Static Electricity Detector (Easy to make)...

12/13/2011

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:

The first link is here. Second link here. Enjoy!!!

81 Comments

Lewis

12/7/2012 06:57:11 am

hi the cuircit with the fet trasiter is great i have mde thousands.

Greg link

2/19/2013 05:52:34 pm

Hi Ken,
Could you tell me if the FET that you used picks up negative or positive static charge? Also, what is the type of FET needed to pick up the opposite charge? I guess a simpler question would be, what are the separate FETs that I would need to indicate a 1- negative charge and 2- a positive charge? Thanks!

Ken

2/20/2013 08:18:02 am

Hi Greg,
The FET used in this project will detect bot positive and negative charges. In the example shown the FET dims and turns off with a negative charge, but with a positive charge the LED will get brighter. The problem is that it is difficult to see. But, you could try to add a low value resistor on the plus side of the circuit to reduce the current and brightness of the LED and then use a positive charge to brighten. I have not done this but it should be workable. You could also play with the voltage to the FET. Try various materials from the triboelectric series. I have added a link to the Wikipedia entry and the series is listed on the right side. Teflon is a good material to try for your experiment. Good luck, Ken. http://en.wikipedia.org/wiki/Triboelectric_effect.

Greg link

3/3/2013 12:25:54 am

Would a FET 2N5460 work to detect positive?

christophe link

1/24/2016 06:34:09 am

can you pls tell me presisely the number of the fet

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!

Mohammed link

5/17/2013 02:42:31 am

Hi would a nchannel p14nf10 mosfet work. And I want it to do the opposite so would I have to wire the circuit the other way around with a resistor to limit the voltage and current in the mosfet.

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)

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.

mohammed ahmed

5/22/2013 10:23:05 am

what mosfet are you using in this project.

Greg link

5/20/2013 05:11:09 am

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!!!

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.

Ken

10/15/2013 02:01:01 am

Hi Brett,
I believe that the premise about string moving would provide static electricity potential may not be valid. Since the triboelectric effect depends on dissimilar materials shedding electrons, the conditions for static electricity would not be met. However, if you were to coat the gate with a polymer insulator and moved the string quickly, it might be possible to see the effect. But, the big variable is the humidity. The effect of moisture has a direct impact of increasing/decreasing sensitivity. But, let me know if you are able to make this idea works. It is interesting. Thanks, Ken.

Mark

12/2/2013 11:37:11 pm

Followed your guide and it works.

Any chance you can tell me how i could make one which detects positive not negative i have just got some 2N5461 transistors which are p channel and have the gate,source & drain in same place

hope you can help and thanks for such easy to follow guide.

Ken

12/3/2013 07:32:06 am

Hi Mark,
I suggest that you read the comments from Greg and my thoughts in those replies. Since then, I have done some research and one of the problems is that when the detector sees positive it is just barely visible. Also, the detection is based on net charge and most materials have both positive and negative charges. You could try an insulated antenna and play with the length to change sensitivity and polarity. It is an interesting problem with not always clear answers. Thanks for the question and comment, Ken.

Lazar

12/29/2013 11:56:10 am

thanxx ken.....it was very useful

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

Ken

3/19/2014 01:34:47 am

Hi Jay,
There are several ways to sound an alarm with this circuit. I was thinking about a 3 volt relay but the coil current may be too high and the FET would be unable to trigger it. I think that the easiest would be to use an NPN 2N2222 as a switch. There are many circuits on the web so a search would be in order. Thanks, Ken.

Noob

3/26/2018 11:08:16 am

yeet

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?

Ken

3/26/2014 08:38:57 am

Hey Mark,
I am not quite sure I understand the application as the body can be charged, but not radiate a charge. Are you saying that with just your finger being near the FET you get the LED to dim?

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,
Sorry about the long delay but the concept of charge detection is not as easy as it might seem. I have been looking around and finally found a circuit that that solves your question. It is a circuit that uses three gates of a 4011 nand cmos. It looks interesting and I have included a link to copy and paste. I also have a rough diagram found elsewhere if you are interested. I have not built it as yet but probably will this winter. If you want the rough pictorial send me an email. ken.quast@gmail.com. Here is the link:
http://www.ece.rochester.edu/~jones/demos/ahern.html

jay

3/26/2014 08:19:59 am

Hey Ken thanks for last reply.
i managed to make the sensor but for some reason my LED light burned out with 5seconds. I tried it again with another led and same thing. Any ideas?

Ken

3/26/2014 08:47:08 am

Jay,
There are a couple of possibilities. If the wiring is correct it should be current limited by the FET. But, it sounds like either there is too much forward voltage or forward current going to the LED. Without the LED in the circuit, use a multimeter and check the voltage. If it exceeds 2.5 or 3 volts that will burn out the LED. Then check the current and it should be about 20 milliamps. If everything is OK I would suspect the FET as bad. Thanks, Ken.

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??

Ken

7/26/2014 09:13:58 am

Hi David,
Yes it is possible but with the FET there are some uncertainties. Read some of the comments where we have discussed the problems. My best suggestion is the use of a 4011 CMOS nand chip. The circuit is a bit rough but should be easy to build. I provided this link for Mark above to copy and paste to consider. I will probably try to build it as time allows. Here is the link: http://www.ece.rochester.edu/~jones/demos/ahern.html
Good luck and stay in touch. Ken.

ankita mallick

1/31/2015 04:01:50 pm

can i use mosfet? if yes which type then.

Ken

2/1/2015 12:43:55 am

Hello Ankita,
To begin with, the MOSFET is a special type of FET whose Gate is insulated from the main current carrying channel. It is also called the IGFET or the Insulated Gate Field Effect Transistor. A very thin layer of silicon dioxide or similar separates the Gate electrode and this can be thought of as a capacitor. The insulation makes the input impedance of the MOSFET even higher than that of a FET. The working of the MOSFET is very similar to the FET. Having said that, it is possible to use a MOSFET but the gate isolation might be more difficult to design with easily. I would stick with the FET unless you have a specific need for a higher power MOSFET. Ken.

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.

Ken

2/21/2015 01:53:44 am

Hi Clive,
Because the circuit is so simple, almost and field effect transistor will work.For example in the UK the MPF102 would be a good choice. But any will work. The LED is any 5 mm type available there as well. Thanks, Ken.

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/

raju link

3/6/2015 05:08:02 pm

with out battry use led

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

Ken

4/8/2015 08:05:33 am

Hey Keenan,
If it is built as in the diagram it will detect a static charge that is dependent on the humidity. The drier the air the more charge is available as moisture reduces charge potential.

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

Ken

10/8/2015 09:34:55 am

Hey Rick,
This P-Channel enhancement mode power MOSFET has an inherent feature that makes it less suitable for static detection. The gate is insulated from the P channel and has extremely high resistance. So, to overcome the resistance the power has to be higher. You may want to re-think the use of power Mosfets and go to the lower power FET. But your use of the UV LED did give me an idea that could be interesting. In the circuit that I used the positive static charge causes the LED to glow but to low to see. If you enclosed the UV LED in a container with fluorescent dye removed from a Sharpie Hi lighter, (If you search Neon on my site I have the process), the low power light might be visible. Just a thought. Of course you may also want to consider the use of the old CMOS 4011, which uses only three of the four gates. Copy and paste here: http://www.ece.rochester.edu/~jones/demos/ahern.html. Best of luck, Ken.

Rick link

10/8/2015 10:20:41 am

Here is a link for the video of the n-channel in action... i am trying to make separate devices for each channel for my application i don't want them in the same box... and i have seen video's of these both being used and working... i am just missing something

Ken

1/24/2016 08:37:54 am

Cristophe,
It is a MPF102 Field-Effect Transistor N-Channel. Ken

David Sr. link

3/4/2016 01:29:55 am

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.

mahendra devare

9/25/2016 08:44:36 pm

Please send me circuit diagram & video

Mahendra devare

9/27/2016 06:35:59 pm

Sir how it will be work
When the static change present in our body so red led glow & static charge discharge on that time red led off & green led glow. Green led indicat static charge not present in our body.
The circuit work this type function.

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.

Dave Sr. link

3/4/2016 11:37:40 am

Here is the video. Sorry about the quality.
http://www.youtube.com/watch?v=5F3ZjZIU2qU

Dave Sr.

3/4/2016 01:11:01 pm

Here is the schematic diagram for the device.
http://www.youtube.com/watch?v=FYNipg1j3IQ
The resistor values are not critical. The 1 Meg resistors can be replaced with 2n4148 diodes if you are having self-oscillation issues. Experiment with it and good luck.

rayaan

3/12/2016 12:15:22 am

which transistor should we use

Ken

3/12/2016 09:30:39 am

Rayaan,
I used a MPF102 but a 2N3819 will work as well. They may be easier to find on Ebay as Radio shack has limited stock. But, you can do a search for any N channel FET and compare as a substitute. Ken.

David

3/12/2016 04:14:55 am

I unsubscribed by mistake so I had to post this to resubscribe. ;)

Jency link

5/2/2016 12:08:20 am

This is the good news, charging current will be saved in winter.

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 ?

Ken

7/11/2016 05:30:05 pm

Chui Sin Min,
No, I have not measured the range as I really do not have the equipment to accurately measure triboelectric charge, The big problem is that the range changes with the dryness of the air. So, depending on the humidity as mentioned in the write up changes, so does the range. It is an interesting problem and maybe I have to try to accomplish some form of measurement. Thanks for the comment and question, Ken.

Chui Sin Min

9/27/2016 10:51:45 pm

Thank you for your comment.

Marcus Gardner link

7/15/2016 10:46:48 am

Hi Ken,

I'm an electronics moron!
How do I connect the resistor to the positive? If you could add it to the image at the top of the page and send it I'd be grateful.

Ken

7/15/2016 04:47:58 pm

Hi Marcus,
There is no resistor in the original detector so I am assuming that you want to limit the current to the LED. If you look at the photo at the top of the page the resistor will go between the drain and the positive leg of the LED. Simply break the connection between the drain and the LED and add the resistor. If I made an incorrect assumption let me know. Thanks, Ken.

Victor Wedel link

3/17/2017 08:13:09 pm

Hello Ken,
I have a non-profit org whereby I help the homeless. I have an idea that I would like to ask and to see if you could help me with this...
Thank you very much,
Victor

David M.

3/17/2017 08:25:21 pm

Email address update... ;)

Vann

8/26/2017 12:49:32 pm

How can i find FET? Pls help me?

Ken

8/26/2017 04:05:58 pm

Vann,
Digikey, Jameco, or Ebay would be sources. Ebay may be best as it probably has free shipping. Ken.

David M.

8/26/2017 05:13:56 pm

Here is a direct link to the FET you need Vann:
http://www.ebay.com/itm/5PCS-MPF102-MPF102G-TO-92-FAIRCHILD-Transistor-/302410509027?hash=item4669122ae3:g:kdkAAOSwbtVZUx5T

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.

Ken

10/10/2017 10:25:07 am

Hey Mike,
The plastic box should be fine as it is an insulator unless you charge it with wool or other material. If you want to be certain you could run a dryer sheet (Bounce or other) over it to dissipate any charge. The antenna lead is already very sensitive and depending on relative humidity, good for at least a meter. Extending the lead might increase the range but may also begin to pick up other RF sources and the LED would remain on. If you make the lead hole large enough you should't need any grommets. Hope that this helps, Ken.

Mike Wabe

10/10/2017 10:37:59 am

Great, many thanks

Victor Wedel

10/10/2017 05:25:11 pm

Hello Mike,
I wanted to ask if you would be interested in doing a prototype for our non-profit org.
Also thank you for sharing your projects too.
Sincerely,
Victor

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.

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....

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.

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.

Ken

11/21/2017 03:49:54 pm

Mike,
Too soon to quit so lets find the problem. First, do you have the correct parts? What are the symptoms of the "not working"? We can fix this! Ken.

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.

ben

2/17/2018 06:38:52 pm

effectiveness of static electricity detector project

TOMS THOMAS link

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?

Ken

6/1/2018 09:29:49 am

Hi Toms,
Ebay has many real Fairchild 102's cheap and some with free shipping. Most MOSFETS are not leaky enough. Ken.
https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2380057.m570.l1311.R1.TR3.TRC1.A0.H1.TRS0&_nkw=mpf102&_sacat=0

Qudor

11/4/2020 11:44:14 pm

Thanks good job
what I concluded from the comments that the author don't know with FET he used :D

Ken

11/5/2020 03:25:23 pm

Qudor,
Because the circuit is so simple, almost and field effect transistor will work.For example in the UK the MPF102 would be a good choice. But any will work. The LED is any 5 mm type available there as well. Thanks, Ken.

Washington Guys link

3/18/2021 01:20:22 am

Thhanks for posting this

David

3/18/2021 07:15:33 pm

I mistakenly unsubscribe...how do I get re-subscribed??? Thanks!

Static Electricity Detector (Easy to make)...

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