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i don't get it?


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Hi Bust,
Welcome to our forum. ;D
You can't operate low voltage devices from 120VAC efficiently. I don't see the 2nd AC wire in your circuit so I corrected it, but with 22k resistors then the fan and LED get only about 5mA so the fan probably won't run and the LED won't be very bright.
The 22k resistors will dissipate about 0.64W so better be rated for about 2W so they won't get too hot.

post-1706-14279142460362_thumb.jpg

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hmm, i have another question, see if youv'e come across this. the 22 k in the drwing is like 20 resistors in series, but number wise they add up to 22k but when i measure with a multimeter it says like 40k?!?
I don't get it, do i have to use smaller value resistors to get 22k?

(what i mean is.... paper value is 22k reality value is closer to 40k? why is this... you think i took to long to soder them? because they are surface mount resistors.)

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you don't need a transformer?

Most low voltage electronic circuits use a transformer. Even my soldering iron has one.

i tried to measure my resistance from the positive to the negative... what kind of shocked me is that it measured 10k ohms? short in the bridge?

If your switch is turned off, then you are measuring the resistance of the "resistor series" on your schematic, whatever that is.
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I have some fairly small and very lightweight switching power supplies that have an output of 5V/2A. Cell phones also use a small charger. They use electronic switching tricks instead of a transformer.
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Switching power supplies do use transformers, all switching regulators that have an isolated output use a transformer, the only differance is it's a smaller ferrite transformer that operates at a higher frequency typically 50kHz to 500kHz.

Correct! :-[
The transformer is so small I could hardly see it. It has tiny surface-mount Mosfets driving it.
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lookes like i have to do more research on these transformers -
:'(
the reason i could not fit an iron core transformer (the normal size ones) is that i have a very restrictive area, can not  fit much more than wires, the fan and led have cutouts in the frame, would not look nice or professional if it had a transformer hanging out....

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