I'm kinda new in this and I was wondering if I could get some help.

I am trying to build a AC-DC converter, through a full wave rectifier. Ideally a 220V AC source, freq: 50hz stepped down to 22V AC and rectified to a DC voltage but I'm struggling to get a definite formula to calculate the smoothing capacitance. I was planning to channel the output of the rectified DC to a 7812 voltage regulator. Thanks in advance.

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    \$\begingroup\$ If you would have just searched this site you could have found: electronics.stackexchange.com/questions/176661/… \$\endgroup\$ Commented Aug 31, 2016 at 9:09
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    \$\begingroup\$ 22V AC when rectified will give you about 30V DC. The 7812 will have to drop 18V which may cause overheating if you draw any significant current from it. \$\endgroup\$
    – Steve G
    Commented Aug 31, 2016 at 9:19
  • \$\begingroup\$ @ Steve G, correct me if I'm wrong but if I was rectifying 22 AC, I would get about 15.55V by using the formula, Vpeak x 0.707? \$\endgroup\$
    – Iskandar
    Commented Aug 31, 2016 at 9:28
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    \$\begingroup\$ AC voltages are normally specified by their RMS, rather than peak, value. Thus the peak is 22 sqrt(2) ~= 31 V, minus a diode drop or two due to rectification and whatever additional drop is acceptable due to load current and the limited size of the smoothing capacitor. \$\endgroup\$ Commented Aug 31, 2016 at 9:36
  • \$\begingroup\$ @ Oleksandr, thanks man!, I didnt know that, i really have to brush up on my fundametals then. \$\endgroup\$
    – Iskandar
    Commented Aug 31, 2016 at 9:41


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