
![]() For many people winter is approaching and the temperature is going down. But, it also is a time when the air will hold less moisture, and dry air breeds static electricity. Or, more accurately, dry air does not allow static electricity to dissipate as easily as moist air. So, this seems like a good time to share an easy to make static electricity detector. I have made this circuit many times over the years and it is fun to use and it demonstrates some of the characteristics common to field effect transistors. (FET's). They act as switches and are very sensitive to static charges in the air. In fact, this circuit can detect a negative charge at over 5 feet when the relative humidity is low. There is also an explanation of the triboelectric series in the attached links.There are only two parts needed and they are available at Radio Shack as well as most electronic suppliers. The first is the FET, Radio Shack #276-2062, and a red light emitting diode, (LED) #276-041. And it is powered by a 9 volt battery.The circuit can be soldered, connected with alligator clips, or as shown in the video, a homemade printed circuit board is used. After the video, links will be provided with really excellent explanations and use of the detector. Also some explanatory photos:
81 Comments
Lewis
12/7/2012 06:57:11 am
hi the cuircit with the fet trasiter is great i have mde thousands.
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Hi Ken,
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Ken
2/20/2013 08:18:02 am
Hi Greg,
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Sean
8/30/2017 01:04:52 am
what FET was used and is there an equivalent that is used in South Africa
Ken
3/3/2013 01:52:15 am
Since that is a P channel JFET, it might be a good choice. To switch off an n-channel device requires a negative gate-source voltage (VGS). Conversely, to switch off a p-channel device requires positive VGS. Give it a try and let us know. Good idea Greg!
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Ken
5/17/2013 02:57:47 am
Yes, it will work but I am not sure of the voltage or current to make the switch. But, I would try 9 VDC with a small value resistor to the source. Perhaps even a trimmer in the 1K range. Ken.
mohammed
5/19/2013 10:06:14 pm
perhaps i could try a 330ohm resistor feeding into the mosfet then connect the mosfet to the led. the arrangement would be (negative to resistor to drain, source to negative leg of led, positive led leg to positve part of the battery)
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Ken
5/20/2013 01:55:43 am
Sounds possible but only if it is a three lead Mosfet. In this case the body is internally connected to the source. If it is a 4 lead device, I would connect the body to the source. Also, I am not sure about the resistor value but it sounds as if you have a good idea based on the Mosfet type. Let us know how it works. Ken.
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mohammed ahmed
5/22/2013 10:23:05 am
what mosfet are you using in this project. Thanks for all of the replies people. Much appreciated! However I am a complete idiot when it comes to electronics. Plugging in the toaster is a major achievement for me so the more complicated this gets the more lost I become. I'll stick with Ken's original advise regarding the (3 lead) fet 2n5460. Thanks again!!!
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Brett
10/15/2013 12:09:06 am
Is there a way to adjust the sensitivity of this circuit? I'm wondering if it would be able to detect a movement of a string across it? If the string is moving I would assume that a static charge would be created. If it remains still it should have no potential. I would like to power it from 24VDC and switch a relay. Could use an optoisolator on the output.
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Ken
10/15/2013 02:01:01 am
Hi Brett,
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Mark
12/2/2013 11:37:11 pm
Followed your guide and it works.
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Ken
12/3/2013 07:32:06 am
Hi Mark,
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Lazar
12/29/2013 11:56:10 am
thanxx ken.....it was very useful
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Jay
3/18/2014 10:36:31 pm
hey ken do you think we could add an alarm aswell as the led so it would make noise when it detects thanks ... jay
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Ken
3/19/2014 01:34:47 am
Hi Jay,
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Noob
3/26/2018 11:08:16 am
yeet
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Mark Manjo
3/25/2014 03:48:45 pm
I am making a static detector. im using a mpf102 transistor and a LED and a four battery pack that includes 4 1.5V batteries (AA batteries). everything works well. the LED turns on and it dims when my finger gets near it. BUT...I want to reverse the outcome. I want the LED to turn on when my fingers get near it. How can I do that?
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Ken
3/26/2014 08:38:57 am
Hey Mark,
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Mark
3/31/2014 06:48:47 am
yes that's exactly what I am saying but, I want it to turn on when my finger gets near the FET. How do I do that?
Ken
6/23/2014 08:44:00 am
Hi Mark,
jay
3/26/2014 08:19:59 am
Hey Ken thanks for last reply.
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Ken
3/26/2014 08:47:08 am
Jay,
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David Mayer
7/25/2014 05:09:55 pm
Can a detector be made so the LED comes on in the presence of a static field instead of going off??
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Ken
7/26/2014 09:13:58 am
Hi David,
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ankita mallick
1/31/2015 04:01:50 pm
can i use mosfet? if yes which type then.
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Ken
2/1/2015 12:43:55 am
Hello Ankita,
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clive
2/19/2015 11:51:32 pm
Would love to build this but been in the UK we do not have radio shacks to I am hoping that you can let me have the value of the parts used so I can obtain them in the UK.
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Ken
2/21/2015 01:53:44 am
Hi Clive,
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David
2/21/2015 09:59:15 am
You might want to put a 220ohm resistor in series with the LED. I burned my first ultra-bright red LED using this circuit. The resistor limits the maximum amount current that can flow through the LED. I built my detector on a small PCB super glued to a 9V battery connector. You can see my detector here: http://www.instructables.com/id/Static-Electricity-Detector/
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Keenan
4/7/2015 02:27:47 pm
is there some thing it detects best with or dose it depend on how you build it
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Ken
4/8/2015 08:05:33 am
Hey Keenan,
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Rick
10/7/2015 11:51:41 am
i have been searching almost every forum i come across about these ... and no one gives straight answers. I have made N-channel detectors using a IRF730 fet, a 3.5v UV led (had them laying around) powered by a 9v battery but in order to not burn the led out i had to add a 4.7m ohm resistor to the ant. and this set up works great rub some plastic on your hair and put it near the ant and the light goes out.. now i am also trying to make a positive channel detector with a FQP27P06 but i can not seem to get this circuit to work at all. i have tried many different values of resistors ... i cant even burn out a led with it if i try... do you have to connect it differently than the n channel? any thoughts would help ... ty
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Ken
10/8/2015 09:34:55 am
Hey Rick,
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Ken
1/24/2016 08:37:54 am
Cristophe,
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Dealing with the frustration of having the led get dim when detecting a negative charge, I designed a circuit that uses two mpf102's, one 2n4401, one 2n4403, one green led, one red led, two 1k ohm resistors, two 100 ohm resisters, two 2n4148 diodes, a 9 volt battery, switch and a small meter from a donor cb radio. The green led lights in the presence of positive static charges, and the red led lights in the presence of negative static charges. The meter has a corresponding red/green face. I will make a video showing it in action.
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mahendra devare
9/25/2016 08:44:36 pm
Please send me circuit diagram & video
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Mahendra devare
9/27/2016 06:35:59 pm
Sir how it will be work
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Mark
3/4/2016 02:39:52 am
David Sr be good if you could give a diagram of the circuit that you have done i managed to make a negative and positive but only they get dim be good other way round and your circuit sounds like it does that.
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Dave Sr.
3/4/2016 01:11:01 pm
Here is the schematic diagram for the device.
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rayaan
3/12/2016 12:15:22 am
which transistor should we use
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Ken
3/12/2016 09:30:39 am
Rayaan,
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David
3/12/2016 04:14:55 am
I unsubscribed by mistake so I had to post this to resubscribe. ;)
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Chui Sin Min
7/11/2016 01:40:13 am
Mr. Ken, Hope you are well. I am Chui from Singapore, thank you for sharing the idea. Just one question, you have ever measure the static charge ranges the unit can detect ?
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Ken
7/11/2016 05:30:05 pm
Chui Sin Min,
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Chui Sin Min
9/27/2016 10:51:45 pm
Thank you for your comment. 7/15/2016 10:46:48 am
Hi Ken,
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Ken
7/15/2016 04:47:58 pm
Hi Marcus,
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3/17/2017 08:13:09 pm
Hello Ken,
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David M.
3/17/2017 08:25:21 pm
Email address update... ;)
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Vann
8/26/2017 12:49:32 pm
How can i find FET? Pls help me?
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Ken
8/26/2017 04:05:58 pm
Vann,
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David M.
8/26/2017 05:13:56 pm
Here is a direct link to the FET you need Vann:
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Mike Wabe
10/8/2017 01:40:59 am
With the bent gate leg used as an antenna, will this still work OK in a plastic enclosure box? Would it get a better signal/be more sensitive if the antenna leg was lengthened, by using a piece of copper wire such as the earth wire in the cable that is used in houses to link electric plug sockets? If this is the case, what would be the optimum length of the extension? Lastly (you can breathe a sigh of relief now!), if using the antenna extension, would the hole in the enclosure box need to be earthed using a rubber grommet (or similar) to prevent it touching the plastic enclosure box which might itself be subject to static? Many thanks for your time.
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Ken
10/10/2017 10:25:07 am
Hey Mike,
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Mike Wabe
10/10/2017 10:37:59 am
Great, many thanks
Victor Wedel
10/10/2017 05:25:11 pm
Hello Mike,
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Mike Wabe
10/11/2017 03:22:18 am
I am by no means an expert and I will be using this device during paranormal investigations. I will happily photograph and describe the build, and add comments about its operation as time goes by, if you would like me too.
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Victor Wedel
10/11/2017 10:51:43 pm
Thanks Mike I appreciate that and can make this too as I see there are places to get these parts....
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Mike Wabe
10/11/2017 11:50:01 pm
I got the parts from eBay and Amazon. They should arrive soon. I will photograph and describe the build and post here when I have done so.
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Mike Wabe
11/21/2017 01:11:27 pm
I've had 3 goes at making this now and none have worked. Sadly I have decided to give up.
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Ken
11/21/2017 03:49:54 pm
Mike,
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Mike Wabe
11/21/2017 11:04:37 pm
The circuit is simple and the parts are exactly as prescribed above. I connected them just as described. But no amount of static electricity makes anything happen. As I said, i’ve built it 3 times now, and none work. I’ve now run out of components and it is not my intention to buy more.
David
11/21/2017 11:47:29 pm
Perhaps "static" is destroying your FET's???? Are you and your work area grounded???
Brad
11/27/2017 12:08:15 pm
Mine are not working either. How are you testing? If I ground the gate, the led goes off, but I need a very hard gate. I think they are using a different part than the MPF102.
Mike Wabe
11/27/2017 01:03:54 pm
I know what you mean about grounding, but the answer is no I didn't ground myself. Having said that, I am standing on a concrete floor and the workbench is wood. The FETs are kept in the static-proof pouch they arrived in until I used them.
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ben
2/17/2018 06:38:52 pm
effectiveness of static electricity detector project
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6/1/2018 12:52:35 am
Are there any substitutes for the FET mentioned in your design? The MPF102 is becoming hard to come by. Would a MOSFET be an effective substitute? Are there any commonly available replacements or old household devices which use FETs?
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Ken
6/1/2018 09:29:49 am
Hi Toms,
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Qudor
11/4/2020 11:44:14 pm
Thanks good job
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Ken
11/5/2020 03:25:23 pm
Qudor,
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David
3/18/2021 07:15:33 pm
I mistakenly unsubscribe...how do I get re-subscribed??? Thanks!
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AuthorThe author has an eclectic background in chemistry, electronics, writing, mental health, and community action...Ken Archives
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