# does the cell phone charger include an oscillator ?

#### zaki.097

Joined Jun 11, 2017
3
hello
i want to build a cell phone charger and i have a small transformer so i need to increase the frequency of 220v/50hz to higher frequency and in order to do that first i rectified the 220v ac and used a 2uf capacitor then i am confused ho to have a square wive od even a sine wave and then decreased the voltage with my small size transformer to around 10 volt
so my question is that do i have to use an oscillator or what and thank you

#### Alec_t

Joined Sep 17, 2013
11,398
Welcome to AAC!
Messing with mains voltage is very dangerous, and constructing a SMPS is far from easy, particularly if you are inexperienced.

ak

#### ian field

Joined Oct 27, 2012
6,539
Yes, they do.

ak
There's still a *FEW* iron cored transformer chargers about that don't.

They're rapidly becoming extinct though.

#12

#### #12

Joined Nov 30, 2010
18,210
There's still a *FEW* iron cored transformer chargers about that don't.
They're rapidly becoming extinct though.
I have a few iron core wall warts, but they are so old that it's difficult to read the manufacturing date codes on them.

#### AnalogKid

Joined Aug 1, 2013
8,487

#### WBahn

Joined Mar 31, 2012
25,911
I have a few iron core wall warts, but they are so old that it's difficult to read the manufacturing date codes on them.
Did they even use the Gregorian calendar back then?

#### #12

Joined Nov 30, 2010
18,210
Did they even use the Gregorian calendar back then?
Some of them don't. I've seen Julian calendar date codes.

#### WBahn

Joined Mar 31, 2012
25,911
Some of them don't. I've seen Julian calendar date codes.
Good point.

I got curious about why it is called "Julian" since, in my experience, it is generally the last digit of the year followed by the three digit day of the current year. I didn't think that any ancient calendars counted days since some year-defining event, but maybe.