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Are you looking for free circuits, ideas and solutions? Are you interested in getting personalized help regarding an electronic circuit project which you perhaps couldn't grasp correctly? Feel absolutely free to contact me through the comment box below the articles for getting quick solutions to your queries.

If you need a customized design for a specific application you can explain it through comments, I'll try my best to get it done for you absolutely FREE!

You may also contact me through the following means, although the ideal platform for interacting is the comment box, since it allows other visitors also to benefit and participate in the discussion.


hitman2008 @ live.in

homemadecircuits @ gmail.com

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147 thoughts on “Contact”

  1. Hi! Mr. Swagatam

    OK, I see your concern that you are busy.
    I am very thankful that you allow me to use your design. And I also very pleased for your deep kindness that you are also interested to help me in technical matters.
    I am preparing things and thank you again for your great wish that I will be success.

    with Best Regards!!

  2. Dear Swag, I’m Claudio… ;-)… excuse me… could you imagine other features of inductor?… furthermore… someone thinks that the duty cycle should be in microsec order… what do you think about a ne555 flip-flop with 2n3055 to bear the high extracurrent? Bye

    • Hi Claudio 😉 Could you please tell me which schematic or concept are you referring to? I’ll try to answer to your query…

      • Hi Swag..;-)… I’m sorry… I’m referring to a simple schematic about the «cold electricity»… in the free energy section…

        • OK got it, yes you can try a IC 555 based oscillator for creating the collapsing the magnetic field, and subsequently cold electricity, however I am not sure what frequency would be ideal for this operation…

            • I can help only once I test these concepts practically, I may do it sometime soon and will update the results here for sure…

  3. Hi! Mr. Swagatam
    I am Dawit and Electrical Engineer
    I have been working in different industries by giving maintenance for different electrical control system. Now when I come with your site and see your creative works I realy appreciated you and I have been myself ignited to such works and turn them to a business in home based. of course, I have not yet facilities for such production. What do you suggest me to have, and toward degree would you cooperate me to such manufacturing and turn them to business if it is your interest to work with your design works. In our country, Ethiopia, a lot of your works have business. for example home air ionizer would have a lot business In our gas polluted town Addis Ababa.
    Thank you in advance for your attention

    • Hi Dawit,

      I appreciate your offer and enthusiasm, you can feel free to use my designs for manufacturing and doing business in your country, however I personally wouldn’t be able to cooperate in this venture with you, because I am already too busy with many assignments here, so getting involved with any external business would be difficult.

      Anyway I Wish you all the success! Let me know if you need any help regarding any technical matters, I’ll be happy to help!

  4. Dear Swag,
    Please help design for me an instructable UNIVERSAL SMPS for High Power Amplifier voltage ranging from +/- 50v to +/-100v Dc.

    • Dear Erntec, I am sorry I am not good with designing SMPS circuits, therefore presently it won’t be possible for me to help you in this regard..

  5. Thank you very much for replying sir.
    Is ok if you can give me the digital clock without the date, But will the time be set to work both French and English time?
    As for the link you sent, thanks very much but now my question is, if i assemble the circuit, can it be connected to the CDI as it is then the car speed be set to certain frequency? if yes then good, it will even be good because i can use one of the leds to energize a transistor as a switch then start to think of what to do next…
    i look forward to read from you and thanks a lot.

  6. Dear sir.
    Hope all is well with you, i must take my time to first of all appreciate all your good efforts and help you offer from your website,
    i have enjoyed a lot from your website, but i came accross a project from your website and i wonder if you can help do some modifications so that i can use it as my test projects coming up, i am basic but to build any circuit i have no problems doing that.
    i came accross a circuite under auto-mobile projects, the car speed indicator, dear sir, is there any way you can modify the circuit in such a way that, when the CDI gives signal about you over speeding, a circuit automatically stops your engine for at least 5minutes?

    Then as for the other help i will ask you is that, i am in need of a digital clock schematic that has date/month and time, if the digital clock can indicate time in French and English it would be excelent.
    thanks for your understandings and i will be looking forward to be reading from you.

    • Thank you Nkwenti,

      I am sorry I do not have the digital clock circuit with month date, but you can perhaps find through a Google search.

      For the car speedometer cDI controller you could try the following concept:


      From the 10th LED or 9th LED of LM3915, an IC 555 monostable could be added whose output could be integrated with the CDI for stopping it as soon as the sequence reached these LEDs.

      You can first verify the above circuit then I will proceed and tell you how to configure the IC 555 monostable.

  7. Thank you very much. I’ll try it out a.s.a.p.
    What is the difference in power consumption between the first and second iteration of this design?
    I’m probably being a pain, but can you give a breadboard illustration of both circuits. Or maybe a link to a VBB design.

    • You are welcome Andreas.

      I won’t recommend a breadboard assembly. This must be firmly assembled and tested on a veroboard, by soldering.

      Secondly the resistors involved with the LDR transistor will require some tweaked until the desired results are achieved.
      This circuit will not consume anything while it is in the standby mode…

      • Thank you, I have made the circuit with both designs….555 and bjt, had to play around a lot to get both working because of the difference in ldr’s. I added a cell phone to the setup with a relay connected to the dial button. Now I want to add a power failure backup utilising the cell phone’s own battery and over charge protection and also add a comparator circuit to both ldr’s, so a would be thief cannot just shine his own laser to disable the system.
        I would very much appreciate if you could maybe start a new post incorporating all these ideas into one circuit. I see you have a few other circuits that use some of these individually, but not one “fully incorporated” system.
        Again, thank you very much for you patience and all your help.

          • Thank you, you have been soooooooo much help.
            I looked at the circuit you suggested sorry….I struggle a bit still with learning electronics…..how do I tie this into the 555 circuit, does pin 1 and 7 of the op amps go to pin 2 of the 555 as trigger?

            • You are welcome Andreas, sorry I did not get, which IC 555 stage are you referring to? the suggested LM324 will not require any other circuit, it has two LDRs which can be used with the laser for getting a foolproof implementation.

  8. Hi Swagatam,

    I made your smart alarm system that a guy from South Africa proposed recently and I really love the idea. Btw, i’m also from South Africa slightsmile emoticon ( the laser alarm system with two ldr’s,
    “Smart Laser Alarm Protection Circuit using IC 555”)
    I was wondering if you would be able to expand on the idea as follows :

    I would like for the system to have a back up battery, so that it is tamper proof and also wanted to know if the same result could somehow be achieved without using the 555 as it is very power hungry.
    Also, if you could incorporate a potentiometer or something so that the light intensity can be adjusted on the ldr’s. I am planning on putting mirrors around an area of 4 meters by 2 meters square for the system and the laser light is quite diminished by the time it has gone around that whole area.

    If possible, could you also let me know what a “kit” like this would cost.

    (Sent you message on Facebook, not sure if you got it, so sorry if i’m repeating the same 😉 )

    • Hi Andreas, I am glad you could make the project successfully.

      I have noted the improvements suggested by you, and will try to update the article with the modified design soon.

      • Thank you 🙂
        Another question, if i may…..
        Could one include various RC combinations and toggle them with a sweeper switch? I.e. 10 second RC combination, 30 second and 1 minute on a 3 pin sweeper switch so that you can choose the duration that the alarm will sound?

        Also, which changes would one have to make to include a gsm combination as in one of your other posts or can one just tie the one you made in on the pin three of this circuit?

        Again……Thank you very much for your help and dedication with this site. YOU ROCK!!!!!!

  9. Hello Sir,
    Hope you will be good.
    I am a big follower of you, will you guide me how i design 2.5kva gasoline generator AVR or please share if you have any circuit related portable generator AVR.
    Waiting for your guidance.

    • Thank you Waseem,

      Although I am not sure how to control a generator output, it may be perhaps done by controlling the CDI ignition rate through a feedback from the generator output voltage…if possible I may present the concept as a new article.

  10. sir how to dim and use 6 or 12 volt batery to drive 50 watt led ( using TL494) thankyou for your attention sorry my bad english.

  11. Hello swag. I am a regular visitor of you blog and it is awesome.
    I am trying to make a modified sine wave inverter. I have one unused raspberry pi 3, so I though of using it for generating pwm signal and use it with a square wave inverter. Will it work?

  12. Hello!
    First of all I’ll appericiate you for your work.you are doing very good job…keep i up!

    Second I need a circuit which will need the following paramters.
    1. Run the motor after specific interval e.g after each hour.
    2. Motor should run off when there motor is not supplying water in upper tank (means dry run protection in upper tank.)
    3. If upper tank is full,motor should not run.
    4. If there is high or low voltages from a certain voltages than motor should not run.
    5. If there is power failure during startup, than motor should start after delaying some certain time when power restores(delay startup).

    I hope you can help me on this.

    Thanks in advance.

    • All these circuits are already published in my website in separate articles, you can search these articles and join them together for fulfilling the specified needs…

      • Thanks for your reply!

        I am very initial level hobbiest and could not enough knowledge to merge different circuits according to my requirement. Kindly guide me some so I can up track on my requirements. Or atleast give me list of you articles with guaidence to join these circuits which you think that can fulfills my requirement.

        You are doing very good work, and your website lead me to stay on from yesterday and i have bookmarked your website.

  13. to u and yr family.
    Sr i want to glow up 7000 to 8000 leds with 220 v ac and want them just blinking.
    Kindly guide and help me giving a appropriate ckt.

    Thanks and best regards in advance

  14. Hello Sir,
    My name is Jameel Ahmed
    my english is not good.
    I want a Electricity Power Saver circuit for Home Application for saving power consumption,

  15. hello sir
    sir, In my flat there is a problem of light cutoff when alternating current gone. Our building's gate keeper start generator and we have to switch off all extra load (e.g fridge, a.c etc). There is nothing to notify when light comes again. Is their possible to detect generator current/voltage/freq. or alternating current/voltage/freq. . Please help me sir
    my gmail id is shivamchauhan20sep@gmail.com

  16. Hello sir

    I am chetan from karnataka
    Sir is there any circutes regarding monkey repeller
    kindly help me about this.

  17. Hello sir,

    I want to make 3RCA TO 6RCA Female cable and 3RCA TO 3RCA+RJ45 Female cable. Will you please provide me circuit for it. Pls do the needful


  18. Hello Swagatam,

    I would like to meet you and discuss projects for welding machine. I am Mumbai based. My phone – 9820212263.

    Any time will be convenient to me. Please reply.

    Much awaiting,

  19. HI Sir
    Thanks for this valuable blog.
    can you post a brushed DC motor speed controller circuit up to 10 HP

  20. Hello Sir

    Do you have schematic of electric bike especially brushless motor and controller , how can i make a ebike for my self


  21. I want to make a led lighting circuit which will show the blood flow of human heart including open close indication of valve. Can you help me to do this project providing circuit diagram and details . I want to use 230 v ac supply for input. Kindly reply me in my email id uniqash@gmail.com.

  22. i like to build led sign but i have small knowlege with the pic16F And attiny 2313 That i try to study them. I asked my friend to help me because he has many knowlege in electronique than me.
    My dream is to drive many leds on one pin µcontroller. But i can't make it now.
    Perhaps swagatam will help me to solve this problem,thanks a lot for your good site.

  23. Hi Swagatam,
    This is RSBirman.
    Do you have any circuit which indicates open earth and has a NO/NC relay contacts which can trip the contactor if the earth is not connected and this will avoid the instrument from getting on.
    The sensitivity should be adjustable.

  24. Hi,
    I recently by mistake bought LED bulb(Great Value) from South America which is 110V. But I want 220V LED Bulb as I'm in Sri Lanka. Now I'm trying to do some modification on LED driver. Please help me to do this & Fix this bulb to use from 220V. Which parts need to change on the driver ?

  25. 220v Ac COB 5w(5A) Led is getting excessive heat after connection. Also not lasting. How can I solve this problem???

  26. Hi Swagatam,

    I need a countdown timer with a relay which can be set to 1 to 5 minutes.
    I would like the timer to show the preset time on 7 segments e.g. 3 min. = 180 or 3.00
    When the time counts the 7 segments shall show the remaining time.
    When the time is up the relay must switch off.
    I don’t have Arduino and no skills in PIC programming yet.

    Can you help me out with a circuit / schematic?

    Thank you in advance,

  27. Dear Mr. Swagatam Majumdar,

    My name is Srinivas Chakravarthi & I am working on Electro-Chemical project, for my lab work, I need an Universal Power Supply (AC/DC) with variable Voltage, variable Current & Time controlled Polarity Switching.

    My requirements are:

    Variable Voltage 0-100 (V),

    Variable Current 0-100 (A),

    AC or

    DC with or without polarity Switching (1 to 10 minutes variable).

    If you can make one such universal power supply unit, I shall be very much grateful to you.

    Thanks & Regards,

    P.Srinivas Chakravarthi.

  28. Dear Mr.Majumdar, I am Kamal Kumar from Chennai.
    I hope to find a good circuit for a battery eliminator with output dc power ranging from 1.5 to 12 or 15V and with its PCB design etc. can you kindly give me the same I will be very thankfull. I have searched every where on the internet but nothing seems good for what I am looking for. Thanks in anticipation.

  29. Hi Swagatam I am a fan of ur work..
    I need a help.
    My laptop and mobile over charges each night.
    I want to creat a circuit that can start supply at desired time later i.e that 2 or 3 or 4 hrs later and supply should should be ON again for desired time .
    I would have to enter how much time later Supply will be on and off..

    Thnx man, Your work is really great.

    Please inform me if you are working on this project.

  30. Hello Swagatam. I was thinking about put a sensor on the gasoline line from my motorcycle tank, near top, between the tank and the carburetor, that would consist of a pair of (innox?) leads like some mm separated from each other. This would detect the electrical conductivity inside the line, in direct contact with the fuel and while there is gasoline wetting it, it would output 0 volts, and when not (i.e. gasoline is ended and the line is becoming empty from the top), it would output positive (12v?) so I could light a warning light on the dashboard to avoid getting engine cut on a sudden. I can quickly turn the valve from to reserve position in this case. So when sensor wet, 0V(0); sensor "dry" 12V (1). What do you think? Thanks Sir.

  31. Hello,

    I love your website! I was looking at your circuit "twin or split battery charger" and I don’t see a value for the resistor between pins 1 &3, 7&5 for the LM358 is it 1k? I’m going to make a printed circuit board of this design using photo etching.

    My goal is to build a circuit that will charge one battery while running off another battery and when the run battery falls to a certain voltage level, switch to a charged battery. I am not looking to make an over-unity device; I am interested in experimenting with energy recovery to create long pulse motor run times. I expect the system to eventually die out but I want to see how long that process will take using air coils and back emf harvesting.

    Would this circuit work if I replace the batteries with two 100F 2.7v supercaps? Since the caps charge faster than lead acid batteries, this may help the efficiency of energy recovery during the run time windows.

    I love building things and your awesome ability to design such cool circuits makes people like myself enjoy hours of building these cool circuits and watching them come to life.

  32. Dear sir, i am very fond of u, by u i love electronics, u r really genius, u made electronics very simple.
    Sir i would like to request clap switch and timer circuit for 8 volts led bulb which remain on for a long time
    Please help me to solve the circuit.
    Thanking u

  33. hello sir,

    i really liked the way you reply to queries and your good heart of sharing. May God bless you.

    please sir, am working on a project titled "remote controlled DUAL BAND MOBILE PHONE JAMMER"
    i hae tried searching for a working circuit diagram but hae been able to find one. please i will appreciate it if you could be of help. thank


  34. Hi Mate,

    I am designing a Spot welder Controller with an Arduino and there is a need for a in rush current limiter. Would it possible for you to design the "In-rush-Current-limiter" i have read that it can be done in several ways. I will be using this to drive a Microwave oven transformer modified by rewiring the secondary to 3 turns of 3AWG wire for spot welding 18650 cells.

  35. Hi Swatagam!
    I would like to know if you could make a circuit that can activate a 12V 600ma stepper motor for 10 or 20 seconds every 3 hours or so. is that posible?
    Kind Regards,
    David Montenegro

  36. Sir, plz help me in making a circuit with following details. A 12 V relay is to be connected such that a momentary push switch turns it on BUT but after release of switch the the relay should not turn off immediately, rather it should turn off after some time say roughly 1minute. Thanks

  37. Hi I need a Nokia Mobile battery( 3.7v) driven simple Bluetooth stereo amplifier circuit diagram.Please develop it.

  38. Sir your projects are really great but I am a student of class 10 sir can you help me with a idea of creating a project for science expo.

  39. i need to assemble variable frequency(a pot can be use on output of 555 for variable amplitude) square wave funtion generator with frequenciies 1 Hz to 1MHz ,flexibility to vary amplitude of output ,555 should be used in astable mode and axact 50% duty cycle can be obtained on output plz help me sir in desining the above circiut i will be highly thankful to you

  40. Dear swagtom sir! I have heard that we can communicate by intercom using main ac power line home to home , i need communicate with my friend , there is about 3km-4km between our houses, but our ac power line is same, can you give me circuit communicate with him? please!

  41. dear sir, i will enough grateful to if you can provide me the complete circuit for e rikshaw with solar system alongwith complete electronic component value, please send it to amit46vm@yahoo.com/gmail.com

  42. This is just a simple question :
    Can i use a lower Ah battery charger(say 20,30)to charge a higher Ah battery ie 110Ah?What are the consequences?
    What is the difference in the charger circuit in both case?

  43. Hello Sir

    This Is Aravind Sir

    I Like To Know How To Make A Transformer And Its Calculation And I Google It But I Cant Find The Proper Calculation Method And I Find Around 7 Method Of Calculation But Its Not Proper With Manufactures Standard And Can You Please Help Me To Know It Sir

    Thanks You

  44. hi sir i can you please design a circuit which will output 9v dc from a 12v battery efficiently . it can be by using ic 555. this will be use to run a rc toy car using 0.8A max. if possible can it be a variable output voltage dc. i have a 2n3055 transitor ,MJ11015 TRANSISTOR.

  45. hello sir ,this is vinod from mussoorie near dehradun.i am not an engineering student,but i have lot of interest to make different electronic items . sir i would like to know that is it possible to use usb drive in normal tv without hdmi and usb port, by putting some type of converter in between them.if yes please tell me the circuit diagram .

  46. I'm trying to make a circuit that will turn on them off a pair of 12v pumps in sort of a heart beat pattern, repeatedly. U haven't come closer. Any way you could help me with this?

  47. I'm trying to make a circuit that will turn on them off a pair of 12v pumps in sort of a heart beat pattern, repeatedly. U haven't come closer. Any way you could help me with this?

  48. Hi again ,
    thank you for all help you providing 🙂

    i think this circuit could be useful and after searching many sites i could not found a good circuit !!!

    i need a circuit which get 2 input for 12 volt DC 5 AMP power supply , and give one them in output ,
    if primary power supply fails , secondary power supply take the action , something like Redundant Power Supply,

    to my knowledge we could do it in 2 way
    1- ORing Diodes

    would you please design a circuit like that ?

  49. hello sir

    I am zulfiqar
    I want to make a project which control the the lights, fans (and other appliances that are used in one room)
    from the another room .
    I have to use two controlller and a single wire communication between them

    If i press light button light should be on of other room and i press fan button fan sholud be on
    I have to controll the 8 things using two controllers

    Kindly help me in makin my project I will be greatfull to you

  50. Dear Swagatam,
    Greetings of the day.
    Can you send me the link of circuits which uses remote bell to energise a relay, making it wireless relay activator.

  51. hello sir this is shubham from maharashtra india,
    Sir my question is how general sine wave of a oscillator (consider colpits or hartly oscillator is differ from the sine wave which we use to power all AC powered equipment's. Is this possible that we can make a inverter circuit by using hartly or colpits oscillator, if yes then how? Please give me reply sir. Thanking you

  52. It looks good that you are doing lots of hard work for all your projects
    But i here wanted to you to suggest you to make your website more ineteractive &attractive for the user
    becoz if your site will be interactive then people will often like to keep on visiting it's an important aspect with your
    toil hard work . Thank U

  53. hello Swagatam can you help me with a power supply drawing for a grow led light?
    direct 220 to a chain of 3 watt led ratio 4 red 1 blue
    best regards walter

  54. Hello Sir
    I am working on a project of designing 40W/15V SMPS. I have all schematics of 65W and triple output of 5V, 15V,-15V SMPS. for this SMPS feedback circuit is designed for 5V output. I want design Feedback circuit for 15V output. can you explain what changes i have to make for this and how would i chose parameters for feedback circuit. I am using NCP1203 for switching. My emailid is shefalip.06@gmail.com. Please sir send me your email id so that i could send you all schematics.

  55. hello friend, I am passionate about electronics and also am one of your admirers around the world. I wonder if you have some scheme of some electronic circuit able to control equipment from a distance, via mobile phone, gps, etc, because we need a device on and off the distance that can be locked. If you already have some mounted, I am interested in buying from you if it is not too high. I appreciate the attention, any questions can explain more detailed via Skype If you possess. thank you

  56. hello friend, I am passionate about electronics and also am one of your admirers around the world. I wonder if you have some scheme of some electronic circuit able to control equipment from a distance, via mobile phone, gps, etc, because we need a device on and off the distance that can be locked. If you already have some mounted, I am interested in buying from you if it is not too high. I appreciate the attention, any questions can explain more detailed via Skype If you possess. thank you

  57. Hi Swagatam,

    Nice blog you have, I am actually looking for a transformer less power supply something like mobile chargers but i want to operate relay using it, could you please help me with this. Do you know any place from where i can order these circuits or if i can myself make it at home.
    Any help will be appreciated.

    Thanks & Regards,
    Saiyad Rasikh

  58. Dear Swagatam,
    Searching for small invertor circuits i reached this website , i got a 100 watt invertor circuit diagram on this website which uses
    4047ic and irfz44n mosfet and successfully got running invertor thank you very much for this.
    now on the same lines using this same 4047ic circuit i was trying to develop a smps with higher frequency unlike 50hz above
    this time using irf840 mosfet and ferrite core of size 35mmX28mmX12mm primary winding of 300turns and seconday 18turns
    i am facing the problem of irf840 getting hot quickly and also this ferrite core transformer making vibrating sound squeaking sound of
    the high frequency of about 12khz to 18khz , actually i am not electronic educated but mechanical engg but having very much interest in developing and trying self useful electronic circuits
    kindly help me understand what makes mosfet to go hot quickly and transformer making vibrating squeaking sound

  59. Sir i am omkar pawaskar
    i want to make a wind based mobile charger which can charge my mobile when i ride my bike
    m trying this from long but have failed pls guide

    omkar pawaskar

  60. hello sir,
    i want to make IR based fan regulator with 5 speed fan control it should not work like dimmer as dimmer based regulator make fans to create noise on slow speed. can u plz help me

  61. Hi Swagatam,
    I want to design DC-DC converter using OP-AMP. Specification is 12 VDC input and 48 V DC output. Can you please give some related circuits

  62. Hi swag, do you know Grid Tie Inverter with Limiter? Can you please design me a limiter that I can connect to any ordinary Grid Tie Inverter? Thanks

  63. Hello Andre,

    I'll try to design the circuit for you soon and let you know, by the way please do not post on this page as it has stopped responding to comment postings

  64. Hello Swagatam,
    I was wondering if you could possibly assist me. on the blogs I have seen some diagrams for simple variable power supplies. Firstly I know very little about electronics, but with a shopping list and a diagram I am sure I would be okay. I would like to build a simple variable power supply with an input of 220/240 volt ac and an output variable voltage of approx. 1.5V to approx. 15V and a variable output current of up to approx. 100A. I have started zinc electroplating as a hobby (have sweaty hands and want to protect all my tools) the chemical company gave me these as a more or less dependant on my zinc plating bath size. At the moment the little 6V 8A Ryobi battery charger works for a few minutes, overheats and cuts out till it cools down again. I would really appreciate any assistance you could give me on this.
    Many thanks

  65. Dear Mr. Swagatam,

    Happy New Year 2015……
    GOD Bless You…….

    I come from Indonesia…
    I am Great fan of you, I like to go through your blogs and also the comments.

    So finally I got inspired and start to work on very simple requirement of mine.

    Please Help me Sir,
    so I Need Timer 3 Hour intervals and now I Have Schematics Two Hours….Can you help us to change its?

    Uploading the circuit diagram is not possible here so I have sent it via your email address hitman2008@live.in and homemadecircuits@gmail.com

    Best Regards,

  66. Dear Swagatam,
    I want to design DC to DC converter, Like 18 V from two battery 9V in series, by using I 200 or LM7809 to get 9 Volt with 600 mA, I can get the 9V from regulator, but I can not get 600 mA, How can I get the 600 mA.
    Thank you

  67. Hi,

    Hope you are fine. 🙂

    The purpose of writing here is to share with you an idea of a project – to design a "heart rate monitor alarm" which can be made by using commonly available low cost components and which will produce an audible alarm whenever the pulse rate of anyone is found to be abnormal. It should meet the following conditions as well:

    a. Compact and light weight, therefore portable
    b. Consume minimum power, therefore should run 24×7 for a month or two from a couple of AA batteries or a 9 volt pack
    c. Should be fairly accurate in it's performance

    I know there are many such circuits available on the net but their performance and reliability are questionable. The unit can be very useful especially for elderly people (with / without a heart disease), for patients who are bed ridden and so on. When the heart either beats at a rate higher/lower than a set average threshold value, the alarm will sound loudly enough to alert people around the patient.

    I hope that my proposal is clear to you. However, if you have any doubt, please drop me an e-mail.

    Thank you,
    Kind regards,
    Raj Kumar Mukherji

  68. Sir, Can you provide me with a circuit to scare birds circling around our gatherings in park.
    Thanks in advance.

  69. This page is not responding to comments, however I have read your comment which you have posted, I'll do the required corrections in the DRL circuit.

  70. Hi,
    I need a circuit to start an Electric Generator automatically when power is failure, and then stop it when main power is ON. can you help me? is there any idea based on 555 timer sircuit using SPDT relay.I have a 3KV electric generator with selfstart option.

  71. Hi,
    could you please publish 3 phase regulator rectifier circuit for motorcycle . thank you

  72. Hello sir,
    I need a circuit which will make 12 volt relay initially On, as soon as I trigger, relay should get OFF until I restart the hole circuit. Relay should stay OFF irrespective of thereafter triggering.

  73. hi Swagatam
    i have an ic voice recorder model vr330
    at first it was working well
    recently it always shut off "battery low" i replaced the battery but no success.. i used lm1117 3.3v but also the same result.. it always tell low battery and shut down..
    i checked every single item on the board but didnt find any item harmed
    is there any chance that i could fix it ?
    thank you

  74. Hello Sir Can you tell me how many 1 watt LED I can use in series on 12v 500mAh charger usually use for modems etc. Do I need any resistor to do such. Regards

  75. Hi i have a request :D, if it's possible. a circuit for a DRL (day running light.) made with 10 LED white, the circuit for led must be with impulse (impulse control) a potentiometer for frequence control , frequence between (i can see the led blink -and- over eyes can percept). if you have a idee. V=12 V

  76. Sir how can i send you a circuit in your email id or what…. I want to send a circuit …..me bhanu

  77. Hello sir, I really need your help. Any suggestion of a circuit or electronics components I’ll be needed to build a circuit for an automated conveyor that could detect if the boxes are large, medium or small and sorted them to 3 different directions. The size of the conveyor is 10 inch by 18 inch. By the way sir I’m from Philippines and I’ am a currently second year college student taking up Electronics and communication engineering, and that project was my final requirements for industrial electronics sir. I really hope you’ll respond as soon as you saw this. Big thanks to you sir. Have a good day 

  78. Hello sir.
    I want to make simple SMPS welding machine for my personnel use .if u have any complete circuit and design please help me.

  79. The circuit presented in the following link is correct and will surely work, although it's not yet tested by me, but I am sure about it.


  80. I made the circuit "Simple Door Bell Timer, with Adjustable Timing Facility" but it is not working. A few days ago I saw the same circuit in your site with some modification using bel8550 and 8050 transistors with some change. I am confuse that which one is correct and tested o.k. Please clarrify.

  81. Hello Swagatam –

    Your site is very good. Specially for those interested in Electronics & in Building. I have a Little Problem as I am just an electronic hobbyist. I am not aware much about the Components. Can make a Article page on this site explaining in details how to use PCB's, Correct way of connecting LED, Resisters, Diode's, Color Coding of Diodes, etc.

    This will help a New Hobbyist to learn a few circuits building. There are many Ready to build kits in the market and we get all the parts mentioned in your blog easily but are struck when we have to make the connections as we get confused as to which wire has to be connected to Positive point or Negative Point. If we connect it wrongly the project may fail and if the project involves main current then the damage may be Great.

    Hope you get my point.

    Thanks & Regards

  82. Can you post new like Led Propeller Clock or Rotating Led Globe it is difficult but very interesting…….

  83. Hello Sir
    I want to built static voltage stablizer using IGBT, can you help me with some proteus simulation circuits and codes

  84. Dear Mr Swagatam, i am an electronics hobbyist and followed your work on this site for some time now. I have learned many things from it and i like to thank you for that. For my next project i like to make an inverter with parts salvaged from obsolete ups's. I have a 2kva transformer, a print board with 16 mosfets PN80NE0 full bridge driven by 2 ic's IR2110. Do you have a circuit with load dependent correction for me that i can use?

    Thanks in advance
    Best regards,

  85. helow sirr ……I hav got a project on single phase transformer……if u don't mind den can u plz say me abt its construction n components to required to build a one phase transformer……my gmail is pawan.singh2069@ gmail.com

  86. hello sir iam basha your projects most sinceyarli warking
    your 2 to 5 kms fm transmitar project i like it sir so you made this project my adress send me sir this project money i paying sir
    please made and send me sir thanq


  88. hello sir,
    i want to make one miniature electic stove so please give me some tips to make it….
    waiting for your reply….

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