Feed back


  1. M.Sankara Sarma says….Your site looks great!
  2. Rohit Jain says …..Your site looks awesome!
  3. Edi says ….hi…..im fr indonesia….i love most ur design i hope you have another one that easy to DIY for beginer…
  4. Neon writes ….Yahoo !! Yahoo!!!! Who said that- transformerless power supply cann’t provide more than 100mA current within less cost !! This circuit is providing 250mA current . Sir, you have made it successfully . Thanks for your excellent invention . You are really outstanding
  5. Anil kumar says …. i need ur valuable suggessions in electronics
  6. Gopalakrishna from Hyderabad writes …. It is higly educative. The beauty of the art of your presentation is that it is undestandable even to non technical people like me. Thank you very much. Best wishes.
  7. Neon writes ….Sir, Thanks a lot for presenting such kind of useful circuit . Between the Battery Status Indicator & Battery over discharge Indicator, I Like this Battery Status Indicator circuits most . Because- It doesn’t need any switch and will not take any current from battery until it reaches it’s specific value . And it takes the lowest cost to build . Thanks again for this circuit .
  8. Hb writes ….Was just surfing the net for circuits and got on to this post..I must say i have never understood any transformerless supply circuits ever…but in this post the whole concept got clear and now i may make one by the guidance of this post…Thank you for such a deep and proper explanation which is in simple language
  9. Aman says …..Really, very STRANGE and EXTREAM.However, I’m kind of a newbie in the field, but I’ve got a project that’s ordered by one ofmy relatives.
  10. Passcod says ….Hi, that’s a great site, which gives plenty of stuff to do in my free time.
  11. Hiran says …..thank u verymuch….actually its my miniproject sir i need to give documentation for it can u please give circuit explanation,datasheets,specifications,APPLICATIONS(other than mobile charger….
  12. Chinmoy Mithra says … The FET preamp circuit by Mr.D.Mohan Kumar is interesting and a bit unconventional. Though I have not yet built or tried the circuit, I am sure it will work. Yet I have a couple of points to mention about the circuit…
  13. Aneel says …..hello i am a student of electronic engineering in 2nd year.
  14. i am willing to join your group so, send me free differnt and latest electronic circuit diagrams.very thankful to you
  15. Robert Luijiano says …This is a great article, I will bookmark it and use it as material at school.
  16. Haiden says …Sir I’m a Computer Engineering Student and I have Implemented your Shadow Alarm Design in my Basic Electronics Project. As you know that i have to prove the Alarm by mathematically, I have done the calculations when the photo diode is with out shadow & it’s approximately equal to the measured readings but I ‘m having some difficulties in the calculations when the shadow appears on the photo diode because I can’t figure it out how to calculate please help me on that because I have to submit & give viva on 24th April 2010.
  17. Neethu says …I am final year student ece department. i need an circuit of shadow gate system actually i want to do an project based on security system in museum.All the gate should access according to the shadow or light in the museum so that when thiefs shadow or light generates then all gates should automatically close and alarm rings.and when the unit or thing is taken from its actual place then light should generate.sir please give your opinion about the project and circuit diagram and description about the project
  18. Tact Maniac says ….We are looking forward to present a paper to IEEE Indian council. We are not familiar with IEEE standard of papers. We would be obliged to seek some guidance regarding this on  how to start a paper and a note on present innovative topics that can be presented.
  19. Barbara Young from Florida says …Hi, My name is Barbara and I’m one of your readers.I’d like to thank you for the excellent information I’ve found on electroschematics.com, it’s one of my favorite readings on the web.I have 30 years and live in Florida where I have the passion to share with family and friends tips to help them save energy to lower pollution and CO2 emissions.
  20. I figured you might be interested in including a guest article
  21. for electroschematics.com about the most common questions related to
  22. solar energy and how to lower energy costs.
  23. Arun Kakkar from Uttarakhand says ….hello sir i am student of GBPUA&T,pantnagar and i am in urgent need of these reports  for my presentation on this subject .could u please give me the full details of mobile bug including the report, datasheets n all available diagrams of pins.its very urgent .so i will be highly gratful if u cud send them as early as possible..
  24. Nishath Chennappa from Andhra says…sir i am enthusiastic in knowing about the efficiency and improving pv cells  (by application of nano technology )  can please guide me or refer to some trusted site….please
  25. Pramod Thakur says …  i am a studying software developing.That was a great post i liked it . I am not in a electronic field rather i am an in IT field but i love electronic and mechanical  things very i try to make new things…….
  26. Jagadeesh kumar from Coimatore says….I read your post  on bionics.Its
  27. nice and great. please post more recent topics.thanks.
  28. Fathima from Jordan says …..may i ask you helping?have final graduated project in my university , it’s name Mobile phone jammer and sniffer.and i want to collect and understand some notes in sniffer (detecter) than give alarm when someone try to make calls …..
  29. Nelson Lamahewa says…… Dear Mr Mohan Kumar,
  30. I will be thankful to you if you kindly publish a fence charger circuit diagram with transformer details. input should be 12 v dc output should be more than 5kv
  31. Nandini NJ says …..I checked the website. It is a useful site, keep going, all the very best.
  32. Susan says ….thanks for the informative site
  33. Sensor Faucet says …Nice infos for begineers. Thanks.
  34. Anand says….superb collections. i want more like this
  35. Manu alld says ….i am so impressed by your projects, thanks for devoting your precious time.
  36. Nelson Lamahewa says…..I will be thankful to you if you kindly publish a fence charger circuit diagram with transformer details.
  37. Ed says ….Thank you for all the fine circuits, you have sent and kept us all up to date,…..I have been downloading them to my files,BUT a big THANK YOU D.Mohankumar
  38. Deven said…..The article is really impressive. I’m very thankful with you.I’m planning to make an inverter as my final year project for B.E. Could you write some reference books title?
  39. Adenele Debo says …Thank u very much for all your advice,pls can you help me out with 500va inverter design calculations?
  40. Tahir says…Sir, your way of defining is really impressive.Is it possible for you to explain how to choose Transformer size for diffrent capacity Inverters.
  41. Mr. Marian from electroschematics.com, says …..I want to thank to our current Author D.MOHAN KUMAR which is doing a great job on the website helping people around the world by publishing great electronic circuits with detailed informations.
  42. Deven says…..Sir, could you write about PWM inverter in such impressive way. I would be very thankful to you. I’ve scanned a number books related to power electronics but could not understand till date. I’m very hungry to know the principle.
  43. Arushit Mudgal says………. I am a student studying in VIIIth standard and i want you to please tell me for my beginners project,what should it be?Plz sir dont think i will be not knowing anything but i know all about transistors,capacitors,resistors which are important
  44. Akshata from Mangalore says ….hello sir.. im akshatha, engg student from Mangalore …I am doing a project on car anti theft guard. So I need your help sir.. if you  have details of this project kindly pls send me some information…
  45. Karthik says… Sir I want full details about standby power loss preventer.  Where should  6V relay to be connected
  46. Soumya says …Hi sir I am Sowmya . I am a MA student from mangalore. I took mobile bug as MA mini project. But sir i dont have full details about this project so please can u send me d full details about this project
  47. Dee says …… hi there, what a great article! covers just about everything. well written and very clear. thanks a lot. dee.
  48. Geetesh kanade says…..I’m a 3rd year Electronics Engg. student. I had gone through your circuit of “Stress Meter” of 2005 magazine. I want to ask that can this circuit be implemented using micro controller? What sensors are required to measure stress and what are the different methods to measure stress?
  49. Khimm Pascua says …..Sir, we are graduating students, and our project is to produce useful product that related in electronics communications. we saw your post  and we are very interested on GSM sniffer – mobile phone detector.. we’re considering it as a good project. so, sir would you please do us a favor of mailing all the details needed in this project
  50. Pramod Thakur says… Sir I am studying software developing. That was a great post I liked it . I am not in a electronic field rather I am an in IT field but I love electronic and mechanical things very, and I try to make new things recently. I will definitely try my hand in solar charger.
  51. Nouman Nayyer says… Dear sir.Thanks alot for your very precious time. Sir it is working right now. Sir I m really thank full to u.Sir are u in india???
  52. Emmanuel Ihedioha from Deutschland says ….I am a student of Electrical Engineering. I am presently working on my Thesis and I have a problem at the moment. I am trying to design a circuit to power a recloser. The recloser requires a power of 100W and a voltage of between 48-60V DC. The major challenge for me is that I need to get my primary energy from the medium voltage line (15.5kV) and a transformer is not required in this design considering the size and weight. I need a compact power supply without a transformer and I find your article on ‘Transformer less power supply” very interesting. I need your advice on how to solve this problem using the X2 class capacitor of (15kV, 102pF) – Branden burgische Technische Universitaet Cottbus – Deutschland
  53. Ron Meador says….I read your blog article “Ultrasound and Insects” with great interest.You mention that Mosquitoes, Fleas, House Fly, Spiders, Cockroaches fall in the range of 38-44 kHz  for a response.If you were to guess about this…. where in that frequency range would you think that the Tarnished Plant Bug (Lygus lineolaris) be affected?
  54. Mishal Abe Varghese Says….I reach your site quite accidentally. Nice to meet you sir, because I heard of the name “D Mohan Kumar” from EFY . I’m a BTech electronics student at Mar Baselios Christian College of Engg: Peermade,Idukki and I’m an electronics hobbyist from my childhood. NowI’m interested in Micro controller programming.your blog is really helpful.
  55. Kaian Says….Hello i need some info on how the current flow because im using ur Circuit as my final year project can you give me more about it and it will be a great help thanks
  56. Amit Gupta says...Your article is very informative. Would really appreciate if you could help me with a few questions. Have been unable to find any information on this topic (except for your blog).Is it safe to use the liquid vaporizers such as All-Out which have 2.4% Prallethrin. Is it safe to use them in air conditioned rooms for long periods (8-10 hours) . What about usage for infants and/or pregnant women?Thanks in advance.
  57. Md. Ahsanul Haque Says …… I am a final year student and currently doing my final year project which is close to this article. This article was a great help to develop my project. My project is to develop a device that can produce enough electric power to charge small appliances like mobile phone etc. For initial research this article gave me a great assistance for my understanding and designing. So your advice will come to great help for me. Once again many thanks for opening a site like this.
  58. Shintoemmanuel Says ….. Sir, thank you a lot for ascribing a mini Wikipedia which inspires me a lot to my career.
  59. Othman Ahmed from Ethiopia Says……I would like to express our greetings and inform you that Ethiopian Electric Power Corporation announced on September 9th, 2010 the procurement notice for Invitation For Procurement of Electronic Energy Meter. We would like to express our greetings and to show our great interest to work on for the supply and construction of the above mentioned power transmission lines business with you. To begin with, we are happy to inform you that there is a large and continue project that may be a grate opportunity to you and for us can work together. It is Ethiopian Electric Power Corporation procurement project.
  60. Prashant Says….Very useful and informative post!!.Keep up the good work.
  61. Dinesh babu Says….highly informative , i never heard about this ideas.
  62. Austin says ….The information given in this blog is about inverter battery and very informative to me and excellent information is shared.
  63. Anil Goma says ….These are nice tips for proper maintenance
  64. Prerna Says… sir i m working on this topic as my mini project,,,, and i need the pcb layout fir the same can u please help me in its procedure
  65. Shiva kumar Says ….Dear sir Thanks so much for your valuable Article, that you have written in simple language that anybody can understand, with that help i have designed the Transformer less power supply and I learn a lot and I am Interesting in power Electronics so I am Expecting more more articles related to the same
  66. Aboobacker Says …Hi Mohankumar, Very useful for Basic Biology students.Cheer upand Continue ur efforts. All of the Best wishes.
  67. Anusha Ashokan Says ….Dear Sir,I m a PhD student working in the field of nanotoxicology . I was wondering if u can help me to get some good SEM images of blood cells. I have been trying for the past 2 weeks but im losing the morphology of cells ( RBC).
  68. Amit Gupta Says….Dear Dr. Kumar,Your article is very informative. Would really appreciate if you could help me with a few questions. Have been unable to find any information on this topic (except for your blog).
  69. Mishal Abe Varghese Says ….hello sir,I reach your site quite accidentally. Nice to meet you sir, because I heard of the name “D Mohan Kumar” from EFY . I’m a BTech electronics student at Mar Baselios Christian College of Engg: Peermade,Idukki and I’m an electronics hobbyist from my childhood. NowI’m interested in Micro controller programming. your blog is really helpful.
  70. Anargha Says …sir, can u explain the designing of the skin response circuit.,since we are doing this as our mini project.
  71. M.kanagasabapathi Says …Hello sir,Happy for i am introduce to you. i am electronics post graduate person and i am working as a project Engineer in a textile mill. I need your help for my project . Actually that project is a electric power management system. I want to measure the AC current from the CT. I use some method for convert the current to voltage. but it is not convenient for me. If you know any thing regarding to my query. please inform to me sir.
  72. Dinesh shandilya Says ..Please give me all electronics knowledge and projects and best topics for seminars.
  73. Jari Says …this helped me with my science homework
  74. Rohit says….Well done nice work.Its really nice to read such an enlightening article.
  75. Shibu.K Says …It is so interesting to know about the circuit.The scope for commercial manufacture may be sought out.Then it will be beneficial to the society.Boost up ur hobby.
  76. Phillip Mileski Says …Great blog, see you then. I should just give up and take lessons from you

11 thoughts on “Feed back

  1. If you please, I have a question. While I understand that the NiMH batteries have a “NOMINAL voltage” of 1.2 V….I also read in your article (and in other sources) that fully charged dry cells (e.g., AA ones) will read about 1.4 or 1.5…at least to start. I recently purchased a special Panasonic NiMH charger, which seemed like “a real winner.” Yet, I have found that the charger shuts off at about the 1.3 V level.
    What’s more, the insert with the charger listed 1.5 volts for both battery rating and charging voltage…and my multimeter shows that the charger is actualy operating at the 1.0 V level. I wonder if you could provide some clarification. I am mystified.

    As a matter of fact, I returned the unit (and a second one, as well!!), as it did not seem to be performing, and–at least for now–am using a conventional charger. Please what voltage should I be “looking at” for fully charged dry cells of this type?

    A gentleman–on a website–just criticized me…explaining that these should be charged about the same as NiCd cells (1.2 V)…and insisting that I was in error, but this issue seems to be more complicated than that…and the battery charger insert specs would seem to contradict the advice of the responder to my remarks. This is a real conondrum…and is kind’ve “driving me crazy!!” THANKS. ; )

    “Typical NiMH battery is rated 1.2 volts/cell. This is the nominal voltage of the cell that is discharging at the rate of C/10 at 25 degree centigrade to an end voltage of 1 volt. The battery pack has three 1.2 volt cells making a total 3.6 volts. When a fully charged battery is used, the discharge voltage starts from 1.5 volts followed by a sharp drop to 1.3 volts.” (Your words)

    “A fully charged cell supplies an average 1.25 V/cell during discharge, declining to about 1.0–1.1 V/cell (further discharge may cause permanent damage in the case of multi-cell packs, due to polarity reversal). Under a light load (0.5 ampere), the starting voltage of a freshly charged AA NiMH cell in good condition is about 1.4 volts.[20]” (Another source)


    1. Dr. TCH, Thanks for your query. All rechargeable batteries rated 1.2 or 1.5 volts requires more than 1 to 1.5 volts for proper charging.For example, 1.2 volts will charge properly only if we provide 2-2.5 volts. The Mobile battery is rated 3.6 volts, but the charger provides 5 volts.Even though the battery is 1.2 volts, it may show 1.5 volts in fully charged( New one only). But when we connect the load, this voltage suddenly drops to 1.3 volts and remains stable 1.2 volts for many hours. See this is applicable to only healthy battery. I think,the problem is in your charger. It should provide minimum 2 volts for single cell and 4-5 volts for 2 cell charging.

  2. hello sir,

    sir am doing m.tech, 1st sem n dey hav given oly a week time for mini project can yo suggest me some small scale projects…..????

  3. Dear Sir,
    Your article on LM3914 is very informative.I’d like to cascade 2 or 3 LM3914s to make a voltmeter with range of about 30volts & with LED1 indicating 1 volts.I wonder if you’d give me useful tips so I can make this voltmeter.I shall be very grateful.

    1. Dear Ashok,
      Thanks for the feedback . Your name seems to be familiar and I think you are contributing circuits in EFY. As you know, LM3914 has 10 current sinking outputs and only one input pin. So cascading is difficult and it is necessary to use 3 ICs separately using 3 inputs. For cascading purpose CD 4033 IC is used. You can make the 1-2000 volts meter using a single IC L 7107. Kindly see the circuit in the link https://dmohankumar.wordpress.com/2011/10/11/digital-panel-meter/#more-5305

  4. Respected Mohan sir,
    Thankyou for your informative notes. It gives great pleasure to see such impt topics described simply and up to the point. I would refer your website for my future studies.

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