58 responses to “Online Support

  1. sir, now small led lamps working with 4v or 3.7v small battery (using mobile phone charges) are common. so pls. include an automatic circuit for this type of lamps.

  2. SIR – with reference to your circuit -Diac controlled LED flasher – I want to put a ONE WATT RED LED (may be 2 numbers in parallel) instead of the normal single 5mm LED – reason – its brightness is to low, I need to place the circuit at distance of about 80 to 90 meters.. Kindly advice the changes required in the circuit.
    Thanking you
    sachdevpm@gmail.com
    9323530011

  3. Hello sir,
    I am Kalai from Coimbatore. Can you tell me how can i hold charge in capacitor for some period.if there is any circuit, please send me.
    With regards,
    Kalaimani

  4. Sir i want.to detect faling object from top to bottom..i had use ir sensor bt the speed of the object is very fast.. Which sensor i should use..im using 89v51rd2 controller plzz help me

  5. Dear Sir:

    I have equation regarding the cell phone detector circuit. Which I would like to know the reason behind using 22PF C1,C2 capacitors. Would you please explain it to me.

  6. hello sir..im under graduate student..im working on project called SOLAR PRIORITIZER ..based on used to convert
    any common Inverter to Solar. unfrotunattly im not being able to find proper circuit and working operation for this project..i need circuit and working of the ckt for my final report for ur better understanding im giving you the main principle of my project so u can somehow help me regarding to this project ..plz
    WORKING PRINCIPLE:The mains ac input power of the inverter is taken through the Prioritizer. When sufficient solar power is available, the input power to the inverter is disconnected and the inverter is made to work in battery in the backup mode. At the same time the solar panel will be charging the battery. Thus the Loads will effectively work from the solar power. When the solar power reduces, the inverter is connected back to the ac mains making it work as normal Inverter.

  7. hello sir …pls help us with the stress meter project …i can’t simulate that using isis….can you pls provide ur contact informations so i can reach you directly…..

  8. sir…i am working on your stress meter project using LM3915…i tried to simulate the circuit in isis ..but it is showing errors like timestep too small…can you pls help me sir….?

  9. Dear sir,
    How can improve the mobile sniffer to recognise which phone is activated by finding the number. Have you any idea?

    Thanks in advance

    sebastian

  10. SIr, I want a simple circuit diagram for a 10 room hospital patient call bell for nurse with room indication and a reset option at the nurse station. All the rooms have call bell switch fitted and 10 wires drawn towards he the nurse station. Thank yoiu

  11. respected sir, i am a class 12th student and want to make a wireless telegraph machine using IR sensors and IR diode please tell e how to make the circuits which can both recieve and transmit IR signals as a message.
    to ,contact my email is shauryamittal3@gmail.com

  12. I noticed how you explained that a lower than design voltage (most appliances i believe are designed for 230 volts) actually consumes more electricity. I had two questions.

    1. Wont the power factor get reduced in case of lower voltage. Watts is calculated as IXVXPf. So for example lets say an appliance is designed to consume 460 watts at 230 Volt and PF of 1 (implying 2 amp current), so when the volt drops to 200 volt, the current jumps to 2.3 but the power factor is reduced to 0.8 so the total power consumed remains the same?

  13. Dear sir,
    My domestic electronic meter rating is 10-40A. it shows EL led blinks. when we remove all appliances and switch off everything, sometimes it glows and sometimes remain off. my bill is also very high every month. i have got all the electric points checked by the electrician. he says there is no leakage of current anywhere.
    now please suggest me, what should i do? whether change the meter or ?
    thanx
    waiting for your reply
    vinod, jammu

  14. sir,
    i am an final year electrical engineering student..i was planning on doing your project stress meter as mini project..but to be honest i don’t have much ideas about the touch pad used..i tried to find it and some one told that aluminium foils separated with two side tap is used..will it work??is the capacitance measured there??pls help us …

  15. I made the count down timer circuit provided by you but the problem occurs of timing precision.
    Switching was not done at calibrated time.

    I drive 1 watt LED as load through transistor, I want to turn off LED after 6 hours.

    But LED sometimes turn off after 5 hours , sometimes it turnoff after 5.15 hours, everytime reading is almost different.

    Please give me suggestion to obtain precise timing.

    Thankyou

  16. Ernie H again, regard the Light Dimmer circuit on this website
    ( ESK 77 ). Can some components be changed to make the dimming more noticeable ? The 50K or 100K pot are similar in performance. I’d like to dim it down to a dull glow for a night light, or max brightness for a torch.

  17. dear sir,
    I am interested in LED STRING driver circuit.
    I want to drive 60W inductive load using SCR Pcr406.
    Time interval of on time and off time will vary.

  18. Hello sir
    Can you suggest a circuit for charging a BL5C battery (3.7V 970-1050 mAh) with capacitor. It is for replacing a 4 LED rechargeable torch circuit. And how can I charge same battery with a nokia charger (5V 5.-00mA) I mean a current limiting circuit to charge the battery directly with a mobile charger. I mean a simple circuit

  19. Can someone help me remove huge distortion in my TDA 2006
    amp circuits —all three schematic circuits provided by the amp
    maker —-all distort loudly —how can I find a decent circuit
    using TDA 2006 —-Please help —months of awful distortion
    what components can I change/substitute /add to stop the
    buzzing growl ??
    appreciate — Carl

  20. Dear Mr Mohan,

    Great and good website, Congrats

    Can u help me in getting some insights in to induction and resistance heating and the difference between induction, Resistance and electric furnace heating.

    Thanks for your support

  21. SIR I HAVE DESIGNED THIS CIRCUIT FOR MY PROJECT AND THESE ARE THE MAIN QUESTIONS ASKED BY THE FACULTY TO ME –

    1) CAPACITOR IS THE CHARGE STORING DEVICE BUT HOW CAN IT HAVE ITS FIELD IF THIS CAN HAVE FIELD EVRY CAPACITOR CAN HAVE IT ?
    ( ACTUALLY THEY ARE CONSIDERING IT A NEW SORT OF IDEA )

    2) WHAT IS THE REQUIREMENT OF ANTENNA THEN IF CAPACITOR IS DETECTING ?

    3) CAPACITOR HAVING ITS FIELD AND ACTING LIKE AN ANTENNA THATS THE MAIN QUESTION BY THE FACULTY.

  22. SIR I HAVE IMPLEMENTED UR MOBILE BUG PROJECT BUT THERE ARE SOME POINTS I COULDN’T UNDERSTAND AND FACULTY MEMBERS HAVE ALSO POINTED
    OUT THESE ISSUES LIKE-

    1)The disk capacitor along with the leads acts as a small gigahertz loop antenna to collect the RF signals from the mobile phone

    BUT THEY SAY CAPACITOR IS AN CHARGE STORING DEVICE HOW CAN IT ACT LIKE AN GHz LOOP ANTENNA

    2)Capacitor C3 in conjunction with the lead inductance acts as a transmission line that intercepts the signals from the mobile phone. This capacitor creates a field, stores energy and transfers the stored energy in the form of minute current to the inputs of IC1.

    BUT THEY SAY HOW CAN A CAPACITOR CAN CREATE OR HAVE A FIELD IF THIS WOULD HAPPEN THEN EVERY CAPACITOR CAN HAVE ITS OWN SO CALLED ELECTROMAGNETIC FIELD

    PLZ SIR HELP ME OUT FROM THESE QUESTIONS I SHALL BE HIGHLY THANKFUL TO YOU

    EXPECTING A POSITIVE REPLY

    ATUL

  23. Greetings from Malaysia😀

    Sir, currently I am doing the mobile bug circuit. But unfortunately, the LED automatically turned on whenever I powered up the circuit (no active mobile activity around), but the buzzer didn’t sound either. Can you rectify what’s the cause of this error? FYI I assembled the circuit on breadboard and not PCB. Or is it necessary to use PCB instead of breadboard? Also, what’s the effect if the C3 lead length is shorter than the required 18mm?

    Thanks you, hope to get your speedy reply soon.

  24. Please sir,i am an undergraduate student.Pls can u help to redesign your mobile bug so it uses dual antennas from two ends of circuit based on your mobile bug operation and not the diode detection.Thanks

  25. hello sir,
    can u please provide us with circuit diagram of smoke detector using LM358 . we have surfed through all sources, we need your help sir,
    thanking u -Sadam

  26. Hello, I’m Professor of Physics at the city of Londrina in Brazil, I liked the design fordetector cell, I would mount the circuit in question, got help from an engineer to give me some tips, most do not get a solution for increasing range, you have the solution for a greater range between? about 10 meters for example? Agredeço muchattention, and congratulations for the project.

    • Hello Sir
      Thanks for your interest in my circuit Mobile Bug. It is designed as a pocket type detector for personal use with a range of 2-3 meters radius depending on the type of mobile phone.It can detect the cell phone activities close to us so that we can detect the misuse like snapping, sending videos,messages etc. Many people asked me to increase the range of detection. I have tried, but the circuit is showing false triggering, since the cell phone use far away from the circuit is triggering it and even the strong RF in the atmosphere is also making the circuit erratic.More over if the range is increased, it will not serve the purpose. We cannot detect, which cell phone is doing the misuse.You can slightly increase the range by changing the feed back resistor of IC1 with an 1M preset and a 470K resistor combination as feedback resistor . So that it is possible to adjust the gain of IC1.If you want to use in a Room, see my second circuit published in EFY. This is link https://dmohankumar.wordpress.com/most-used-circuits/

  27. Sir,
    I have been trying the Skin Response Meter published by you in EFY. Can you explain me the construction of a VU meter in the circuit given. I wasn’t able to get the reading correctly when i tried it with a voltmeter.

    • Dear jayakrishnan
      Try a transformerless design given in the blog. But the relay should get more than 100 mA current for holding the contacts. Usually relay driver uses DC from transformer.

  28. hello sir . D. Mohankar…….
    plz let me search an ELECTRONIC VIBRATION SENSOR ………it should have a sensitivity control (trim) and should just conduct when banged \ vibrated \ shaken \ oscillated
    OR can we make ourself using a piezo and opamp ? remember it should not generate any Ac signals which will disturb me required circuit …..SHOULD just conduct like a SWITCH
    THANK u VERY much in advance
    awaiting……………

  29. Dear Sir,
    I had made a small project which energize the relay according to the logic…
    But for powering this CMOS IC I want a transformer less power supply which can power this circuit and it can reliably run the relay…
    The requirement is :
    ———————————
    Voltage : 12volt
    Current : 100ma
    ———————————-

    The relay is resistance 200 ohms and 12 volt…

    So kindly help Sir ?

  30. Dear Sir,

    I have 2 extra Mobile batteries which is 3.7V which i want to use for my ringing bell and it requires 6V to operate. Currently my ringing bell is on adapter. which gives 6V but when no electricity that time it should operate from these batteries and also charger for these batteries. I need a circuit for this. pls. help me.

  31. i think i am making a mistake in the value of the capacitor used in transformerless power supply.
    225K as u say is 2.2 microfarad but acc. to my information and confirmed by various conversion charts on the net it is .22 microfarads. kindly enlighten me.
    naturally my circuit cld not give proper load current becaiuse of this mismatch.

    thanks in adv.

  32. don’t kow if you receive my last request but here it is again, I nee to know if I could get the 74LS47 chip and if so I need two of them, and how much it cost and when can i get it.

  33. Re: Fast Charger with Auto cut off.
    Dear Sir,
    What is the compoment at the base input
    of Tip 122 ? it say ZD 12v 1W but all I
    see is a resistor with no VALUE.
    Can you please be kind enough to give me some of your time let me know by email reply?
    Thanking you in advance.
    Great stuff you upload, keep up the good work…very helpfull indeed to learners.

    • The TV Guard circuit is connected through the cable to the TV socket. The cable has a center copper wire called Core and twisted thin wires around the core. This is the Shield which is the ground. You can connect the circuit as shown in the diagram. Simply cut the cable and insert the circuit between the cable and TV socket.

  34. Yes ,you can modify the Remote controlled Master switch as an IR beam cutter alarm. Following changes are required.
    1. Remove LED1, R2 and C3. 2. Replace T1 with BC 548. 3. Connect 10K resistor between the base of T1 and ground.
    When IR beam falls on TSOP 1738,its output turns low and T1 remains off. Pin 3 of IC1 gets low voltage level than pin 2 and its output remains low. When IR beam breaks,output of TSOP 1738 turns high and triggers T1 which in turn gives current to pin3 of IC1. Its output turns high and relay energize.

  35. Dear Sir,

    I’d like to use Remote Operating Master Switch in cooperation with an IR transmitter as an alarm system.
    What do I have to change in Remote Operating Master Switch schematic to make it act like an IR beam cutter?
    Is it possible?

    Thanx

    Kostas

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