• Skip to main content
  • Skip to primary sidebar

Homemade Circuit Projects

Get free circuit help 24/7

Circuits for Beginners | Basic Circuits | LED Driver | Hobby Circuits | Transistor Circuits

New-Projects | Privacy Policy | About us | Contact | Disclaimer | Copyright | Videos

You are here: Home / Home Electrical Circuits / AC 220V/120V Mains Surge Protector Circuits

AC 220V/120V Mains Surge Protector Circuits

Last Updated on March 16, 2022 by Swagatam 136 Comments

ask questions through comments

Voltage spikes  can sometimes be a big nuisance as far as the safety of the various electronic appliances are concerned. Let's learn how to make a simple AC Mains surge protector circuits at home.

What is a Surge Protector

A surge protector is an electrical device which is designed to neutralize minor electrical spikes and transients that normally keep appearing in the mains utility lines. These are normally installed in sensitive and vulnerable electronic equipment to prevent them from getting damaged due to these sudden unprecedented surges and voltage fluctuations.

They work by instantaneously short circuiting any excess high voltage that may appear in the mains AC line for a very duration.

This duration is usually lasts in microseconds. Anything above this period of time may cause the surge suppressor itself to burn or get damaged

What is Voltage In Rush

A sudden voltage spike is basically a sharp rise in the voltage lasting not more than a few milliseconds but enough to cause damage to our precious equipment almost instantly.

It thus becomes imperative to stop or block these from entering vulnerable electronic gadgets like our personal computers.

Commercial spike busters are though available pretty easily and cheaply too, cannot be trusted and moreover have no reliability test arrangement so it becomes just a "assuming" game, until it's all over.

Working Design

The circuit of a Simple AC Mains Surge Protector Device below, which shows how to make a simple homemade AC mains high current protector device is based on very simple principle of "speed breaking" the initial jolt through components who are well equipped in the field.

A simple iron resistor and MOV combination are more than enough to provide the protections we are looking for.

Here R1 and R2 are 5 turns of iron wire (0.2mm thick) over a 1 inch diameter air core each followed by an appropriately rated varistor or an MOV connected across them to become a full fledged spike protector system.

Sudden high AC entering the input of spike  are effectively tackled and the "sting" absorbed in the course by the relevant parts and a safe and clean mains is allowed to go through the connected load.

Metal Oxide Varistor (MOV) Calculations and Formulas

The calculation of energy during application of such a pulse is given by the formula:

E = (Vpeak x I peak) x t2 x K
where:
Ipeak = peak current
Vpeak = voltage at peak current
β = given for I = ½ x Ipeak to Ipeak
K is a constant depending on t2, when t1 is 8 μs to 10 μs
A low value of β corresponds to a low value of Vpeak and then to a low value of E.

Transient Protector Using Inductors and MOV

inductor MOV based surge suppressor

Question Regarding Surge Prevention in Electronic Ballast

Hi swagtam, I found your email address from your blog. I really need yr help. Actually my company has customer in china we make UV lamps and we use electronic ballast for it. now the problem is in china because of Over Voltage the ballast burn out so i design circuit which is in attachment which doesn't help either?

so i found your Ultimate High/Low Voltage Protector Circuit which i wants to build. or can you tell me the update if i can do in my circuit that will be great. sorry if i am bothring you. but i really really need yr help to save my job thanks Thank You Krishna Shah

Solution

Hi Krishna, According to me the problem may not be with the voltage fluctuations, rather it's because of the sudden voltage surges that's blowing of your ballast circuit. The diagram shown by you may not prove very effective, because it does not incorporate a resistor or any kind of barrier with the MOVs. You may try the following circuit, introduce it at the entry point of the ballast circuit.

Hope it works:

 

Using an NTC and MOV

The following image shows how two different sudden high voltage suppressor devices could be tied up with the mains line for achieving a double edged safety.

The NTC here enables an initial switch ON current in rush protection by offering a higher resistance due to its initial lower temperature, but in the course of this action its temperature begins increasing and it begins allowing more current for the appliance until a normal working conditions achieved.

The MOV on the other hand complements the NTC output and makes sure that in case the NTC is unable to stop the up-surge onslaught correctly, it switches ON itself shorting the residual high transient content to ground and as a result establishing a safest possible supply for the connected load or the appliance.

RFI Line Filter and Surge Suppression Circuit

If you are looking for a mains AC line filter circuit having a combined protection against radio frequency interference (RFI) suppression, along with voltage surge control, then the following design could prove quite handy.

RFI line filter circuit with surge suppression

As we can see, the input side is protected with an NTC and MOV. The MOV grounds any instantaneous over voltage surge, while the NTC limits an over current surge.

The next stage constitutes an RFI line filter, comprising of a small ferrite transformer and a few capacitors. The transformer arrests and blocks the passage of any incoming or outgoing RFI across the line, while the capacitor network reinforces the effect by grounding the residual high frequency content across the line.

The transformer is built over a small ferrite rod, having two identical winding wrapped one over the other, and one of the winding end connections swapped between the input/output Neutral line.

get free help for circuit diagrams

You'll also like:

  • 1.  110 V to 310 V Converter Circuit
  • 2.  Surge Arrestor Circuit with Measuring Facility
  • 3.  Neon Lamps – Working and Application Circuits
  • 4.  Solving LDR Controlled LED Emergency Lamp Problem
  • 5.  Transformerless Voltage Stabilizer Circuit
  • 6.  Push Button Fan Regulator Circuit with Display

About Swagatam

I am an electronic engineer (dipIETE ), hobbyist, inventor, schematic/PCB designer, manufacturer. I am also the founder of the website: https://www.homemade-circuits.com/, where I love sharing my innovative circuit ideas and tutorials.
If you have any circuit related query, you may interact through comments, I'll be most happy to help!

Subscribe for the Latest Posts


 

Reader Interactions

Comments

    Have Questions? Please post your comments below for quick replies! Comments should be related to the above artcile Cancel reply

    Your email address will not be published. Required fields are marked *

  1. Daniel says

    April 11, 2022 at 4:15 pm

    HI Swagatam,
    I’m at a revision of a Pinball machine. Either I replace the old bulky LineFilterAssembly or I take it apart and replace the components. This Filter is already 30 years old. It contains a Thermistor to limit the inrush current and a Varistor to protect from over voltage and it contains an EMI Filter. The whole LineFilterAssembly feeds a quite big transformer with 1 primary and 9 secondary. The highest secondary is 100V and the lowest is 9V. The whole machine is fused to 220V 5A T. Do you know a compact device who can handle the requirements? Would you restore the original LineFilterAssembly and replace the onboard components?

    Reply
    • Swagatam says

      April 11, 2022 at 8:38 pm

      Hi Daniel,

      The only EMI filter circuit that I know is the one shown at the end of the above article. You can probably try the last circuit from the above article by building the RFI filter using thick wires, may be 1mm thick.

      Reply
  2. Roopesh Gowda B M says

    March 21, 2022 at 12:48 pm

    Hai Swagatam,
    I am working as a hardware engineer in one of the reputed company, and i am working on a filter.
    Basically we install some electronic equipment’s in central railways and there there is 110VAC, which is regulated from railways 25000V. but when switching happens or power on off happens there is a high voltage surge and that surge is spoiling my LC filter as well, please suggest me a way to solve this issue.
    input= 110VAC
    surge = nearly 4000VAC
    surge duration= 3-4 millisec

    please suggest me a way forward to solve this issue.

    Reply
    • Swagatam says

      March 21, 2022 at 5:23 pm

      Hi Roopesh, I think you must install powerful MOVs at the input side of the AC mains. One such example can be studied in the following article:

      https://www.homemade-circuits.com/high-power-industrial-surge-suppressor/

      Reply
      • KABIR ABDULRAZAK says

        March 30, 2022 at 3:04 pm

        Good morning sir.
        Long time , please I have a question, may I use this circuit to apply it in my arduino circuit to protect my Arduino from EMF . because sometimes my Arduino hocked and stopped working at any time while in working because am using High voltage generator in the circuit.

        Reply
        • Swagatam says

          March 30, 2022 at 4:58 pm

          Hi Kabir, the above circuits are meant for AC mains surge suppression, not for Arduino circuit. For Arduino circuits, you can feed the 12V to the Arduino through a 7812 IC and connect a 1000uF/25V capacitor right across the DC input pins of the Arduino. This will help you to get rid of any kind of interference from the high voltage generator.

          Reply
  3. Chaplin says

    March 16, 2022 at 1:25 pm

    Hi,
    I would like to build an inductor (line reactor) as it was done in the patents used by Zero Surge, Surgex, BrickWall.
    Could you walk us through how to build this type of inductor for overvoltage protection?
    It is a 100mH air inductor in the case of Zero Surge but there are 2 inductors I believe in the case of Surgex which is even more efficient.

    In the case of this circuit, the use of a ferrite would lead to a rapid saturation that is why you propose an iron core in your answers for the protection of overvoltages and not just as a common mode filter?
    In your texts you write ferrites but I think it is rather an iron core (as you have answered to others) since ferrite indicates a mixture of metals… Otherwise, what type of ferrite do you suggest?

    Reply
    • Swagatam says

      March 16, 2022 at 5:49 pm

      Hi, sorry I do not have the exact calculations for building the kind of surge suppressor that you are referring to, so it is difficult for me to suggest anything useful.

      Yes iron core may work better for mains surge suppressor inductors since the frequency range of the input AC is within 50 and 60 Hz.

      Reply
  4. Alberto Flor says

    September 14, 2021 at 6:26 am

    Im interested with your innovations and circuit designs.

    Reply
  5. SAURABH ALTEKAR says

    August 21, 2021 at 1:26 am

    Hello,
    I am Mr. Saurabh from India.
    I request you to suggest me solution for a problem that I am facing
    First I’ll explain you the circumstances and my setup .
    circumstances :-
    In India we normally have 220V to 240V AC Supply.
    But we have some problem in our area , Voltage normal range is 260V to 290V, service provider company is irresponsible, so I am handling it with Servo Stabilizer and reduce it to safe range of 220-240V. But during Night 11:30pm to morning 5.00AM Voltages surges up to 310V and it is beyond my stabilizer range.
    There is an automatic relay controller that cuts main supply if Voltage is more than 300V. Then it monitors voltage for some time, if it is unsafe, main supply remains disconnected permanently ( and then relay is to be reset manually, even if supply goes safe it does not start automatically ) Due to which whole night UPS remains active and battery goes down by 5am.
    Due to 300+ Voltage, when main supply is disconnected by relay, some revers current continues, resulting led and tube lights corners to glow slightly, even if they are switched off !! There is RCCB after Relay, when it is switched off manually led and tube lights corners does not glow.

    Setup:-
    1) First supply comes to Relay range of 145V to 300V, 16AMP upper limit is se
    2) Then, there is 63AMP RCCB for shock protection, current leakage (30mA protection)
    3) Then there is servo stabilizer 3KVA range 145V to 300V
    4) Then there is UPS 1.5KVA
    I want some solution that will reduce extra voltage from 290V to 335V with addition of some circuit.
    Kindly suggest me solution.
    ThanX

    Reply
    • Swagatam says

      August 21, 2021 at 9:23 am

      Hello, the only feasible option is to build another stabilizer circuit which will changeover when the mains voltage reaches 300 V, and will reduce it by 50V, so that 300V now becomes 250V….or 330V is reduced to 280V and so on.

      You can try the concept explained in the following article:

      https://www.homemade-circuits.com/how-to-make-small-homemade-automatic/

      Make sure TR2 is rated at 24-0-24V, 5 amps

      Reply
  6. Ankush Gupta says

    July 4, 2021 at 1:44 pm

    Hi. Thanks for making homemade circuits website. We want to develop 4kv, 6kv and 10kv surge protection device. Need help 🙏

    Reply
    • Swagatam says

      July 4, 2021 at 5:51 pm

      Hi, thank you,

      for 4kv and above you will need a MOV or metal oxide varistors rated to handle the same amount of voltage as specified.

      If you Google “4kv MOV” you will be able to find many online sources selling MOVs rated to handle this power

      Reply
  7. Subir says

    April 26, 2021 at 6:29 pm

    Hi Swagatam,
    Can I add one more NTC at neutral line as well as live line too…is it give better inrush current protection?….Waiting for reply

    Reply
    • Swagatam says

      April 27, 2021 at 9:41 am

      Hi Subir, you can do that but that might increase the effective series resistance in the mains line, and could affect the working performance of the load….

      Reply
  8. Shady amy says

    January 31, 2021 at 6:54 am

    Hi Swag,
    Very nice explanation..thnks for sharing the knowledge…bro can u please guide me..
    I made a extension board with 3 sockets and 3 switches ..1 indicator and 1 fuse…I intend to connect 1 55inch led tv…1 pc…and 1 Playstation can u pls tell me the value of fuse I should use (6amps or 10amps)…and pls tell me the value of mov with its complete part no.
    Incoming voltage is around 220-240v.
    The pc connection is via a digital ups..that means I am connecting the ups to one of the 3 sockets in the extension board.
    The drawing wattage would be around 400 to 700watts if all 3 equipments are on simultaneously.
    And pls tell me the value of thermistor
    Can I add ptc in series with ntc so as to arrest the current surge in addition to rush current protection done by ntc

    Reply
    • Swagatam says

      January 31, 2021 at 6:01 pm

      Hi Shady,
      Since the fuse is supposed to be rated in amps, we have to find the maximum permisible amps to the systems combined. Dividing the 700 watts with 220V gives 3.18 amps, meaning a 3.5 amp fuse would be just enough for the task.

      I won’t suggest a PTC, since an NTC will be itself quite sufficient for controlling the initial switch ON surge. You can use any 4 amp (steady current) NTC for the purpose.
      And instead of PTC, you can employ an MOV rated to tackle 350V peak voltages.

      Reply
      • Shady amy says

        February 1, 2021 at 11:02 pm

        Thnks for the prompt response…salute ur dedication.
        As per your suggestion I will go ahead with the ntc. But the fact is that ntc will clamp the initial switch on current surge..and the threat of overload current flow in some instances still pose a danger
        so to curb all 4 instances like
        1)  voltage surge
        2) voltage overload
        Mov will manage

        3) initial current surge = ntc
        4) current overload = ?
        Pls specify any addon to arrest the overload current
        And I humbly request u to specify the part no.
        Of mov,ntc,and new addon if any(overload current protection)
        For example 20d471 mov or any other
        Thnks again.

        Reply
        • Swagatam says

          February 3, 2021 at 1:26 pm

          You are welcome! The overload current can be controlled by the fuse itself! An additional circuit can be use to shut of a relay, as discussed
          in the following diagram:

          Mains AC Overload protection Circuit for Voltage Stabilizers

          The NTC and the MOV will need to be checked from online datasheet.

          You can easily Google

          “4 amp NTC”, and “350 V MOV”, you will be able to find those from the existing online charts.

          Reply
  9. Shubham ingle says

    January 15, 2021 at 1:05 pm

    Hi Swagatam,

    how calculate the required resistor power rating for 1.2us X 50us pulse. with the resistance value of 200ohm and the mov clamping volatge is 1.5Kv.

    please let me know your feedback.

    Reply
    • Swagatam says

      January 15, 2021 at 7:04 pm

      Hi Shubham, sorry I do not have the formula for this calculations

      Reply
  10. Mark says

    January 11, 2021 at 12:10 am

    You suggest using an NTC resistor to protect against surges. However, since it is a negative temp coefficient device, its’ resistance will decrease when more current goes through it. Did you intend to suggest a PTC resistor?

    Reply
    • Swagatam says

      January 11, 2021 at 12:29 pm

      NTCs are intended for preventing the initial switch ON surge. Once the initial switch ON period is over the NTC is supposed to work with minimal interference and minimal resistance to current.

      Reply
  11. Seun says

    January 8, 2021 at 4:03 pm

    Please Sir, will the ntc and mov serve as current limiter for loads

    Reply
    • Swagatam says

      January 8, 2021 at 6:08 pm

      NTC will act as current limiter to an extent, but MOVs won’t.

      Reply
  12. S.Mani says

    December 2, 2020 at 5:12 pm

    The design of circuit using ntc,mov and line filter is good.
    I have seen many tv sets having ptc also.

    Reply
  13. Balcha says

    September 21, 2020 at 1:27 pm

    Swagatam Thank you i got answer for all of my questions.
    keep up the good work!.

    Reply
    • Swagatam says

      September 21, 2020 at 6:01 pm

      Thank you Balcha!

      Reply
  14. VL SOOD says

    September 3, 2020 at 12:15 pm

    I HAVE 3-PHASE 20 KW CONNECTION IN MY HOUSE. WHENEVER THERE IS SPARKING IN THE GOVT SUPPLY LINE SOME ELECTRONIC EQUIPMENT GETS DAMAGED. CAN I PUT THREE UNITS AS PEER YOUR CIRCUIT ON THE THREE PHASES AFTER MY MAIN 3-PHASE MCB FOR SURGE PROTECTION

    Reply
    • Swagatam says

      September 3, 2020 at 6:03 pm

      You can use the second design, and please do not write in capital letters.

      Reply
      • Swagatam says

        September 3, 2020 at 6:04 pm

        Use it in your specific equipment which get damaged, not in the 3 phase line.

        Reply
  15. VL SOOD says

    September 1, 2020 at 11:44 am

    I have a 3-Phase 20 KW connection in my house. The Electicity Board transformer is next to my house. Whenever there is a spark in in the transformer or supply line to my house, the home appliances get damaged. I understand this could be controlled with MOV. Could you please suggest a suitable circuit.

    Reply
    • Swagatam says

      September 1, 2020 at 4:41 pm

      Using high power MOV is the only remedy for such sudden voltage fluctuations, a permanent solution could be a triac based stabilizer circuit, which could be very large and complex to build.

      Reply
  16. chandan negi says

    August 21, 2020 at 6:08 pm

    Hi….Swagatam can you help me ac supply distortion .i have two switch one is 220 ac for my 12v pcb board.and other one for examination lamp also 220 ac.when i up down lamp 220 ac switch my 12v supply distortion and front display reset. i have used mov,pf,emi filter,

    Reply
    • Swagatam says

      August 22, 2020 at 10:57 am

      Hi Chandan, distortions can be corrected through inductors and capacitors or LC filters, as shown at the end of the above post. EMI filter should have worked…try increasing the inductor values.

      Reply
  17. Ankush says

    June 22, 2020 at 4:02 am

    Hi sir ,
    I am working on Street light timer
    But there is issue of voltage fluctuations
    I need surge suppressor what can u do ?

    Reply
    • Swagatam says

      June 22, 2020 at 11:55 am

      Hi Ankush, you can use an MOV or varistor for suppressing standard AC fluctuation surges.

      Reply
      • Ankush says

        June 22, 2020 at 5:38 pm

        Sir thanks for reply
        All ready I used mov but it burn and need to replace but I want circuit
        no need of replacemant of mov

        Reply
        • Swagatam says

          June 22, 2020 at 8:45 pm

          Ankush, in that case you will need a transformer based stabilizer, using triacs, or a PWM based stabilizer.

          Reply
          • Ankush says

            June 23, 2020 at 12:59 am

            Sir any refrance is available at your side?? Please give me

            Reply
            • Swagatam says

              June 23, 2020 at 9:42 am

              Ankush, what is the Voltage and current specification of the timer? I think you can use a capacitive power supply and have a constant voltage for the circuit.

              Reply
      • Dee says

        August 16, 2021 at 2:21 pm

        Hi, thanks for sharing your circuit diagram.

        Regarding circuit with two MOV & 10 Ohm R, i need to use it for my device, 230~235V input, protected from AC line at max 240V. It consume just 0.1 A (100mA~150mA) current.
        Based on the formula you gave, is it not too big for R?
        Supply- input V/I load = 240max – 230~235 / 100~150mA (0.1A) = ~2K R ?
        And is it go to high dissipations with that such value?

        Thanks.

        Reply
        • Swagatam says

          August 16, 2021 at 2:40 pm

          You are right, the formula doesn’t seem applicable for the MOVs, because then the MOVs won’t be required, and the resistors itself will effectively restrict the surge, and the dissipation will be extremely high.

          The formula should be simple R = V/I, where V can be the clamping voltage the MOV, and the current can be the maximum current the MOV can handle for a few microseconds.

          Let’s say the clamping voltage is 350V, and the max current limit is 50 amps, then the series resistor will be 350/50 = 7 ohms.

          Reply
  18. Robert Pointer says

    May 14, 2020 at 2:34 am

    Hello,
    I have a similar question:
    I have a ham radio amplifier wired for 240vac.
    It has an analog power supply. When first turned on the THUMP is very loud with inrush current. The filaments in the tubes do not like this very much and it shortens their life.
    I thought about using an NTC on each hot leads into the amp but I have no idea what value. The AC line is fused at 6 amp. Any suggestions?
    Thank you very much

    Reply
    • Swagatam says

      May 14, 2020 at 6:08 pm

      Hi, since the filament should be rated to consume low current, may be between 200 mA and 500 mA, a 5 ohm NTC should do the job nicely.

      Reply
  19. Fabio says

    March 15, 2020 at 4:32 am

    Hi Swagatom
    I am planning to install a main surge suppressor on my home.
    I did a schematic online, and I would like you to check it.
    The link is: https://ibb.co/Btddv8g
    I use MOV + TVS (The TVS diodes are b-directional)
    Do you thing will work?
    The board will be connect straight after the main circuit breaker in parallel not in series.

    Thanks

    Reply
    • Swagatam says

      March 16, 2020 at 1:03 pm

      Hi Fabio, it looks OK, but I don’t think the MOVs are required across earth and neutral! And even better to go for NTC instead of TVS…so NTC in series and MOV in parallel with the mains line would work better.

      Reply
      • Fabio says

        March 16, 2020 at 3:39 pm

        Hi Swagatam
        Thanks for your replay
        I live in Australia and on the main switchboard there is a link between Neutral and Earth.
        This because if Earth is not present in case of fault the Neutral became the Earth.
        Correct me if I am wrong but the NTC in series is just for inrush current.

        Thanks

        Reply
        • Swagatam says

          March 16, 2020 at 4:56 pm

          Hi Fabio,
          I was considering to streamline the design cost wise, but if you are OK with higher costs then you can go with the design that you have created, there’s no problem with it. Yes an NTC is for controlling in rush, which is also a major cause of equipment burning.

          Reply
    • Rosco says

      April 14, 2020 at 4:05 am

      Hi Fabio,

      The circuit might be fine (I’ve not analyzed it), however the layout is also crucial. You need to provide wide spacing between the tracks to prevent flashover if there is a high voltage incoming spike.

      Many compact devices providing this function ‘pot’ the circuit in epoxy to help prevent unwanted sparks across gaps between conductors and unwanted ‘creepage’ across the board substrate.

      I’d strongly suggest re-visiting the track spacing.

      Reply
      • Fabio says

        May 2, 2020 at 12:38 pm

        Thanks Rosco
        I have already printed all the PCB. I will follow your suggestion and maybe use epoxy!

        Thanks a lot!

        Reply
      • Rosco says

        May 3, 2020 at 4:06 am

        Cool cool…

        Want you to be safe so you can keep making stuff and publishing content… ☺️

        Reply
        • Swagatam says

          May 3, 2020 at 8:16 am

          Thank you!

          Reply
  20. Jainil Shah says

    January 28, 2020 at 12:00 pm

    Hi SWAGATAM, I want to have 10KV Surge protection in my 230V AC Mains circuit. Kindly assist me for that.

    Reply
    • Swagatam says

      January 28, 2020 at 4:40 pm

      Hi Jainil, what is the source of the 10kv, is it from lightening?

      Reply
      • Jainil Shah says

        January 29, 2020 at 9:39 am

        Yes, Source is Lightening.

        Reply
        • Swagatam says

          January 29, 2020 at 4:26 pm

          To protect against lightening you can apply the following circuit idea:

          lightening surge protector circuit

          This can be placed between the mains input and the load. When the input goes beyond 270V the triac will trip and blow the fuse. If required you can increase the 270V limit to 300V or higher.

          Reply
  21. Kennedy L Mtonga says

    January 22, 2020 at 5:55 pm

    Thanks a million. OK so lastly is is possible to shed more light on the components such as the diodes, the LED/LDR Assembly, and the Working voltage for the relay RL1 including component marked LD1. My real education is in computer networking and electronics was just a chapter so i am trying to beef up with the help of individuals lie yourself. Fortunately so. Hope its no bother. i intend to build it on a breadboard.
    Thanks once more.

    Reply
    • Swagatam says

      January 23, 2020 at 1:12 pm

      Thanks, I have updated the required details in the linked article.

      Reply
  22. Kennedy L Mtonga says

    January 22, 2020 at 3:08 pm

    Hi. I am stuck (not my name lol). I am a technician in the making. Just started learning. i am trying to design a circuit that only allows an adjustable current value (maximum 5 Amps on a supply voltage of 220 V). The operation is that drawing anything above the set current trips the load circuit but can be reset (reconnected by a reset button).
    The challenge is to limit the current draw under normal( no short circuit) conditions. Just to limit.
    Thanks in advance.

    Reply
    • Swagatam says

      January 22, 2020 at 4:39 pm

      No problem, I think you can try the following concept for the mentioned requirement

      https://www.homemade-circuits.com/mains-ac-overload-protection-circuit/

      Reply
      • Kennedy L Mtonga says

        January 23, 2020 at 1:18 pm

        Thanks a lot. will post and share on my research results once done.

        Reply
        • Swagatam says

          January 23, 2020 at 4:38 pm

          Ok great!

          Reply
  23. Shaun Halvorsen says

    December 17, 2019 at 12:58 pm

    Hello ,
    Could you advise me on the components need to monitor with a led on the third leg of a iTMOV on a 230v line please.

    Reply
    • Swagatam says

      December 17, 2019 at 5:33 pm

      Hi, you can try the following details:

      3 terminal MOV with LED indicator

      https://www.littelfuse.com/~/media/electronics/datasheets/varistors/littelfuse_varistor_tmov_itmov_datasheet.pdf.pdf

      Reply
    • Shaun Halvorsen says

      December 17, 2019 at 6:32 pm

      Hello ,
      Wow very fast answer ,really impressed ,just the answer i was looking for .
      I have some hifi equipment i want to connect a filter board to the mains and have some supresion before it .
      This will be good thank you so much ,very kind .
      Regards shaun Halvorsen.

      Reply
      • Swagatam says

        December 18, 2019 at 8:18 am

        Thank you, Glad I could help! Wish you all the best!!

        Reply
  24. Jan says

    August 20, 2019 at 11:56 pm

    Hi Swagatam,
    I will appreciate it if you can assist me with the following.
    I want to add surge protection to all of my 15A sockets in my house.
    Ref. to your circuit
    Home » Home Electrical Circuits » AC 220V/120V Mains Surge Protector Circuits
    The values of the components I intend to use is:
    Thermistor SCK201ROMSBY
    Size 20mm
    Termination Radial
    Tolerance ± 20%
    Tolerance Code M
    Max Steady State Current @ 25 deg C 13A
    Zero Power Resistance @ 25 deg C 1 Ω

    MOV 14D391K
    Size ` 14mm
    Max Allowable ACrms V 250V
    Max Allowble DC V 320V
    Varistor V @ 1ma 390V
    Max Peak I @8/20uS 4500A
    Max Energy 10/1000uS 100J
    Rated Power 0.6W
    Typical C @ 1kHz 510pf

    Do you think these will do the job?
    Your assistance will be much appreciated.
    Regards
    Jan

    Reply
    • Swagatam says

      August 21, 2019 at 8:58 am

      Hi Jan,

      It looks good, but if the RMS goes above 250V even for a second, your MOV will burn, better increase the RMS range to 300V.

      Reply
      • Jan says

        August 21, 2019 at 11:19 am

        Thank you Swagatam,
        I will certainly do that.
        Regards

        Reply
        • Swagatam says

          August 21, 2019 at 1:27 pm

          You are welcome Jan!

          Reply
  25. BIJU MICHAEL says

    August 5, 2019 at 9:07 pm

    What is the details of NTC resistor used with MOV. please give me details of NTC resistor…

    Reply
    • Swagatam says

      August 6, 2019 at 9:10 am

      It will depend on the load actually. For loads upto 1 amp, the value can be 5 ohms, a described in this article:

      https://www.homemade-circuits.com/using-ntc-resistor-as-surge-suppressor/

      Reply
  26. Nathan says

    June 24, 2019 at 8:25 pm

    Hello! I’ve got a somewhat complex question but not so difficult question that you can help me with. I’ll give you a little background as to WHY I am asking.

    I have just moved into a new house that only has a 15amp circuit in the office. My wife’s computer equipment alone places a heavy demand on this circuit and I know that by adding my computer I would very easily overload it. To solve this issue I ran a dedicated circuit just for my equipment. My PC can be very power hungry depending on load as I am into water cooling overclocking, etc. I also know that PC power supplies are typically a little more efficient when operating at 240v than 120 and I figured while I was running a new circuit I could just as easily run two. I used #12 wire and ran two circuits. One is set up for 120v and has a 5-20R receptacle. The second I configured for 240v and has a 6-20R receptacle. This portion of the project is done, everything is hot, I only need to move in and hook up my equipment, I have the appropriate power cord to hook up my PC. I have been looking though and have noticed that many of my other components, such as my monitors will also operate on 240v so I figure why not run as much on 240 as I can?

    Well as it turns out thus far the biggest reason why not is the ability to physically connect everything. My 240V circuit only has a single 6-20R receptacle and I have the need to plug in five or six devices. In the 120V world the simple solution is a power strip. I have had little success finding 240V power strips with 6-20R receptacles and those that I do find are $$$$. I figured I could build my own for a whole lot less money, or build a much superior product for the same money. A power strip is easy, but I figure if I’m going through the trouble I might as well build in surge protection and that’s where my lack of knowledge becomes a problem.

    As I understand it European “200” volt systems are configured as a Hot-Neutral-Ground configuration with 200V from hot to ground or hot to neutral. In contrast my US configuration will be Hot-Hot-Ground with 240V with hot to hot and 120V from either hot to ground if that makes any difference at all in system design. I was thinking of creating some kind of a box with a “bus” system, consisting of a bar or terminal strip for each leg and the ground. This would allow me to connect multiple receptacles to the bus in parallel and thus not have the possibility of drawing excess current through any one receptacle.

    Wish List:
    1. Fused (or circuit breaker) protection for both hot legs. I’m thinking some kind of circuit breaker would be good so it could kill both legs in the event that one side has a fault, like a double pole circuit breaker.
    2. High capacity surge suppression – Would it be more effective to have single surge protection point for the entire bus, or individual for each receptacle? My gut tells me that several smaller ones would be more effective than one large one but I could be dead wrong, I honestly do not know.
    3. Visual indicator of surge suppression function.

    Reply
    • Swagatam says

      June 25, 2019 at 8:48 am

      Hello Nathan,

      You can use calculated fuses on both the lines, because fuses are the cheapest way to handle a short circuit condition.

      It is better to have separate MOVs for each receptacle, than having a single large, as guessed rightly by you. Here’s a link that may help:

      https://www.homemade-circuits.com/how-to-select-mov/

      Visual indication for surge suppression can be impossible, because a surge may happen in milliseconds, and therefore impossible to track. However I have an idea which can be used for recording a surge occurrence, as explained in this article:

      https://www.homemade-circuits.com/surge-arrestor-circuit-with-surge/

      This can be modified as per user preference.

      Reply
      • Nathan says

        June 25, 2019 at 5:52 pm

        Thanks for the information! On the visual indication I wasn’t really looking so much for a way to see when a surge happened, but rather that the surge suppression was still working and wasn’t burned out. I’ve seen this on commercial power strips, kinda a built in self check if you will.

        Reply
        • Swagatam says

          June 25, 2019 at 8:17 pm

          You can add an LED across each fuse through a 56K 1 watt resistor. Meaning each LED must have a 56K 1 watt resistor in series. If the fuses blow the LED will switch ON, indicating the blown condition of the fuse. However this still won’t be able to show the condition of the MOVs whether they are actually working or not. Suppose if one of the MOVs become open internally, this cannot be identified by any means.

          Reply
          • Nathan says

            July 4, 2019 at 2:05 am

            Fair enough. Regarding the connections of the MOV’s. In a 240v HOT-HOT-GROUND scenario it seems you would have an MOV from each hot leg to ground. Assuming there was a surge on one hot leg which tripped the MOV and shunted it to ground, what would stop that same surge from tripping the other MOV and shorting leg to leg instead of to ground?

            Reply
            • Swagatam says

              July 4, 2019 at 10:11 am

              I don’t know much about HOT HOT GND connections and how these are configured? However a surge mostly won’t last more than a few microseconds, so if it’s grounded by the first MOV, it probably won’t reach the second MOV. If the surge lasts for more than microseconds could be enough to burn the MOVs or the MOV could catch fire.

              Reply
  27. Gajendra mishra says

    September 2, 2018 at 9:33 pm

    hi sir,
    first i try to explain you my system….which is regarding to operate 3 phase submersible pump from gsm based remote and data accusation also….
    in that metal sheet enclose contain electro-mechanical contactors, smps for gsm data logger for sms and gprs connectivity.
    problem is —
    1.some time when pump is off due to non power we found that when power comes suddenly electrical blast create in contactors at ac input terminals.
    2. some time when starter strat, gsm electronic immediate shutdown or restart, due to this pump cant start.
    3. in solar operated gsm logger , found that in rainy season modem became hang.
    i think all above are due to electrical surge..
    sir please guide me how to solve it, i want to make a spd solution for above …..

    Reply
    • Swag says

      September 3, 2018 at 8:26 am

      Hi Gajendra, for controlling surge you can try a delay ON timer circuit, as explained at the bottom section of this article:

      https://www.homemade-circuits.com/simple-delay-timer-circuits-explained/

      You can replace the relay with a 3 contact relay for connecting the 3 phase through the relay.

      the delay ON could be set by adjusting the values of C2/R2. The emitter zener diode is not required and could be replaced with a wire link

      Reply
  28. Voon Yongjian says

    April 13, 2017 at 1:38 pm

    Hi sir,
    I am designing a surge protection device for lightning. Is the design above is suitable for it? Can I replace the resistor with an inductor because i saw it somewhere in other website?

    Basically my input supply will be 240 Vac, what is the value of clamping voltage of MOV is suitable? Can I use MOV with 240V clamping voltage?

    Thanks!

    Reply
    • Swagatam says

      April 14, 2017 at 2:59 am

      Hi Voon, if the lightning strikes directly into the house wiring then no surge suppressor would be capable of stopping it.

      MOV can suppress only minor electrical surges, not lightening related surges….to suppress lightning related surges the best idea would be to employ a triac based crowbar circuit as described here

      https://www.homemade-circuits.com/2017/03/surge-arrestor-circuit-with-surge.html

      the high voltage capacitor and diode can be ignored and removed.

      you can also include an MOV/inductor suppresor as per your initial requirement in conjunction with the above design.

      Reply
  29. RAO says

    March 21, 2017 at 1:58 pm

    Namasthe,
    I am talking about the " Ajantha make wall clock : OLC Quartz 104, Model. computer century Calendar", which I am using. There is a supply module inside the clock. Every time there is a power shout down in our area and the power comes up, the clock fails. The watch repairer says supply unit is burnt. So I just wanted to incorporate a surge suppresser to this clock externally.

    Reply
    • Swagatam says

      March 22, 2017 at 2:55 am

      OK I understood, the in-built power supply could be an SMPS based…..as expressed in above comment you can try connecting an NTC in series with any of the supply lines, and also connect an MOV across the two supply lines after the NTC.
      I'll try to update the diagram soon for your reference

      Reply
  30. RAO says

    March 20, 2017 at 9:12 am

    I have an electronic digital calendar clock, its supply unit has bagged off three times due to surge voltage in the mains. I want to incorporate a simple sure suppressor for it. it may be drawing less than on ampere current. what value components are recommended. please advise me if any simplest circuit which I can assemble myself.

    Reply
    • Swagatam says

      March 21, 2017 at 4:02 am

      Normally any god power supply will never burn with minor supply fluctuations….what kind of supply unit have you been using? Is it SMPS based or transformer based?

      I would suggest you to use your cellphone charger for the purpose which has all the protections in-built

      still if you are interested to build your customized surge suppressor, you can try an NTC in series with any of the input mains supply lines, and additionally connect an MOV across the two supply lines after the NTC.

      Reply
  31. Ravi kumar says

    September 16, 2016 at 4:00 am

    Hi Swagatam,

    I'm planning to install a surge suppressor for the whole house at the mains AC panel (next to the meter board) is there a standard part available available off the shelf or do we need to design one and install. i was able to find CHSPT2MAX from Eaton, but its too expensive, any suggestions…

    Reply
    • Swagatam says

      September 16, 2016 at 5:04 am

      Hi Ravi, you an industrial MOV, in conjunction with the following delay ON relay crcuit, adjust the delay time to may be a second or so, and connect the relay contacts with the house wiring.

      https://www.homemade-circuits.com/2013/02/make-this-simple-delay-on-circuit.html

      Industrial MOV sample is discussed below

      https://www.homemade-circuits.com/2015/01/high-power-industrial-surge-suppressor.html

      Reply
  32. patrick vaz says

    September 11, 2016 at 3:11 pm

    Hi Swagatam,

    How are you,
    A friend of mine had his TV friend due to a voltage surge,
    Voltage Input from the mains line is 230V, sanctioned current is 6amps. want to help him out.
    Can I use the circuit mentioned above 2 MOV with 10ohms 2 watt resistor,
    -what should the value of the MOV be.
    – what should the value of the fuse be in terms of AMPs.
    – should a Indicator lamp be added in the circuit after the fuse,
    Kindly advise.
    warm regards

    Reply
    • Swagatam says

      September 12, 2016 at 3:34 am

      Thanks Patrick, I am good!

      yes you can try it, just replace the resistors with 1 ohm 2 watt, because 10 could be a bit too high.

      MOV could be rated at 350V (clamping voltage)

      fuse could be an 8 amp rated….

      indicator lamp is optional, it can be added for indicating a blown fuse

      Reply
    • patrick vaz says

      September 12, 2016 at 1:18 pm

      Hello Swagatam,

      Thank you so much,

      Apart from the Mains, it could be added in different sections of the house, where sensitive equipments are such as TV/ Music systems etc., just to be safe.

      Is this okay ?

      warm regards

      Reply
    • Swagatam says

      September 13, 2016 at 2:30 am

      Thanks Patrick, yes you can use an MOV with every appliance but MOV has its own restrictions too, for example it might not withstand the surge if it lasts for more than a millisecond, and could cause a short circuit and fire, therefore a series fuse also becomes mandatory.

      Alternatively you can use a single powerful MOV near the main DP of the house, the MOV specs are explained below

      https://www.homemade-circuits.com/2015/01/high-power-industrial-surge-suppressor.html

      By the way all modern equipment already include a built-in MOV in their system

      Reply
  33. shivtej nirmal says

    August 31, 2016 at 6:45 pm

    What MOV VALUE and part no

    Reply
    • Swagatam says

      September 1, 2016 at 4:58 am

      can be a 350V MOV

      Reply
  34. Narciso Calzo says

    July 10, 2016 at 10:23 am

    Hi Swagatam,

    I was looking for a surge suppressor device circuit diagram and was directed to your site. Upon reading about you and going through the comment and replies between you and your readers, your patience in answering all the queries really put me in great admiration to you. I came across so many people like you in the web but you are different from them, they can't respond.

    Recently I just decided to become a hobbyist in electronics although I don't have a formal education or training about it but a steward/stewardess can land a commercial plane with the guidance of the ground controllers( this is from a movie).

    I was inspired by a friend that showed me his DIY audio amplifier and it works well. I asked him for the details and he gave me copies of schematics, pcb layout, parts list as well as procedures of adjustments but it is limited to a 100W into 8ohm power. I want to evolve this to a 350W,8ohm design. The design uses 2SC5200 output devices and TIP41C drivers.

    Can you give me suggestions, advices or even a new design from you, or, is it okey to publish the circuitry since it was designed by an EE in order for you to go through it and come up with solutions and recommendations to meet the desired power for my first project.

    Actually I have already etched the pcb the very conventional way. By the way I am from the Philippines, work as a material eng'r in a construction company.

    Nice knowing you Swagatam.

    Your new reader/jollower,

    Osic

    Reply
    • Swagatam says

      July 10, 2016 at 3:08 pm

      Hi Osic, thanks so much! I appreciate your enthusiasm and wish you the very best!

      Amplifiers can be quite difficult circuits as they require precision and balance at every node and stages of the circuit and so far I have not been able to master these gadgets due to their complex concepts and configurations.

      So I am really sorry I won't eb able to assist you with amp designs, therefore I would recommend you to select a schematic which is originally designed to suit your specifications instead of modifying a design having a different specifications.

      I have a 100 watt simple mosfet amplifier circuit in this site designed to work with around 35V normally which is capable of generating upto 300 watts power simply by using a higher voltage input of around 100V…however it requires a 4 ohm speaker, If you wish you could try that design also!!

      Reply
    • Narciso Calzo says

      July 11, 2016 at 10:38 am

      Okay Swagatam I will take a look at your design. Thanks Swagatam, more power.

      Reply
  35. Lim says

    January 15, 2016 at 9:48 pm

    Hello!
    A friend of mine was thinking of building a surge suppressor and voltage regulator by using ARM microprocessor. He was thinking of using inductor plus MOVs together. Do you think it is feasible?
    Thank you.
    Lim.

    Reply
    • Swagatam says

      January 17, 2016 at 5:17 am

      Hello,

      MOVs don't require any external triggering circuit for activating, it's a self-actuated device so I don't think an MCU could be used for operating an MOV

      Reply
  36. Makhon Barooah says

    November 28, 2015 at 1:19 pm

    ko good, but we want buy pcg/ components/ etc in india. is it possible in india?

    Reply
    • Swagatam says

      November 30, 2015 at 11:37 am

      yes, it' possible.

      Reply
  37. Mark Mare says

    November 27, 2015 at 3:51 am

    Dear Mr Swagatam

    Firstly thank you for this great website, i have built a few small projects of your design, i have become extremly interested in transient voltage and the long term damage it does. I will test the above circuit and give some feed back.

    What i would like to ask is (if you perhaps have an existing) a design where one can "monitor" the transient voltage on a incoming line (the main grid). I understand that there are "in line counters". This can be a great tool to take the readings before and after the unit install.

    Will this be possible?

    Again thank you for the great site and info.

    Best Regards
    Mark
    South Africa
    mrmcon@gmail.com

    Reply
    • Swagatam says

      November 28, 2015 at 3:38 am

      Thank you dear Mark,

      The simplest way could be to connect a digital ammeter in series with the MOV that may have a feature to latch up to the reading corresponding to the transient value each time power is switched ON.

      If it's possible I'll try to design and post it for you.

      Reply
    • Mark Mare says

      November 28, 2015 at 4:05 am

      Thank you very much Sir.

      Reply
  38. cloyd mamontayao says

    August 22, 2015 at 4:26 pm

    The upper diagram sir is what we wanted to do (parallel to the source) but we are not sure if it can supress the voltage surge thats why we decide to design another (lower diagram) which is connected in series from the source. i'm begging for your expert suggestion and advice sir that can help a lot to our device to function and for us to pass the subject. thank you sir SWAGATAM.

    Reply
    • Swagatam says

      August 23, 2015 at 2:11 pm

      normally all TVSS devices are extremely reliable and can be trusted for the necessary actions.

      you can refer to the following article for more info:

      https://www.homemade-circuits.com/2014/09/testing-mov-metal-oxide-varistor-surge.html

      Reply
  39. cloyd mamontayao says

    August 22, 2015 at 4:14 pm

    this is the diagram of our device sir.. the source is Line to Line. we just put the ground into the device for the MOV's.

    https://drive.google.com/open?id=0B786VWhN4zxiTzlmeUhQRml4R2M

    Reply
    • Swagatam says

      August 23, 2015 at 2:07 pm

      …please toggle the share option…

      Reply
  40. cloyd mamontayao says

    August 14, 2015 at 1:44 am

    Hi Mr. Swatam, do you have a schematic diagram for TVSS or SPD for resedential use only. pls include the value of materials.

    thank you so much.

    Reply
    • Swagatam says

      August 14, 2015 at 11:53 am

      Hi Cloyd,

      you can probably try using the devices explained in the following article:

      https://www.homemade-circuits.com/2015/01/high-power-industrial-surge-suppressor.html

      put these directly across the wires that enter the house wiring.

      the value can be of 350V/50amp

      Reply
    • cloyd mamontayao says

      August 22, 2015 at 4:00 pm

      Hi Sir Swagatam, thank you for your response. i want to ask you more question sir about TVSS/SPD , This is for our thesis sir and i'm hoping that you can give us more details about the connection. we are troubling of our design sir because we would like to make a TVSS device that will connected parallel to the source (40A Breaker), thus we doubted our design due to its connection if it can really suppress the voltage surge. i will show you our design sir and were hoping that you can give us some advice on how to fully get the right design.
      thank you for your time sir Swagatam, best regards.

      Reply
    • Swagatam says

      August 23, 2015 at 2:06 pm

      Hi Cloyd,

      The link which I suggested you in the earlier comment can be effectively used as a transient voltage surge suppressor.

      Other option is in the form of diodes which is explained here, these also need to be connected parallel to the input mains supply:

      https://en.wikipedia.org/wiki/Transient-voltage-suppression_diode

      The image provided by you is not opening, please make it "public" by selecting the share option.

      Reply
  41. Roberto Carmona says

    October 22, 2014 at 9:18 pm

    Hi Mr Swatam. Cogratulation for your extraordinary electronic web page…….

    I write from México. My question is: For a 120v nominal voltage, what should be the value of the resistors, and the maximun peak voltage and Joules for the MOV's ?

    Thanks in advance for your help…….

    Reply
    • Swagatam says

      October 23, 2014 at 4:18 am

      Thanks Roberto,

      for 120V you can select 200V as the clamping voltage for the MOV, the resistors are not critical they are just for complementing the MOVs, any value between 0.5 ohms to 1 ohms will do the job.

      10 ohm is far too big and must not be used, it's incorrectly shown in the diagram.

      Reply
  42. Makhon Barooah says

    October 6, 2014 at 2:11 am

    Value of MOV and best company product….thnx.

    Reply
  43. Makhon Barooah says

    October 6, 2014 at 2:09 am

    Plz. value of MOV and best one company product……thnx.

    Reply
    • Swagatam says

      October 6, 2014 at 12:13 pm

      company is not important as all are good, the clamping voltage rating should be 50 V more than the input mains supply voltage.

      Reply
  44. Nilesh says

    May 28, 2014 at 6:22 am

    Hi Swagatam ,

    How are you ? hope doing well.

    If want to draw constant 220 v AC at any point

    Generally input is
    Low – 110v / 130v AC
    High – 230/260 v AC

    Required Output
    220 V AC (Stabilized)

    Can you please suggest best circuit . if Tranformerless will preferable.

    Thanks
    Nilesh Patil

    Reply
    • Swagatam says

      May 29, 2014 at 4:05 am

      Hi Nilesh,

      I am fine, thanks!

      You can try the design that's shown in the following article:

      https://www.homemade-circuits.com/2011/12/how-to-make-accurate-7-stage-op-amp.html#uds-search-results

      a transformerless design could be very difficult since it would involve complex mosfet drivers, ferrite inductors etc, so I think using the traditional iron core transformer would be much easier, although a little bulky.

      Reply
  45. chris.sorbi says

    April 19, 2014 at 12:36 am

    Hi,

    Is it possible to use this diagram for a single wire ground return system? My power line is a single phase 240V and the neutral is coming from a copper rod in the ground. The voltage fluctuates a lot and i would really like to protect my devices (Mainly motors and VFD's) and some computers. Do you recommend any other systems like high and low surge protection? Also, what protection rating should i expect (high voltage vise)

    I appreciate your response in advanced.

    Chris

    Reply
    • Swagatam says

      April 19, 2014 at 4:25 am

      Hi,
      the above circuit will only help to control surge in-rush to some extent but won't control the voltage fluctuations.

      you would need a voltage stabilizer circuit for tackling the issue effectively, one design has been discussed below which may be tried or procured readymade:

      https://www.homemade-circuits.com/2011/12/how-to-make-accurate-7-stage-op-amp.html#uds-search-results

      Reply
      • CT Simms says

        January 4, 2022 at 6:49 pm

        Hello Swagatam,
        I would like to install a whole house surge/spike protector.I have a 120/240 VAC 200 amp single phase supply,with the neutral carrying the unbalanced load.I want to install 4 mode protection below the main breaker.L1/L2,– L1/N,—L2/N,—N/Gnd.The Neutral/ground may be redundant,but I am a belt-and-suspenders kind of guy.This is a sub-fed panel so the Equipment ground and Neutral are not bonded at the panel.
        I would also like to install an indicator light to indicate normal/fail status of the MOV’S.
        Thanks in advance for your help on this matter.

        Reply
        • Swagatam says

          January 5, 2022 at 11:55 am

          Hello CT, yes you can definitely try the concept for your application. Connecting MOVs across the mentioned areas might help you control the intermitent vltage spikes.

          Having an LED indication for the MOVs might be difficult unless you also employ a fuse with each of those MOVs.

          Reply
    • Moses says

      January 10, 2022 at 4:26 pm

      Can I use 101k inductor with the specs listed below in series with NTC and 2500 capacitor to create a similar effect because that is what is available in my area and I do not know where to get a ferrite core that I will use to make the 3.1uH that you have specified above. If not what can be a replacement for that because I want make a surge protector for my tv. Technical Specifications
      Abracon AIUR-03-101K technical specifications, attributes, and parameters.

      Reply
      • Swagatam says

        January 10, 2022 at 6:11 pm

        The coil inductance needs to negligibly low, so the mentioned inductor cannot be used. The inductor could be built by winding around 40 to 50 turns of copper wire over an iron core

        Reply
  46. Shersingh Badhoriya says

    December 28, 2013 at 6:51 am

    Hi….Swagatam can u give the VA rating of mov & fuse of above ckt u used above….when my ckt I/p current is 130mA and o/p current is 170mA & o/p voltage is 167 when I/p voltage is 230V for electronic ballast. ….so please share it with me asap….

    Reply
    • Swagatam says

      December 28, 2013 at 2:39 pm

      Hi Shersingh,

      you can use a 350V RMS, @5amp rated MOV.

      Reply
  47. Swagatam says

    December 12, 2013 at 2:20 pm

    telephone surge protector?? i didn't get the application, can you pls explain it?

    Reply
  48. Swagatam says

    August 12, 2013 at 6:17 am

    No it's not due to spike, it's due to a split second late response from the UPS, try with a new good quality UPS and you won't find this issue happening.

    Reply
  49. Swagatam says

    August 11, 2013 at 7:42 am

    For what application do you want to use it?

    Reply
    • Moses says

      January 10, 2022 at 6:48 pm

      Can I use a piece of nail as the iron core
      if better ones are unavailable or maybe use a few turns of iron wire or copper wire

      Reply
      • Swagatam says

        January 10, 2022 at 7:27 pm

        You can use a small iron bolt. A nail may be too thin to be effective. Iron wire will be much better since it will offer the required resistance to the surge.

        Reply
  50. Swagatam says

    July 15, 2013 at 3:31 pm

    You can incorporate thermistors and MOVs together, resistors can be avoided then.

    for knowing more about thermistors, you may refer to this article:

    https://www.homemade-circuits.com/2013/02/using-ntc-resistor-as-surge-suppressor.html

    Reply
    • Moses says

      January 10, 2022 at 7:34 pm

      Is there any need for slightly insulating the iron bolt before the first winding since the bolt has toothed edges to avoid scratching the wire.

      Reply
      • Swagatam says

        January 10, 2022 at 8:19 pm

        yes, you can apply a layer of insulation tape over the bolt…

        Reply

Primary Sidebar



Categories

  • 3-Phase Power (15)
  • 324 IC Circuits (19)
  • 4017 IC Circuits (52)
  • 4060 IC Circuits (25)
  • 555 IC Circuits (98)
  • 741 IC Circuits (19)
  • Amplifiers (59)
  • Arduino Engineering Projects (83)
  • Audio Projects (94)
  • Battery Chargers (83)
  • Car and Motorcycle (94)
  • Datasheets (46)
  • Decorative Lighting (Diwali, Christmas) (32)
  • DIY LED Projects (89)
  • Electronic Components (97)
  • Electronic Devices and Circuit Theory (35)
  • Electronics Tutorial (109)
  • Fish Aquarium (5)
  • Free Energy (34)
  • Fun Projects (12)
  • GSM Projects (9)
  • Health Related (19)
  • Heater Controllers (28)
  • Home Electrical Circuits (100)
  • How to Articles (20)
  • Incubator Related (6)
  • Industrial Electronics (28)
  • Infrared (IR) (40)
  • Inverter Circuits (98)
  • Laser Projects (12)
  • LM317/LM338 (21)
  • LM3915 IC (25)
  • Meters and Testers (64)
  • Mini Projects (156)
  • Motor Controller (66)
  • MPPT (7)
  • Oscillator Circuits (24)
  • PIR (Passive Infrared) (8)
  • Power Electronics (33)
  • Power Supply Circuits (74)
  • Radio Circuits (9)
  • Remote Control (47)
  • Security and Alarm (61)
  • Sensors and Detectors (118)
  • SG3525 IC (5)
  • Simple Circuits (74)
  • SMPS (29)
  • Solar Controllers (60)
  • Timer and Delay Relay (53)
  • TL494 IC (5)
  • Transformerless Power Supply (8)
  • Transmitter Circuits (40)
  • Ultrasonic Projects (14)
  • Water Level Controller (45)


Circuit Calculators

  • AWG to Millimeter Converter
  • Battery Back up Time Calculator
  • Capacitance Reactance Calculator
  • IC 555 Astable Calculator
  • IC 555 Monostable Calculator
  • Inductance Calculator
  • LC Resonance Calculator
  • LM317, LM338, LM396 Calculator
  • Ohm’s Law Calculator
  • Phase Angle Phase Shift Calculator
  • Power Factor (PF) Calculator
  • Reactance Calculator
  • Small Signal Transistor(BJT) and Diode Quick Datasheet
  • Transistor Astable Calculator
  • Transistor base Resistor Calculator
  • Voltage Divider Calculator
  • Wire Current Calculator
  • Zener Diode Calculator


You can also Chat with me here:

Facebook
Twitter
YouTube
Instagram
My Facebook-Page
Quora



© 2022 · Swagatam Innovations

We use cookies on our website to give you the best experience.
Cookie settingsAccept All
Privacy & Cookies Policy

Privacy Overview

This website uses cookies to improve your experience while you navigate through the website. Please visit the Privacy Policy Page for more info.
Necessary
Always Enabled
Necessary cookies are absolutely essential for the website to function properly. This category only includes cookies that ensures basic functionalities and security features of the website. These cookies do not store any personal information.
Non-necessary
Any cookies that may not be particularly necessary for the website to function and is used specifically to collect user personal data via analytics, ads, other embedded contents are termed as non-necessary cookies. It is mandatory to procure user consent prior to running these cookies on your website.
SAVE & ACCEPT