Sun Jan 10, 2010 9:50 am

If I add other three transistor with the polarity reversed ,in a parallel path on the circuit ,have you any idea were to connect the DPDT switch to change the sensing of ions?
Q3 have to be reversed,also?

k7elp60
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Re: Help to build a Ion Detector, please....

Post by k7elp60 » Sun Jan 10, 2010 3:19 pm

Cyrano wrote:If I add other three transistor with the polarity reversed ,in a parallel path on the circuit ,have you any idea were to connect the DPDT switch to change the sensing of ions?
Q3 have to be reversed,also?
IF you are asking me, I am afraid I can't help you with the connections of the DPDT switch. If the polarity of the battery is reversed the circuit my work okey, but without a resistor in series with the LED may cause some problems.

sghioto
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Re: Help to build a Ion Detector, please....

Post by sghioto » Sun Jan 10, 2010 6:23 pm

The LED series resistor is the 10K and 5K pot combination. I redrew the circuit below and believe this is the correct orientation using a DPDT switch. Note the common connection on the LED anode.

Steve G.

Image

Cyrano
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Re: Help to build a Ion Detector, please....

Post by Cyrano » Mon Jan 11, 2010 1:15 am

Steve, you are G R E AT !
Thanks for all.I will post the resuts plus the pics of my work.
Best Regards,
Cyrano

jimmy101
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Re: Help to build a Ion Detector, please....

Post by jimmy101 » Mon Jan 11, 2010 10:43 pm

To reverse the polarity of the detector couldn't you just ground the antenna and make the old ground conection the new antenna? Would that would flip the detector from a negative ion to postive ion detector?


What is the detector going to be used for? Detect the negative ions from an air cleaner type ion source? As a generic ion detector? As a radiation detector? As an electric field detector?

There are a couple of extremely simple circuits for ion detection. For electric fields caused by static electricity all you need is an nFET, 9V battery and an LED. For example, RIDICULOUSLY SENSITIVE ELECTRIC CHARGE DETECTOR. Wouldn't be too difficult to add a meter to the setup. I would think it would work with an air cleaner type ion source.

If you want to detect ionizing radiation then there are a couple of simple FET based circuits that'll do it.

jimmy101
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Re: Help to build a Ion Detector, please....

Post by jimmy101 » Sat Aug 28, 2010 11:24 am

http://www.techlib.com/science/ion.html
http://www.sciencebuddies.org/science-f ... p064.shtml

If you want a Geiger Counter type setup then check Ebay. You can usually find simple (cheap) Russian made counters that use a tiny Geiger-Muller tube for about $20. You can also often find surplus civil defense Geiger Counters for perhaps $50.

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