nuyi said:
without using step down transfomer can anyone teach me to details on how i can get 12vDC from 220vAC like such i use to see in modern day charger or power supply pls eager to know this . thanks
Leftyretro said:
A step down transformer is an important safety isolation component is such an application so I would not give specific information on how to do it without utilizing a transformer.
Lefty
I agree with Lefty's advice:
you need isolation from the 220vAC line.
A "modern day charger or power supply" may be one of two types:
>>> A "traditional" transformer, that is one operating at 50 or 60 Hz, or
>>> A SMPS (Switch Mode Power Supply), like the power supply in a PC, only smaller.
A SMPS
may also provide isolation (and both the "wall wart" ones and the PC ones do that).
You may use a "recycled" one from a discarded cell phone or similar (or even buy one new), but
it is not easy to design, build or ever repair one without taking safety measures. (
If you don't know how to work inside line powered equipment stay away from the supply's innards)
That said, if you have an
isolating supply (like a cell phone's) you can use it's output without danger.
Leftyretro said:
That aside, it is possible, with a properly sized capacitor, to capacitively couple AC voltage to a rectifier/filter/regulator circuit, but again not recommended for safety reasons.
Lefty
This capacitively coupled supplies should be used only inside an enclosure, and you should treat the supply's output as a "hot" circuit like the 220 V line it is connected to.