Sunday, March 18, 2012

How to Make a Simple DC to DC Cell Phone Charger Circuit

It is estimated that there are probably more cell phones in India than the number of toilets present here. Astonishing, but true. A cell phone charger is one mate of cell phone that cannot be ignored because a cell phone would become dead without a charger.

Normally a cell phone charger come as an integral part of a cell phone package and we use it in conjunction with our AC mains supply.
But what happens if your cell phone gasps for power in the middle of a journey, probably when you are driving or biking away on a middle of a highway?
A very simple yet reasonably effective DC to DC cell phone charger circuit is discussed in this article, which can be easily built at home even by a layman.
Though the proposed charger circuit won't charge your cell phone at the rate equal to a normal AC to DC charger, nevertheless it will complete the function without fail and won't betray you for sure.
The circuit diagram can be understood with the following points:
We all know the general specs of a cell phone battery, it's around 3.7 volts and 800 mAH.
It means the cell phone would require at around 4.5 volts for initiating the charging process.
However a Li-Ion battery which is employed inside cell phones are pretty sensitive to bad voltages and may just blow off causing serious life and property issues.
Keeping this in mind the cell phone internal circuitry is specifically dimensioned very strictly.
The parameters just won't permit any voltage which may be even slightly out of the range of the battery specifications.
The use of the versatile IC 7805 in the circuit answers the above issue just perfectly, such that the charging voltage at its output becomes ideally suitable for charging the cell phone battery.
A high wattage resistor connected at the output of the IC makes sure that the current to the cell phone stays well within the specified range, though this might have not been a problem anyway, the cell phone would just refuse to charge if the resistor was not included.

Pictorial Diagram


You can use this cell phone charger for charging you cell phone during emergencies when there's no mains AC outlets, the circuit may be powered from any 12 volt lead acid battery or similar DC power source



Parts List

R1 = 5 Ohm, 2 Watt,
C1, C2 = 10uF/ 25V,
D1 = 1N4007,
IC1 = 7805, mounted on a heatsink,
Battery, any 12 volt automobile battery






218 comments:

  1. Dear sir. Please tell me
    that what alterations
    should i do, to charge two
    mobiles at a time from
    this circuit.
    Could i give the parallel connection with the existing mobile charging pin. As ic 7805 is capable of giving 1A out put. Please guide me

    ReplyDelete
    Replies
    1. Hi Rajagilse,

      Use the circuit given here:

      http://easy-electronic-circuits.blogspot.in/2012/03/deriving-high-current-from-7805-7812.html

      Delete
    2. dear sir, when light only 30 minet then how we charge my mobil wich type of make of a charger then my mobile arrgently charge please sir guide me

      Delete
  2. Dear sir, i read the article in your link. But the writer says about current more than 2A . In my case if i put two mobiles to charge, it may be less than 1A. Therefore i think , what happens if i put another 5 ohm resistor and 10uf capacitor in parallel to the existing output of ic 7805

    ReplyDelete
    Replies
    1. Hi Raja,

      2Amp is the max current rating, that doesn't mean that the cell phone will draw the whole current, it will use only the required amount.

      You will need to increase the wattage of the resistor, not the value, one capacitor is enough at the output.

      Delete
  3. Dear sir , an electrician told me that "In about 80% of the cases the reason for decreased battery performance is a sulphate buildup on the plates . And pulse or equalization charging can stop Sulphation . What does its mean ?do you have any circuit about it ? and please also give me an idea that what will the effect of "daily use and charge process " on inverter battery .
    Thanks
    Pankaj Pandey

    ReplyDelete
    Replies
    1. Hi Pankaj,

      That's quite true, use of PWM controlled battery charging is recommended for tackling this problem with lead acid batteries.

      I will surely publish one article soon, discussing this issue elaborately.

      Thanks

      Delete
  4. Dear sir, Can I give the Input of 12v 50 amps to it. Its an inverter battery.. Will the circuit work fine or it burns out... Also tell me What is the maximum current and voltage that 7805 can hold..
    ~~~~~~THANK YOU SIR~~~~~~~~~

    ReplyDelete
    Replies
    1. No problem, you can it use the battery,
      Maximum 24v input, max 1amp output

      Delete
  5. why we should not connect cell phone directly to the battery

    ReplyDelete
    Replies
    1. The cell phone will not accept any voltage that's above 5V, the battery may be above this limit, therefore the above circuit is required.

      Delete
    2. Mr. Swagatam-

      If the voltage was less than 5V, for example a small, single cell, hobby grade LiFePo4 battery, which puts out less than 4V... could I just hook the battery directly to the cell phone as a small "emergency" charger?

      Thanks for any information and have a great week.

      Sincerely,
      Jim Kennedy

      Delete
    3. If it's 4V then it would charge your cell phone when hooked directly, anything less than 4V would make the charging inefficient and sluggish.

      You are welcome!

      Delete
  6. sir why u dont have D1 = 1N4007, in Pictorial Diagram

    ReplyDelete
    Replies
    1. It should have been there, diagram fault.

      Delete
  7. sir,can I use a dc motor to provide 9v ?

    ReplyDelete
    Replies
    1. Yes....but you may have to spin it very hard to make that much volts..

      Delete
  8. where shall we connect the diode which isnt shown in th figure?

    ReplyDelete
    Replies
    1. At the input of 7805, see the bottom figure.

      Delete
  9. dose the capacitors terminals matter here??
    if it matters can u tell me which terminal is to be connected to the ic

    ReplyDelete
    Replies
    1. if it's non polar then it won't matter, if it's polar then positive will go to the shown IC pins

      Delete
  10. can i use a 6volt 4.5 amp battery for making this circuit instead of 12volt battery
    ???

    ReplyDelete
    Replies
    1. is there no difference on output either to uses 12v or 6v 4.5AH bettery?
      what changes are required to use 6v 4.5AH bettery
      waiting for ur reply

      Delete
    2. No changes would be required, use the same circuit for 6V input.

      Delete
  11. and wat about the diode terminals??
    dose this matter too?

    ReplyDelete
    Replies
    1. Yes diodes have polarity, the banded side will go to the IC pin.

      Delete
  12. sir i used the above components
    but i failed?
    plz help me?
    hw sal i test whether my circuit s correct or not!

    ReplyDelete
    Replies
    1. Dis to test with a cell phone, the output pin must be connected to the IC with correct polarity.

      Delete
    2. Ravinder Kumar Here
      Dear sir can you please tell me the circuit component value for 6 VOLT ,i have planned to prepare mobile charging circuit run with 6 volt lead acid battery ....

      R1 = ?
      C1, C2 = ?
      D1 = ?
      IC1 = ?
      Battery = 6volt lead acid .
      waiting for your reply..

      Delete
    3. you can use the same circuit which is shown above.

      Delete
    4. Ravinder Kumar from Indigenous Home made Tech is here -Dear sir i used u r given circuit (with C1,C2= 10uF/25V )BUT by using diode and resistance does not work ,so i have removed diode and resistance now its charge but not 100% it charges the cell phone only to 70% by using 6volt 4.5Ah Battery ,
      Request you please suggest to increase charging efficiency limit to 100% .

      Delete
    5. I am sorry the above circuit cannot be upgraded any further. You can use an LM338 design and adjust the voltage to suit the cell phone needs. You may refer to the first circuit in this link:

      http://homemadecircuitsandschematics.blogspot.in/2012/04/ic-lm338-application-circuits-explained.html

      Delete
  13. can i connect the output terminals to a socket and then connect it to a battery charger??

    and is there any other way by which i can test the circuit before connecting it to cell phone chager??

    sir sir is there any specification for the wire that is to be used to connect the 6v battery to my circuit??

    ReplyDelete
    Replies
    1. This circuit has been tested by me, and it works.

      Just connect the output of the circuit to a suitable pin so that you can insert the pin into the cellphone charging input.

      You can use any type of wire, as long as it conducts electricity it'll be fine.

      Delete
  14. muje aik aisa cicuit chaye jes me input 12-24 volt 50amp ho likin out put 12volt 800map ho

    ReplyDelete
    Replies
    1. Refer the first circuit in the following link:

      http://homemadecircuitsandschematics.blogspot.in/2011/12/how-to-build-simplest-variable-power.html

      Delete
  15. sir i m getting an output of 4.3 amp by using a 6 volt battery??
    wil that do ??
    or i sal go 4r a 12 volt battery?

    ReplyDelete
    Replies
    1. you mean 4.3 volts right?

      Yes you may use a 6v battery then.

      Delete
    2. no sir
      i was saying about the output current .it iwas 4.3 amp

      my output voltage is around 3.2 volts
      by using a 6 volt battery

      Delete
    3. No there's something wrong with your circuit, the output voltage should be 5V even with 6V input.

      The current is not important here as long it is able to provide above 500mA, the cell phone will get charged.

      Delete
    4. okk sir i will recheck my circuit

      Delete
  16. why can we continue to connect about x6 of the same lithium ion cell(i mean the collapsed one) in parrallel and in series to get a good output then your circuit sir

    ReplyDelete
  17. Swagatam,
    All your circuits are simple and clear, it's great!

    Your circuit uses R1 = 5 Ohm, 2 Watt, and C1, C2 = 10uF/ 25V, does it need to be exactly 5 Ohm, 2 Watt, and 10uF/ 25V or we can also use other values suppose if it is not available ?

    ReplyDelete
    Replies
    1. Hi Cedar,

      Nothing is critical here except the IC number.

      You can use any value for the resistor from 5 to 20 Ohms, however increasing the value will slow-up the charging process.

      You can use any value above 1uF for the caps too....

      Delete
  18. sir what if i only use 78m05 and a 5 ohm resistor,,, what will happen? sorry for the bad english..

    ReplyDelete
  19. tnx sir it works fine,,sir can i know what is the difference in using all parts that u give and using only 78m05 and a 5 ohm resistor (2 parts),, again sir thank you so much,, you re our macgyver of today,,

    ReplyDelete
    Replies
    1. Yes you can use only the two parts it will still work. However the diode is important because it protects against wrong input polarity connections.

      Delete
    2. thank you so much for the info.. god bless you always,,,
      sir can i ask you again,, how to adjust ( increase ) ampere of a battery? iam 24 y/old i have a son 4y/o i gave him a battery operated toy car,, 6volts 4.5 ampere.. he can only play it for only 1 hour,, can i adjust its ampere so he can play it longer?.hope that im not bothering you...thank you so much...

      Delete
    3. Hi Kataga,

      If you reduce the ampere of the battery the car will not work properly, you can add one more 6V/4ah battery in parallel to the existing one for increasing its operating time.

      Delete
  20. thank you so much,,, sir.. i dont know how to thank you for all your hel.. god bless you,,and your family.. keep sharing your knowledge...

    ReplyDelete
    Replies
    1. My pleasure kataga, God bless you too!

      Delete
  21. i,m using a dc-dc mobile charger
    i/p-7-12 V
    protection circuit required or not
    charger should be removed after how much time ..

    ReplyDelete
    Replies
    1. All cell phones have in-built protection circuit, so it's not required externally.

      Delete
  22. if I put 5 Ohm to circuit. So how many is ampe curent output ?

    ReplyDelete
  23. sir i have question f you dont mind. can i put led light? and wer should i put?

    ReplyDelete
    Replies
    1. Put it across the output 1uF capacitor with a 1K series resistor....

      Delete
  24. sir... i have 3old calc in that i get 1.9v solar panel(each)its possible to make solar cellphone charger??????.. its possible pls send diagram. my mail id dass143@gmail.com thks

    ReplyDelete
  25. I have an android mobile and i want to know about the terminals of the charger which i put into my mobile

    ReplyDelete
    Replies
    1. Normally the pin which is shown in the diagram has its outer metal connected to the negative and inner metal to the positive of the voltage source.

      Delete
  26. Thnxx
    I know that but in android chargers its a bit different its a flat pin charger and i tried checking with a multimeter
    Thnx in advance

    ReplyDelete
    Replies
    1. You will need to find out the positive and the negative outputs of the socket and connect them to the above charger appropriately, you may take the help of a phone technician.

      Delete
  27. Sir, I want to make solar mobile charger. please send me details along with circuit diagram. my emai id is saisuvajit9999@gmail.com

    ReplyDelete
    Replies
    1. You can use the circuit shown in the above article, connect the input to a suitable solar panel, it will start charging the cell phone.

      Delete
  28. hi sir. Can i connect 12volt solar cell? If yes what should be the current rating of the solar cell . My battery is 3.7 volt @1020mah

    ReplyDelete
    Replies
    1. You cannot connect the Li-Ion cell directly to this circuit, the above circuit is for charging cell phones, not the battery directly.

      You may connect a 15V, solar panel at the input, current can be anything that's above 1amp.

      Charge the battery by putting it inside a cell phone.

      Delete
  29. sir, my cell phone requires 4.8v/1300mA ........would it be safe to supply of 1.5 amp from 7805 ?

    ReplyDelete
    Replies
    1. the 5 ohm resistor will take care of the current, so it's safe according to me...

      Delete
  30. Sir can you give me diagram by which through this circuit i can charge two mobile cell..

    ReplyDelete
    Replies
    1. you can refer to this article:

      http://homemadecircuitsandschematics.blogspot.in/2012/05/dc-to-dc-double-cell-phone-charger.html

      Delete
  31. Hi

    Just want to know whether the AC-3N Nokia Charger with 5V 350mA can be used on a device that requires AC 6V 300mA ?

    Thanks in Advance.

    Regards

    ReplyDelete
    Replies
    1. Hi,

      Yes it can be used if the unit is not specified with critical operating parameters.

      Delete
  32. hi. sir.. ye ckt mere meri herohonda HUNK bike me lagani hai.. to kya lagegi.? isse mere nokia 5230, apple 4s charge hoga.?? agar bike running hai to koi problem to nahi hogina..?? ya bike off kar k cells charge karne padenge.??? plz.. help me.. ans me..

    ReplyDelete
    Replies
    1. Hi Abbas,

      you can connect its input to the battery, you can charge your phones even while riding.

      I am not sure whether it would charge all your phone, you will have to check it out.

      Delete
  33. Greetings!!

    Sir it is safe if i put the unit somewhere safe under the saddle and permanently attach inputs to the battery?.

    How about inline fuse, it is safe without it Sir? Thank you!

    ReplyDelete
    Replies
    1. Greetings!

      According to me it's a very safe circuit, a fuse is not required. Permanent connection to battery is OK. A heatsink is essential for the 7808 IC

      Delete
    2. Thank you very much Sir, some other query... what size of heatsink it should be? can you explain it by inches Sir, what i've got is just 1inch square with a half inch thick from the rib.

      Another thing Sir, your diagram says 1uf/25v cap while partlist is 10uf/25v cap. what is the difference using either value Sir. Thanks


      Jane

      Delete
    3. Hello Jane

      Instead of using aluminum piece, it would be better to use a ready-made heatsink, as shown here:

      http://www.futurlec.com/Pictures/TO220LGBA.jpg

      Capacitor values are not critical, you may use any value.

      Delete
  34. Hi Sir,
    I want my motorcycle to have two set of horn tone, one lower or just the stock horn tone and the other is louder or even loudest if possible, without sacrificing the battery charge.

    Do you have a circuit for this Sir? or any other suggestion to obtain a more louder horn but maintaining the stock horn, maybe using a toggle switch for the purpose of having a dual horn tone.

    Thank you very much Sir, I hope i could do it with your assistance Sir.

    Regards,
    Jane

    ReplyDelete
    Replies
    1. Hi Jane,

      I'll try to get a suitable circuit soon....

      Delete
  35. sir i want to make batry charger for li-ion battry (3.7v,1300mAH),please tell me the simplest circuit plzz...

    ReplyDelete
    Replies
    1. you can use the above circuit, but you will have to monitor the charge manually, the moment it reaches 3.7V you will need to switch off the charger.

      Delete
  36. Hi Sir
    I am trying to charge my cellphone (Nokia) with lead acid 4.5 volts small battery ( which comes fitted in the emergency LED lights). For this purpose I connected the said battery directly to the phone but it did not respond. I you have any circuit diagram for this purpose, please send on the following address. My phone need 4.9 volts to 5.3 volts and 500 MA for charging.
    Thanks,
    My address: adnan_nagra@yahoo.com

    ReplyDelete
    Replies
    1. Hi Adnan,

      if your cell phone uses a 3.7V li-ion cell it should accept charge from a 4.5V battery.

      try putting a 5 Ohm 1 watt resistor in series with the battery positive,it might start charging.

      Delete
  37. Hi Sir, is it possible to charge a mobile phone using another mobile phone's battery as input source via this circuit?

    ReplyDelete
    Replies
    1. Hi Sanket, no it's not possible because the source voltage must be at least 0.6 volts higher than the battery voltage which is being charged, here both will have identical levels, so not feasible.

      Delete
  38. I want to convert 6v 4.5amp to 5 volt 1amp.so plz can u suggets me the circuit if it possible plz do it fast?

    ReplyDelete
  39. how to convert 6 volt 4.5amp to 5 volt 1 amp

    ReplyDelete
  40. Sir, I have 9 volt dc battery.. i wants to make a DC to DC charger for this 9 volt battery.. i wants to make a charger in such a way that it will get charge while in use.. like batteries in Mobile phone so on.. Please tell me how to make one

    ReplyDelete
    Replies
    1. What is the AH rating of the 9V battery, because an ordinary PP3 will not charge a cell phone battery.

      Delete
    2. hi sir,, actually i am visualizer.. i do not have any knowledge about electronics or electricity.. I just see things, read things, tries to understand and creates the possibilities not practically but in my thoughts.. so please help me..

      Can we make a charger(Circuit) for any rechargeable DC battery... which can charge himself??? like take 9volt dc rechargeable battery..

      Please do let me know on atulkamble99@gmail.com

      Delete
    3. Hi atul,

      Thanks for the nice question, but no that's not feasible in the present world.

      Delete
    4. Sir,

      i am trying to visualize something plz help me to get it possible.
      i will ask you some questions.. plz try to figure it out whether it is possible or not

      (if have 1.2 volt with 2400mA dc battery)
      upto what voltage you can amplify? current should be minimum 500mA.

      sir there will be a lot more questions i will be asking you... plz try to contact through mails. atulkamble99@gmail.com.. this will be lot more easy..

      Delete
    5. You may try experimenting with this circuit for getting the desired results:

      http://homemadecircuitsandschematics.blogspot.in/2012/10/1-watt-led-driver-using-joule-thief.html

      Delete
    6. thank you sir...

      regards,
      Atul

      Delete
  41. what if when i use 7808 Ct in this...

    ReplyDelete
  42. dear sir,
    can i use alkaline battery of 1.5V instead of lead battery.(pencil cell)
    and using total 4 cells will make it to 6V.
    and if it is so then please inform me is there any other change in circuit due to it

    ReplyDelete
    Replies
    1. http://homemadecircuitsandschematics.blogspot.in/2012/11/homemade-cell-phone-emergency-charger.html

      Delete
  43. Hi Sir...Excursme...How You Solve Problem With Your Cree XML-T6 driver ?
    ThankYou

    ReplyDelete
    Replies
    1. Hi Guruh,
      I'll post a related article soon in my blog....

      Delete
  44. please, i sent you before if i can use only resistor to make simpler version of this charger.
    i'm supervising a group of kids in science clup and they want to make mobile charger.. and i want to be as simple as possible
    waiting for your respond

    ReplyDelete
    Replies
    1. you may use a resistor only when the source voltage is 5V or less, if it's more than 5V then first it will need to be dropped to 5V and only then a resistor may be used as shown in the above article.

      Delete
    2. yes it would work in mobiles which use cells having 800 to 1000mAh rating.

      Delete
  45. Sir, What Type of Capacitor I use Ceramic/ Eletrolitic

    ReplyDelete
  46. hi swagatam sir,
    i work with this circuit but it slowly charging i want improve the chargering levels (means fast charging) tel suggetions sir and hw can i measure current flowing through this ckt sir. i think small currents are flowing. and how can i improve the current in this circuit sir.
    plz rly me sir.

    ReplyDelete
    Replies
    1. Hi Seetha,

      The current can be increased by appropriately decreasing the value of the output resistor. try smaller resistor values for charging the cell phone faster.

      Delete
  47. using above circuit only some phones charged my ph nt chh arging ph specifications r 3.7v 880ma bt above circuit gives 890ma if load will connect to the circuit current drops na sir

    ReplyDelete
  48. i changed 5 ohm resistor and place 1 ohm and checked bt charging levels are nt inceased. nokia phones r charging properly sir i maen those specifications r 350ma. from the circuit i am connect one usb for samsung and apple phones and also connect nokia charger teminals for charging bt samsung phones charging slowly sir those phs require 880ma. how can i solve this problem rly me.

    ReplyDelete
    Replies
    1. you can try the following design:

      http://homemadecircuitsandschematics.blogspot.in/2012/05/dc-to-dc-double-cell-phone-charger.html

      Delete
  49. thanx sir

    using normal charger teminals charging is possible bt connect usb for apple phones charging is nt possible sir

    ReplyDelete
    Replies
    1. check the USB connection polarity, it might be incorrectly wired.

      Delete
  50. Will it work with 6 volt emergency light battery

    ReplyDelete
  51. Dear sir. Please tell me
    i have 10uF/ 63V,
    its ok

    ReplyDelete
  52. dear sir i used resistance 5.6 ohm instead of 5 ohm..is there any effect of this

    ReplyDelete
    Replies
    1. sir in the first diagram,in which there is input of 12 dc battery,will there also need diode ??
      or if i want charge from automobile then i se diode??
      thankss

      Delete
    2. diode is placed only for safeguarding the circuit from accidental reverse input connection. You can remove it but be sure you connect the input polarity correctly then.

      Delete
  53. thanks sir
    sir can you tell me how much time required for charging a mobile???
    & sir i have project about bicycle dynamo. sir if you don't mind can you send me an easy diagram to make bicycle dynamo/bicycle generator??

    ReplyDelete
    Replies
    1. 2 to 3 hours will be required.

      you can connect the dynamo output to the above circuit via a bridge rectifier stage and start charging the cell phone as explained above.

      Delete
  54. it help me alot.THANKS SIR...
    sir app bta skte ha k ak battery ktne dair run kr skti haa??

    ReplyDelete
    Replies
    1. i mentioned it in the previous comment, 2 to 3 hours.

      Delete
  55. sir can i connect this circuit with motorbike battery and car battery??
    if yes ,so will there any problem of input & outout current because automobile battery's current is very high??
    i know voltage is not a problem.. what about current.
    THANKS FOR YOUR ALL PREVIOUS HELP SIR.....

    ReplyDelete
    Replies
    1. As long as the input voltage is within 24V, current will not mater, so you can use it freely with your motorcycle battery also.

      Delete
  56. sir please tell me if you have any knowledge about any softwere about circuit designing in which bicycle dynamo ,d.c motor or other mechanical equipments present????

    ReplyDelete
    Replies
    1. No, sorry I don't have any such software.

      Delete
  57. assalam o alaikum i am omar respected sir i want charge my cellphone and also a battery that is connected to this circuit... also my cellphone battery have 1300 ma current requirment. . . suggest me the possible design. . .
    thanks

    ReplyDelete
    Replies
    1. Hello Omar, just replace the 7805 with a LM123 and it will become suitable for the required application.

      Delete
    2. sir,this condition ok...the 12v continuously going at 7805 and step down to 3v...normally example you take mobile charger,u have charging mobile, charging and the battery is full....and automatically disconnect the charger....

      in this project,only charging the battery not getting the charge is full condition automatically disconnect condition..how to get automatically disconnect after the batter full..plz give me the circuit and information.........

      Delete
    3. mobile chargers do not have auto shut off feature, rather cell phones have auto cut off feature in-built, therefore it's safe because the cell phone in-built circuit would cut off as soon as its battery gets fully charged.

      Delete
  58. Dear Sir ,

    I would to know , can I use this circuit to power up mobile phone without battery attached.

    Thanks in advance.

    ReplyDelete
    Replies
    1. Nope! the circuit will require an input source, otherwise it won't work

      Delete
  59. Dear Sir ,
    Can i use your diagram to power up my cell phone without attached the battery to the phone?

    Thanks

    ReplyDelete
  60. can i use 4.7 ohms 2 watt resistor instead of 5 ohms 2 watt resistor

    ReplyDelete
  61. can i use mobile charger to start motor?
    motor = 0/6.0 v
    charger = output - DC 6.0 v

    ReplyDelete
  62. can i use mobile charger to start motor?
    motor = 0/6.0 v
    charger = output - DC 6.0 v

    ReplyDelete
  63. HELLO SIR..
    SIR MJHE UNI PROJECT K LIA AK CIRCUIT CHAHEA JISME 2 IC lm714 US HO..SIR PLEASE KOE HOMEMADE PJOJECT KA LINK SEND KR DIJEA..
    I WILL BE THANKFUL TO YOUU................

    ReplyDelete
    Replies
    1. Hello Abdul,

      You can try the first circuit given in this link:

      http://homemadecircuitsandschematics.blogspot.in/2011/12/how-to-build-electronic-spy-bug-circuit.html

      Delete
    2. ....sorry, the above circuit uses a single 741, try the following one, replace the LM324 opamps with two IC741:

      http://homemadecircuitsandschematics.blogspot.in/2012/04/make-this-simple-motion-detectorsensor.html

      Delete
    3. thanks sir.
      but I m student of 3rd semester. this schemetic is little bit complex
      for me.so sir please send me an easy schematic. so I can make it .
      thank u sir for helping me a lot... ...

      Delete
    4. Hi Abdul,

      I don't have any simpler circuit than this at the moment, I'll try to find it and tell you soon.

      Delete
    5. HELLO SIR........
      SIR APNE JO SEND KIA THA LINK ME WOHE BNA RHA HUU..
      MENE APKE BLOGES ME RELAY CONNECTION PARHA . KCH SMJH AYA SIRF YH BTA DE AP K JO RELAY KI 5 PINS HA WO KHA KHA CONNECT HA???
      N/C & N/O KHA CONNECTED HA:COIL TERMNALS KHA CONNECTED HA??
      AUR JO PICTURE ME 12 VOLT K UPAR BLUE LINE HA WO KHA CONNECT HORAE HA.
      SIR I HAVE ONLY 3 DAYS TO MAKE IT .
      THANKSS.....

      Delete
    6. The square box named 'relay" is the coil of the relay, among the contacts the upper circle is the N/C and the lower circle is the N/O, the central link is the moving pole of the relay.

      Delete
    7. THANKS SIR.. YOU CLEARED MY CONCEPTS.
      BS MJHE YH BTADE N N/O, N/C & MOVING POLE OF THE RELEY CIRCUIT ME KHA CONNECTED HAIN????AK TO YH RELAY ME CONNECTED HA LEKIN YH CIRCUIT ME KHA CONNECTED HA YH NAE PTA CHAL RAHA..

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    8. N/O, N/C and the pole are not connected to the circuit, they are connected to the load or an alarm via AC mains, there's no connection with the circuit.

      If you are using a DC alarm then you may connect it with the circuit 12v supply.

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    9. ok sirr
      sir jo 12 volt dc alarm ha iska koe link send krde. mjhe zehan me idea nae arha..
      project bhht acha lga ha mjhe iSlia yhe bnana cha hu.complex ha but i will try my level best.
      aur relay ki 3 wire jo alarm se connect HA uska be lnk btade
      THANKS SIR.......

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    10. sir mjhe dc alarm ka idea nae ho rha. plz send me link about dc alarm. aur is circuit me sensor knsi chez ha jaha se motion indicat hogi aur alarm on hoga

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    11. don't make the aarm, buy it from the market, you can use a car musical horn or a 12v musical door bell.

      relay connection:

      pole to 12V(+), N/O to alarm (+) wire and (-) of alarm to circuit ground or supply negative.

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    12. THANKS SIR..
      sir yh jo diagram me A1 HA ISKI Pin 1 to led k sth aur pin aur pin 2 potentiometer k sth ha but confusing pont is k pin 1 & pin 2 k bech me se ak point upar 12 volt aur resister k sth node bna rha ha. yh ks pin se nkal k upar ja rha ha.aur sirf A1 KI 3 PIN CONNECTED ha bki kia ground krni ha???
      and same question for A2 .usme be pin 5 & 7 connected ha aur bech mese ak wire jake grounded ha.yh knsi wire ha???

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    13. SIR IS THERE ANY WAY TO CONNECT WITH YOU & YOUR KNOWLEDGE DIRECTLY????
      BECAUSE SOMETIMES I WANT QUICK ANSWERS AND FROM BLOGS, I HAVE TO WAIT 1 DAY. KINDLY TELL ME ANOTHER WAY SO THAT I CONNECT WITH YOU DIRECTLY ..
      THAKNS SIR..

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    14. It's the supply pins of IC324....positive line goes to pin4 and the ground pin goes to pin11.

      I am sorry you can contact only through this blog.

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    15. SIR.........
      http://datasheetoo.com/datasheet-application/automotive/electronic-siren-circuit-diagram-using-741-op-amp-ic.html
      THIS IS ELECTRONIC SIREN . SIR I WANT TO ASK THAT SPEAKER IS PRESENT THERE,WHERE I CONNECTED INPUT SOUND SO SPEAKER CAN AMPLIFY???
      THANKSS SIR FOR HELPING ME A LOT...

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    16. I did not understand your question, what are you trying to make?

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    17. Sir please tell me connection of relay with dc alarm . I am using dc alarm for output.
      Secondly, if I want to check the circuit that it is working or not without an alarm, how I check it???
      Actually mjhe teacher ko check krwana ha without alarm.

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    18. relay connection:

      pole to 12V(+), N/O to alarm (+) wire and (-) of alarm to circuit ground or supply negative.

      The red leds will be shut off after setting up, and when a motion is detected across any of the LDRs the relevant red LED will light up indicating a motion.

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    19. This means sir that N/0 does not use in this circuit.??
      And pole se phir 12 volt p connect krna ha?? I can't understand. Please send any diagram from which I understand.
      THANKS....

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    20. pls read the connections again, N/O is connected to (+) of alarm circuit, N/C is blank, not connected anywhere.

      (-) of alarm circuit is connected to supply negative

      relay pole is connected to supply positive

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    21. I UNDERSTAN SIR..
      SIR IN MY CIRCUIT,ONLY ONE LDR IS WORKING ,WHEN I DISCONNECT ONE LDR,OTHER LDR WORK AND OTHER PROBLEN IS THAT IT WORKS IN OPPOSITE FORM MEANS WHEN IT DETECTS ANY MOTION,LED OFF OTHERWISW IT ON ALL THE TIME.
      AND SIR TELL ME HOW I SET P1 & P2???
      THANKSS....

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    22. you may have connected the pinouts wrongly, i have tested this circuit it works superbly.
      when correctly set both LEDs will switch off completely and illuminate only when a shadow is detected across any of the LDRs.
      I have explained the set up procedures in the article.

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    23. sir kindly tell me the connection of potentiometer?? like it's first leg is connected to 10k resister ,i m confused about second & third pin connection.tell me the connections for both , P1 AND P2.
      THANKS FOR HELPING ME ALOT..

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    24. use the center pin and any one of the other pins, that's all...
      center pin is compulsory, the other one can be any of the remaining two.

      I have made some changes in the diagram, please do it in your circuit also, it will give better results, and pls comment on motion sensor article, not on this page.

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  64. How Many times We can charge our phone by using 12V battey ????

    ReplyDelete
    Replies
    1. will depend on the AH rating of the battery and the phone.

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  65. hello sir!!!!
    can u please tell me what is the function of capacitors in the above circuit ???

    ReplyDelete
    Replies
    1. Hello Danish,

      It's there for filtering noise and voltage spikes.

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  66. Hi Swagatam,
    I came here just to say Thanks. I've been following your blog for some time and I quite like it. People ask all sorts of questions, some silly though, but you responded nicely every time. Keep it up. I'll keep reading every publication of yours and may be I too will seek help sometime... Pukhrambam

    ReplyDelete
  67. hello sir
    sir mujhy 12v bike ki battery sy mujhy 15v out chahey or internet device chalane hai
    or woh bhe atomatic yane k lite jae to auto battery per ajae plz plz plz plz plz sir help me............plz plzp plz.

    ReplyDelete
    Replies
    1. hello faizan,

      make this circuit first for 12v to 15v conversion:

      http://homemadecircuitsandschematics.blogspot.in/2012/09/led-emergency-light-circuit-using-boost.html

      then i'll tell you what to do next.

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  68. Heloo Dear sir
    I like your response and advise and bless you!!
    My question is is it good to use 5v,1w solar panel for the above circuit application with out 7805??What about 6v ,1w solar panel with 7805????

    ReplyDelete
    Replies
    1. Hello Alealu

      Thanks!

      with a 5V solar panel you don't have to use any IC at the output, you can connect your cell phone directly with the panel via a 5 OHM/ 1 watt resistor....it will start charging.

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  69. Thank you,and what about the fluctuation of the sun,it cant affect the battery?
    bic the output from the sun is not constant,

    ReplyDelete
    Replies
    1. when you say it's a 5V panel it signifies the peak value at peak sunshine, so technically it cannot exceed this level.

      But anyway you can use the above circuit in conjunction with it for better safety.

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    2. I mean, even if it is 5v peak this voltage do not exceed 5v but may goth below 5V ,so the voltage may be 5,4,3,2.....v depending up on sunshine,As a resale,is such low voltage is safe for mobile battery life????

      Thank you

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    3. The cell phone will stop charging once the voltage reaches below 4V.

      Lower voltages will not harm the cell phone.

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  70. sir meray pas12v 2.5amp dc bttry hy or mujay 9v aor 1amp output ke zarurat hay,,,,plz Circuit Diagram share krday,,,,,

    ReplyDelete
    Replies
    1. You can use a 7809 IC at the output, it will give you a 9V/1amp output from your 12V battery.

      The connections will be same as in the above 7805 design

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  71. good day sir... i did loved your blog.. bcoz its very usefull here in our place this time becauze we have no electricity... so i did make your circuit but i got an error in my cellphone.., bad contact of charger... i did use 2 10uf, and 5ohms 2 watt.. pls help.. thnx..

    ReplyDelete
    Replies
    1. thanks charles, try 10 ohms in place of 5 ohms or some higher value and check the result

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    2. tnx sir... i'll try as soon as i can buy 10 ohms or higher...
      -----
      sir, i have here a 9v dc solar panel.. i only get around 5.5v-8v dc (not stable) if its not so sunny... can i still use this circuit?

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    3. yes, you can safely use the above circuit with your solar panel.

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  72. Hello sir.
    Sir I want some help from your side. Sir I have project regarding computers logic design. Topic is:
    DESIGN AND IMPLEMENT A CIRCUIT THAT COULD GLOW A LED WHEN 3 OF THE AVAILABLE 7 TANKS NEED A REFILL.
    Sir I want circuits or if u have idea, so tell me.
    THANKS SIR.........

    ReplyDelete
    Replies
    1. Hello Abdul,

      You will have to provide me with full details regarding the application need, only then I would be able to come up with something suitable

      Delete

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Readers are advised to proceed with the construction of the presented circuits only after understanding the concepts from the core. Not adhering to this can lead to failures and frustrations.