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Home » Power Supply Circuits » Add this Short Circuit Protection to Your Power Supply

Add this Short Circuit Protection to Your Power Supply

Last Updated on March 24, 2022 by Swagatam 87 Comments

A rather cheap yet reasonably effective short circuit protection circuit is explained below which can be used for safeguarding power supply circuit

Introduction

A power supply unit is an indispensable unit for every electronic enthusiast and engineers working in the relevant field. Though today all of us use hi-tech power supply units having built-in protection, there are folks who still rely on ordinary types of power supply units with no protection facility.

The biggest enemy of all power supply units is a possible short circuit that might occur at its output terminals due to an accidental connection or due to the fault with the connected load.

There are various electronic circuits that might be employed with a power supply unit for checking this problem, however these circuits sometimes themselves are at risk of getting damaged due to the limitations with many electrical parameters.

A very innovative way of rectifying this problem has been shown in this article. A single relay is used for sensing as well as tripping the output from the involved malfunction.

Circuit Operation

Referring the circuit diagram, we see that a relay is connected directly to the output of the power supply DC output, however the connection is made through the N/O contacts of the relay. These contacts are also terminated as the output of the unit.

N/O means normally open, that means the contacts are open initially, which in turn keeps the output disconnected from the positive of the power supply.

Now when the shown push button is momentarily pushed, the N/O contacts are bypassed allowing the current to flow across the relay coil.

The relay coil energizes, closing the N/O contacts, which in turn latches and sticks to the position even after the push button is released.

The relay latch maintains this latched position as long as the output is used under normal conditions, but in an event of a short circuit across the output terminals, there may be a sharp drop in voltage, the instant this voltage drops below the coil voltage of the relay, it loses its holding strength and immediately releases the contacts, and trips, cutting OFF the supply to the output and in the course switches OFF the latch preventing the short hazard conditions.

This brings the relay to its initial condition and needs resetting in order to restore power at the output.

The circuit diagram for the power supply short circuit protection is shown below:

Short Circuit Protection for Variable Power Supply Circuit

If you are having a variable power supply and want the short circuit operation to work even at voltages below 3 V or 1.5 V, then you can try adding the following short circuit protection circuit to your power supply circuit.

The idea was designed and submitted by one of the avid readers of this blog.

The above was tested and found to be working satisfactorily. The images show how the circuit was practically implemented into a variable power supply unit.

You'll also like:

  • 1.  100 amp Variable Voltage Power Supply Circuit
  • 2.  Soft-Start Power Supply for Amplifier Loudspeakers
  • 3.  IC 723 Voltage Regulator – Working, Application Circuit
  • 4.  How IC LM337 Works: Datasheet, Application Circuits
  • 5.  1.5V to 12V DC Converter Circuit for LEDs
  • 6.  Operating Single Rice Bulb Lamp with 220V AC

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!

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Reader Interactions

Comments

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  1. Swagatam says

    Thanks! Relay voltage should always match the supply voltage, therefore for 27V the relay should be rated at 24V.

    Reply
  2. Swagatam says

    you can try this circuit, it will provide both over current and short circuit protections for the transformer.

    https://www.homemade-circuits.com/2013/07/simple-ac-mains-short-circuit-protector.html

    Reply
  3. Swagatam says

    you can put it anywhere you like, before or after the regulator….it will do its job as specified.

    by the way if you are using a 78XX regulator then you probably wouldn't need the above arrangement because all modern regulator have built-in short circuit protection and are litrally blow-out proof

    Reply
  4. Swagatam says

    The DC comes from the AC after all. So the AC control will be directly proportional to the DC.

    Anyway with a 337 IC you can do the following:

    use a BC557 transistor.
    connect collector to ADJ, emitter to ground-relative to (-).

    connect base to ground via a 100 ohms and put another resistor between the emitter ground connection and base ground connection…meaning the emitter/ground joint and base/ground joint must be bridged with a resistor.

    This resistor decides the current limit.

    find it by using R = 0.6/limit current = Ohms.

    Reply
  5. Swagatam says

    connect another LED across relay N/C and ground via 1K resistor.

    Reply
  6. jerald dacaymat says

    sir, does it resets automatically or we should do something for it to have a reset function?

    Reply
    • Swagatam says

      No it won't, you will have to press the push button to reset it back into action. There's no automatic option for this simple design.

      Reply
  7. Janesh Joshi says

    Hi Swagatam, Is there a way to use this circuit for a variable power supply ? What modifications will be needed ?

    Reply
    • Swagatam says

      Hi Janesh, No modifications would be required, just connect the variable power supply circuit with the output of the above shown design

      Reply
  8. Daniel says

    Hi Swagatam! I've built the circuit and it works great! thanks!
    I just have two questions:
    1 ) is the diode really needed? what is it for? having it means that I will always have a 0.7 voltage drop and I would like to avoid it because i'm puting the circuit after a previously regulated power supply.
    2 ) Is it safe to use this circuit as a short circuit "detector" to repeatedly check solderings, etc. (as I usually do with the buzzer in my multimeter)

    Reply
    • Swagatam says

      Thanks Daniel,

      The diode can be removed.

      this circuit is a crude design and will work only for high current short circuit scenarios….it's not suitable for detecting low current soldering faults.

      Reply
  9. Daniel says

    hi again,
    Thanks for your responses 🙂
    As I said before, I'm placing this circuit after a voltage regulator. The problem now is that when I regulate the voltage to lower than 3.5 volts, the relay opens, so I cant use lower voltages than that. The reason why this appens is quite obvious, I just wanted to ask if you have any suggestion on how to solve it.

    By the way.. have you thought of this circuit as being one bit of digital memory?

    Reply
    • Swagatam says

      Hi Daniel, it's a crude circuit for achieving a short circuit control, it can be easily modified for a better response by just adding a BJT with it, i'll try to update it soon…this modification will allow volatge inputs below 1 V.

      yes most latch circuits could be considered as a 1 bit memory circuit…

      Reply
    • Daniel says

      Following your advice and the instructions given on http://www.ikalogic.com/bjt-switches/ , I've built the following circuit:

      https://www.dropbox.com/s/7pw61zck3wj1ppj/short%20circuit%20protection%20V2.png?dl=0

      It works! Although I had to eliminate the capacitor because it wasn't allowing the relay to switch off… I didnt understand why…
      Please give-me your feedback, i'm not sure if I'm doing what you had in mind.
      Thanks for your help!
      Regards, Daniel

      Reply
    • Swagatam says

      In my prototype the relay was making a lot of noise while switching off while I was testing it with an output short, ……….adding the capacitor instantly solved the chattering issue therefore I had to include the capacitor in parallel with the relay coil.

      Reply
  10. joshuat says

    hi swaggatam, how do you make a circuit like above to short circuit protect a lithium bank of 200v?
    Im working on a project and i noted that an accidental increase in current draw would lead to fires,

    Reply
    • Swagatam says

      Hi Joshua, you could try the following concept:

      https://www.homemade-circuits.com/2011/12/how-to-make-mains-av-short-circuit.html

      remove the triac/R4, and replace R3 with a relay coil, the relay contacts can be then wired with the load in series with the 200V battery supply.

      The indicated mains input gets replaced with the 200V input

      Reply
    • Swagatam says

      …C1 must also be removed, and R6 replaced with a 10K 5 watt resistor

      Reply
  11. Gary John Yu says

    hi swagatam
    can you please guide me i would like to make a variable resistor, which component should i replace and value? i already have transformer which is 24v 6amp. thanks advance

    Reply
    • Swagatam says

      Ho Gary, did you mean a variable voltage power supply? please clarify.

      Reply
  12. Gary John Yu says

    edde

    Reply
  13. Gary John Yu says

    hi swagatam, can you please guide me what component and value should replace in diagram i want to make an variable resistor which is 30v is the max output by using an 24v 6amp transformer

    Reply
  14. Anil Kumar. K says

    Hi Swagatham
    Can you publish an LM317 based 1.25V to 24V, 5A variable powersupply circuit. I know 317 can only handle 1.5A, so a power transistor(s) can be used to handle current more than 1.5A.
    But I don't want that bulky power transistor. I prefer an N-Channel power mosfet for enhansing LM317's current capacity. Is it possible….?
    I searched google for such a circuit, not yet found. If you can add output SHORT CIRCUIT PROTECTION, with latching/auto reset after removing short circuit. That will be an added advantage.

    Reply
    • Swagatam says

      Hi, Anil,

      although a BJT looks more appropriate as the outboard current booster device since it requires just 0.7V to trigger, let's try this with a mosfet and see how it responds…I'll design and post it soon.

      Reply
    • lokesh lokesh says

      hi Anil Kumar. K
      if possible check this by copy pasting below

      "LM2577S + LM2596S dual chip modules, DC-DC step up step down module "

      in ebay.in hope ur requirement gona match

      Reply
  15. lokesh lokesh says

    hello sir as u said above "could be used in variable power supply unite. ." how does relay going to react in case of low voltage is being set eg: 12max out put relay set to 12vminmum if turn down voltage to 2v then I hope relay going to be Delatch .? right sir ?
    Thank you in advance

    Reply
    • Swagatam says

      Hello Lokesh, the variable supply stage will need to be after the relay, meaning the relay contacts will be supplying the variable circuit stage, and the output from the variable circuit supply will finally reach the load.

      The relay stage will be associated with the bridge rectifier, and the relay coil will need to be rated as per the bridge output voltage

      Reply
    • lokesh lokesh says

      Thank you for replying sir..
      actually I am planning to put buck boost converter
      (LM2577S + LM2596S dual chip modules, DC-DC step up step down module )

      … Instead of 78xx since its too hot to handle. .

      ok as u said if I connect this system before
      buck boost module. .. does it functions same.?

      and more querie does the buck boost module support short circuit cut off.?

      Reply
    • Swagatam says

      Lokesh, if you have planned to use a LM2596S circuit then a better and more logical idea would be to use its pin5 for the overload shut down…the above relay method would be too crude for this.

      If possible I'll try to post the whole idea soon in my blog.

      Reply
    • lokesh lokesh says

      ho nice.. but I am using ready kit bought from ebay if u type

      "(LM2577S + LM2596S dual chip modules, DC-DC step up step down module )"

      u may get it.. sir in ebay website hope u get an idea about it.. since I am not confirm that's y worried. . hope I can get solution as soon as possible. . 🙂

      Reply
    • Swagatam says

      would you take the risk of accessing the shut down pin of any of those ICs and link it with an external circuit? if not then it's better to go for a linear current limiter circuit at the input, as shown below:

      https://www.homemade-circuits.com/2013/06/universal-high-watt-led-current-limiter.html

      Reply
    • lokesh lokesh says

      ok I will try sir..Thank you for ur efforts to support me..
      also let me how can I prepare an
      "Add on circuit " for converting
      square wave out put of 230v to sine wave ?

      Reply
    • Swagatam says

      you can refer to the following post for learning more regarding how to modify square to PWM sine waveform:

      https://www.homemade-circuits.com/2013/04/how-to-modify-square-wave-inverter-into.html

      Reply
    • lokesh lokesh says

      Thank you for replying sir.. I have checked the link. .. and I feel that circuit is made for building newly. .but I am looking for circuit which can be added at the end of square wave 230v 45w inverter. . which is presently not supporting any Transformer and capacitive step down type load.. due to square wave out put.. hence I was looking for minimal change in inverter so that I can run above mentioned load too..
      hope my msg is convinced. ..

      Thank you

      Reply
    • Swagatam says

      you can try the C1/C2/L1 configuration as shown in the following diagram, and see if that helps:

      4.bp.blogspot.com/-khKat0UA8Jw/UITpCnNd7yI/AAAAAAAAA_A/8x-KAD2aHLE/s1600/simplest60+Hz+Inverter+circuit+diagram.jpg

      Reply
    • lokesh lokesh says

      Yes something like this I was looking for thank you sir.. just need to find what the value for 230v 45 w that's ok I will tryout..

      and also let me know. ..

      So eagerly waiting for circuit which will be having following (few or all) features -Low Battery Cut-off
      – Overloading protection
      – Short Circuit protection
      – Reverse current protection
      – Reverse polarity protection
      – Thunder protection
      – Over discharge protection
      – Auto battery shut-off at Low voltage detection
      – Overcharge protection
      – Auto charge stop/ High Volt Detection
      – Battery capacity level display(SOC)

      Making this circuit for underprivileged location as donation for poor via charity So hope I can have one ckt diagram with some or all features mentioned above or lts link.. Looking for ur reply ..
      With full excitement

      Thank you
      Regards
      Lokesh

      If successful I am in plan to put ur & website name on my device As part of tribute to you sir

      Reply
    • Swagatam says

      I have already posted this circuit, here's the link:

      https://www.homemade-circuits.com/2015/10/smart-emergency-lamp-circuit-with.html

      Reply
    • lokesh lokesh says

      Thank you for replying. ..
      plz also let me know the simple circuit which can be used to charge 24/12/9/3vDC battery ..
      (based one preset settings .. )

      with minimum below options or better then this.:

      1)Disconnect input after (set) full charge.

      2)Disconnect output after (set) minimum level. to avoid Deep discharge

      Reply
    • Swagatam says

      you can try the second circuit from the following link:

      https://www.homemade-circuits.com/2011/12/how-to-make-simple-low-battery-voltage.html

      for 3V battery replace 741 opamp with some other opam which can work with 3V, and also replace the 4.7V zener with 3 1N4148 diodes in series in the opposite polarity to the zener

      Reply
    • lokesh lokesh says

      Thank you for replying sir..
      but does it supports my 1st conditions
      I.e 1)Disconnect input after (set) full charge.
      if not what simply modifications may required ?

      plz let me know
      thank you..

      Reply
    • Swagatam says

      Yes it will, that's the main purpose of the design

      Reply
  16. sanjay bharvad says

    Hello sir ..

    I want to operate 12vdc relay by short circuit 9000 vdc ..please inform me can I use this circuit..for that and which type of changes I have to do

    Reply
    • Swagatam says

      Hello Sanjay,

      I don't know how you would configure 9kV with a 12v relay, I think that's not possible with the above circuit.

      Reply
  17. Thigiru says

    Hi sanjay bharvad,
    I believe it is possible if you have a step down transformer if it is 50-100HZ ac or high frequency circuit which will step down the 9kv to easy to manage power like 12v. you can then utilize the relay powering circuit from 12v external source and use zener diode to cut out form a cut-off point when the 12v which is directly influenced by the 9kv fluctuates to the level you may want a shut down.
    I have utilized similar circuits in lithium ion short circuit controls for electric cars.

    Reply
  18. Deepak says

    Sir
    I made your short circuit protection circuit it works fine for transformer power supply , if I connect to battery 24v 10Ah ,circuit not working ( when shorting output voitage across relay not fall to zero ,instead huge spark and melting wires) please give any modification or new circuit.sorry for my bad english

    Reply
    • Swag says

      Deepak, it’s because a transformer has limited current which is able to drop, whereas a battery may have relatively huge current which may not drop quickly causing melting of wire.

      add a current limiter in series with the battery, and you will find the system working perfectly. You can do this by adding a low value resistor such as a 2 ohm 5 watt etc or you can calculate it using Ohm’s law

      alternatively you can try the following design which is designed for battery use

      https://www.homemade-circuits.com/2012/04/how-to-make-automotive-electronic-fuse.html

      Reply
      • deepak says

        Thanks Bro, I made your new electronic automotive fuse it works fine,one again thank you for your fast response, I made another circuit 24v battery to 12v 200mA circuit using lm317 adjustable but lc get heated ( some power loss approx 3w as heat) please give any efficent simple circuit for 12v 200mA, thank you.

        Reply
        • Swag says

          My pleasure mate, if you are using any linear IC then it will waste a significant amount of power..there’s no way to avoid this, unless you upgrade it into a buck topology as explained in the following article, you can try it out:

          https://www.homemade-circuits.com/2016/10/lm317-variable-switch-mode-power-supply.html

          Reply
          • deepak says

            Thank you for suggestion Bro. ….

            Reply
          • Deepak says

            Bro another help please, I want to add cheap multimeter ( 2$) as voltmeter for my variable power supply unit , multimeter is 9v battery powered ,I replace it by 7809 ic but while measuring (i.e self powered multimeter) improper reading , please give any simple isolated power source circuit 9v or any suggestion/ideas thank you…

            Reply
            • Swag says

              sure bro, the 7809 should have worked correctly according to me, first confirm whether or not it is giving an accurate 9V without the meter connected…if it is fine, then you can try connecting a high value capacitor across the output and ground of the 7809 and see if that correts the issue….you can try a 1000uF/16V or even higher. alternatively you an simply use your cellphone charger output and use it for powering the meter, it worked great in my meter.

              Reply
  19. Deepak says

    Thanks for your suggestion bro, multimeter power supply 9v by adding capacitor in output is not working on my cheap meter . cell phone charger idea help little bit that is while touching the negative by hand gives proper reading , finally I decided to leave on battery power supply with on/off using relay (one COB multimeter gets defective while measuring voltage more than 3v) . thank you …

    Reply
    • Swag says

      OK, thanks bro, keep up the good work!

      Reply
      • deepak says

        Hai Bro, your help please .
        three dc source with one voltmeter, I need a circuit to measuring voltage of dc source ( common ground) by selecting with one push switch ( 3 way sequential selector switch ) using relay , thank you

        Reply
        • Swag says

          bro, you can try the following concept:

          https://www.homemade-circuits.com/2013/08/single-push-10-step-selector-switch.html

          Reply
        • Deepak says

          Hai bro sorry for disturbing you again and again , I thank you once again for your quick response, I tried sequential push selector switch it works perfect but some delay in selection ,then i changed the capacitor between pin 13 &14 with 0.5uf instead of 1uf it works charmingly thank you ..
          I made variable PSU using lm338t plastic package t220 , when output get shorted ic gets heated instantly with in 4 sec ic gets damaged in min/max output ( but using lm317t long term short circuit and work absolutely perfect without ic gets damage ) even though using proper huge heat sink and fan ,please provide any short circuit protection circuit for variable psu ( but while using lm338k its works fine for some limits time approx 1 to 4 mins , I tried your electronic fuse works perfectly for constant voltage 5 to 33v thank you…

          Reply
          • Swag says

            Bro, LM338 is the 5 amp version of the LM317…and both these ICs are thoroughly protected from overheat and overload situations…..if your LM338 is burning due to overheat that means it is a duplicate IC not original make.

            short circuit protection is absolutely not required for these ICs…you can check the details in the datasheet of the IC.

            Reply
  20. Kesav.N says

    Hai sir….*
    I tried this circuit it’s working well…
    I have one adapter type smps…
    O/p 12v 1.5A …

    Its working good…This smps contains short circuit protection…
    If i short it…smps power led goes OFF…if i un short it…smps power led ON…

    I can’t able to find the circuit diagram…fully molded …
    So pls guide me sir…
    Is there any circuit same like…

    Whenever short happen….smps power led off and in normal condition smps power led ON….

    Pls guide me sir….*

    Reply
    • Swag says

      Hi Kesav, it is normally done through a current sensing resistor at the output side of the SMPS, when current exceeds across this resistor, the feedback optocoupler gets activated which switches OFF the primary side of the smps preventing the short circuit

      Reply
    • Kesav.N says

      Thank u sir
      I need Circuit diagram sir….

      Reply
      • Swag says

        Kesav, you can refer to the following article for all the details:

        https://www.homemade-circuits.com/2015/04/how-to-make-variable-current-smps.html

        Reply
  21. joao says

    Olá Swagatam,

    Este circuito suporta 50v 10A, ou quais modificacoes devo fazer?

    Poderia postar circuito de fonte 50v 10A, quando regulada para 10A a tensao nao cair ou seja estabilizada.

    Reply
    • Swagatam says

      Hi Joao, yes you can use it for 50V 10amp, just add a small value resistor in series with the relay coil, may be a 22 ohm… and make sure the contacts are rated at 20 amps or 15 amps minimum.

      Reply
  22. Joe GP says

    i must admit this took longer than it should have for me to understand, it’s quite a neat idea, but you said “there may be a voltage drop” so what happens if there isn’t one ? like if i’m using a constant voltage power supply ? also what if the voltage drop is not enough ? for example a 12v relay still works at 9.8v (don’t know where it stops) and i’m guessing this doesn’t work at all in a variable power supply.
    Also your relay has to match the voltage output of the power supply, do they make relays that work on 5v ? or 19v ? i’m guessing you are limited to the common ones, like 12v.

    Reply
    • Swagatam says

      Whether it’s a constant voltage or whatever, when there’s a short circuit the supply will drop rapidly towards zero V, and the moment it drops below the holding voltage of the relay, it will trip…so it’s a fool proof design.

      This circuit will work for variable power supplies also, you just have to add the variable circuitry at the “load” side of the design.

      I hope that clears the doubts.

      Reply
      • Joe GP says

        cool, thank you for the quick reply, are the 2 capacitors part of the rectifying circuit or are they for the relay somehow ? if the later, what values would you use for a 12v power supply ?
        The reason i landed on this page was because i was looking for a way to protect my power supply from shorting out because i’m trying to power a reversible DC motor with 2 relays to switch polarity, but if both relays are switched on at the same time by accident they would short the power supply. And because of your design i got the idea that maybe i can cut of the power of one relay while the other one is powered (with the 1st relay), i’m gonna pass the negative of the signal of the 2nd relay through the NC pin of the first (and vice versa), so when one is on the 2nd one cannot turn on, not sure if that will work.

        Reply
        • Swagatam says

          If you use a DPDT relay method, there won’t be any chance of a short circuit as both the contacts would switch together in this case, for the required bidirectional movement.

          DPDT relay motor reverse forward circuit

          Reply
          • Joe GP says

            yeah, in the end i figured that out as well, it’s just that i was also using the relays to turn the motor on and off (this is for my new front gate that i am automating), so the motor going endlessly in one direction or another was not a good thing, but then i remembered that i was gonna install limit switches anyway, so i’ll just use those to turn the motor off at the right time.
            Question: can a relay stay on (latch) forever without breaking ? i’m gonna use the NC loop/side of the relay to close the gate to avoid the relay staying on for a long time.

            Reply
            • Swagatam says

              A relay can get latched typically due to fusing of the contacts, in case the contacts are subjected to higher current than the rated specs. The best way to avoid this is to add a current control stage in between the contacts and the load. A few simple current control stages are explained in the following article which can be tried:

              https://www.homemade-circuits.com/universal-high-watt-led-current-limiter/

              Reply
            • Joe GP says

              by ‘latched’ i meant ‘powered on’ not fused shut, so i was wondering if the device that powers the relays contacts can get worn out for staying on to long, i presume it’s an electromagnet and a spring.
              I’m using a windshield wiper motor (12v@5A) that i think i might be powering with a variable voltage circuit (so i can adjust the speed) that has a constant current function, so i don’t think i will be needing that current limiter, but thanks for the link anyway.

              Reply
              • Swagatam says

                The contacts are coated with special alloys so they are usually very resilient to all forms of wear and tear….

                Reply
            • Joe GP says

              yeah, i know, i saw some say they have silver and such, but i wasn’t asking about the contacts, i was asking about the thing that makes the contacts move.

              Reply
              • Swagatam says

                A relay basically is an electromagnet with a spring loaded magnetic shaft operated by the electromagnet, you can get more details below:

                https://www.homemade-circuits.com/how-a-relay-works-in-circuits-how-to-connect-it/

                Reply
      • manish kumar says

        HI swagatam… i tested this one with 5V relay … it works perfectly when i am using this circuit with normal 5V 2A smps but when i am using this circuit with 5V 60A smps it does not work. i got just big spark when circuit shorts but relay doesn’t trip. what should i do

        Reply
        • Swagatam says

          Hi Manish, to work with 60 amps the relay contact must be rated at 100 amps, otherwise the relay contact will fuse instantly when the output is shorted.

          Reply
  23. reparatou says

    Is there a solution with a transistor to protect the relay coil in case of hight current , and adjustable to set at which amperage the relay cut off !?

    Reply
    • Swagatam says

      relay coil will not get affected with high current, rather it is a high voltage that can damage it. So if the voltage is constant, current won’t matter.

      Reply
  24. Günhan says

    What should be the value of the 2 capacitors in the input for the regulated power supply.

    Reply
    • Swagatam says

      left side is 1000uF, right is 220uF

      Reply
  25. Seun says

    Please how can this circuit work for AC power supply, it is not clear to me, Sir

    Reply
    • Swagatam says

      No, This is recommended only for low-power power supplies…

      Reply
  26. Seun says

    Please how can I extrapolate this circuit to work for shut down pin on inverter module.

    Reply
    • Swagatam says

      Which IC are you using for the inverter?

      Reply
      • Seun says

        Sg3524 Ic

        Reply
        • Swagatam says

          You can refer to the following post and see how the feedback for the over voltage and over current are included in it: Over voltage cut off at pin1, over current cut off at pin4/5

          https://www.homemade-circuits.com/inverter-circuit-with-feedback-control/

          Reply
  27. Ömer Faruk says

    Have a nice day bro. I made a spms circuit that produces a constant output of 74 volts from the voltage I get from your 220 volt network. What can I do to protect my mosfets in my circuit from overcurrent. I trigger my mosfets with a pwm signal. I do this triggering with 3 trigger transformers. I have a 25 khz voltage reducing transformer. How do I make a short circuit for this spm circuit. I am waiting for your help. Thank you in advance.

    Reply
    • Swagatam says

      Hello, have you used any IC based controller in the SMPS, if yes then you can put a series resistor with the MOSFET source, and use the voltage drop across this resistor with the shut down pin of the IC, during an over current.

      Reply

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