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