230VAC->5Vdc without transformer
Seth Fischer wrote:
> Is there a better or more efficient way of obtaining 5V d.c. with a
> small compact circuit?
Yes, use a series capacitor (mains rated) with a 1/8W (fusible)
resistor in series and a bridge rectifier if the application is not
linked to one mains terminal, or a "voltage doubler"-style pair of
rectifiers if it is.
Note that this arrangement will not allow you to detect the mains
zero-crossing; if you want that you can use a low-power resistor *as
You tell me how much current you need, what ripple you will tolerate,
and I'll give you the (rough) values.
See also: www.piclist.com/techref/power.htm?key=transformer
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