Reduce the voltage supply 230 VAC to a DC voltage transformerless

Figure 1: Diagram of the circuit without power transformer and component list.

Here's a good time that I manage to get the low voltage I need for my movies directly from the 230 V without using a transformer component heavy, bulky and expensive ... at least for my scholarship student IUT!
I replace the transformer reducing voltage by the capacitive reactance phenomenon: you know that when AC voltage is applied to a capacitor in series, it offers resistance to current flow (the reactor).
This resistance value R (in ohms) is based on the capacity C (uF) and the frequency F of the AC voltage (Hz), using the formula:

R = 159 000 (F x C)

In my circuit I built two capacitors of 1 uF 250 V series, making a total capacity of 0.5 uF; with the mains frequency 50 Hz, the resistive value of these capacitors will be:

159 000: (50 x 0.5) = 6360 ohms or 6.36 k.

I put two capacitors in series of 250 VDC operating voltage, which divides the two but double capacity by the voltage (that is to say continuous use without problems) and is therefore at 500 VDC.
Also in series with the voltage of 230 V, I added a resistor of 56 ohms 1 / 2 W as protection for the entire circuit.
I go out in a 1 W zener with a rated voltage is slightly higher than the voltage that I would get: for 12 V I choose a zener of 15-16 V to avoid that in the absence of load voltage not skyrocketing. To obtain an output voltage of 9 V I would choose a 10 V zener
I'm sure this little montage of interest to other electronics enthusiasts like me.

Component List
R1 ..... 56 1 / 2 W
C1 ..... 1 uF 250 V polyester
C2 ..... 1 uF 250 V polyester
C3 ..... 220 uF electrolytic 25-33 V
DZ1 .... Zener 1 W (see text)
RS1 .... 250 V rectifier


Editor's Note
fails to mention that this power is directly connected to a power of 230 V, if someone touches any part of the circuit when it is turned on, he will receive an electric shock can be fatal.
You should know also that it will not be obtained in this way a current exceeding 15 to 20 mA.
The reader may realize that a perforated plate mounting tape or pelletized, and may also practice drawing a real circuit board (it's very easy method to see the film Blue in Issue 26 of ELM or alternatively ask our advertisers).
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