Pages

Friday, 12 October 2012

Transformerless power supply

                Transformerless power supply,750 mA,12V(tested OK)

                                        We know many transformerless power supply circuits  which produce more than 100 mA by means of capacitance resistance and bridge construction. In fact, that circuits   may be  correct in theory,but if assemble practically,the current limiting resistors and zener get terribly heat and  damage  in short period. Even we use high watt resistors and zeners,things will be the same.Actually speaking, there is no need of current limiting resistor for high ampere transformerless circuits. After passing through  poly caps,We should allow the current to flow immediately as possible to the  opposite pole of AC.That is the safest way of handling  such circuits.The more we try to restrict current by resistor,or Zener, the more will be the heating.For eg,using 2.2uf cap  we obtain 150mA  max . Using zener, 3V ,Will produce less heat  than  a 12V, in same amperes.( same circuit.) If we increase the value of zener, to 9,12,15,16 so on, you can observe more heating of zener and current limiting resistors if any.

Here I have given  a circuit for 750 mA ,12 V DC  using 11uf capacitor.(2.2uf X 5 nos).

in this circuit, Triac will bypass current flow immediately to the opposite pole,by only supplying  the required volts  for bridge.if we reduce the value of 10k,more current flows through  triac and  bridge will get less volts accordingly. If phase of 230V is connected to parallel caps end,(top side in figure) will  reduce the chance of shock hazard ,since the other end of caps are  as same as neutral line and also all other points  do not have any shock potential. If  AC Neutral  point  is connected to  cap end,  all points will be as same as live....   So DO NOT TOUCH  any of the points even,phase and neutral are  connected in safest way. Triac or any other components  will not get more heat in this circuit. Loose contact to the AC mains connection may damage triac since immediate charge and discharge of 5 caps together due to loose contacts,produce high surge which cannot be widtstand by  triac . so connect  AC by means of proper  plugs only.Always be careful when work with mains.....
                                       Thanks & Regards
                                       Vineesh Kodambattil
Posted by at

8 comments:

  1. Unknown14 October 2012 at 23:19

    hello Sir,
    while checking the current shows 760 milli ampere but voltage i am getting is 13.8V also a humming sound i hear from somewhere in the circuit,but could not locate from where sound coming. can i increase the current to 1amp by adding more capacitors? i need your help for my diploma project for a remote controlled water level controller can you give your mail id? thanks for the post. can you add more circuits ?

    ReplyDelete
    Replies
    1. Sekhar javvadi25 March 2018 at 07:18

      i have a unique circuit for wireless water level controller
      send me your mail id i will send u circuit diagram

      Delete
  2. vineesh15 October 2012 at 03:50

    hello vasant,
    check for dry solder or loose contact for avoiding humming sound. you can increase current by adding additional caps .
    i will help you definitely if your doubts are from my known subjects. i will add more circuits soon
    thanks

    ReplyDelete
  3. Anonymous11 February 2013 at 17:40

    Actually what is the business purpose of this circuit ?

    ReplyDelete
  4. Unknown22 January 2014 at 08:44

    Dear Sir,
    I have built the circuit and confused on the watts of the circuit. In the above circuit 12v x 750ma = 9watts.
    On the 230v ac side the current drawn is also approximately 750ma. So will the total power consumed be 230v x 750ma or just the 12v x 750ma.

    ReplyDelete
  5. Unknown3 March 2015 at 22:38

    What kind of BT136 is used here?
    is BT136 600 just fine?

    ReplyDelete
    Replies
    1. lord aldebaran19 April 2018 at 06:05

      peak to peak of 230V is +/- 330V. voltage of triac are 400V to up!

      Delete
  6. Unknown11 November 2017 at 05:40

    Can I use only one cap.of 2MFD because I have required 12v. 100 ma current

    ReplyDelete

Subscribe to: Post Comments (Atom)