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Transformer

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sardineta

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I would like to know how this power transformer can be used to do a dual power supply of + / - 12 volts.

I have worked with a transformer with three cables at the secondary but this has 4, can you please help me?

how the cables should be connected to do the power supply?

Also

How I eliminate a TRANSIENT VOLTAGE, how I filter the input signal (120Vac) because when I turn on a flourescent lamp or I connect a electronic device I have noise in the ground path or my electronic design that my microcontroller (PIC16F870) reads a bad signal.

I am planing to put a varistor and a ceramic capacitor of .1uF in parallel between the AC man line. is it right?

Thanks in advanced, happy new year!
 

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short 6 and 7 together to make local GND point
 
Thanks a lot!!!

Here is the configuration, so what other devices would make my power supply more robust.

I have some troubles with a noise that appear when a device is connected or unplugged. The ADC of the uControlled read this false alarm and then actives a relay when the set point is less that the incomming singal.
 

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Apply this filter in primary side. Or buy a mains socket with in-built filter...
 

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Sebi
thanks a lot, I wil probe the recommendations you gave me.
I will look for them!
by the way, I have no idea hot to ask for the inductosr and the capacitos
I mean what does 100nx2 means?
I suppose it is a capacitor of 100nF@250Vac
and the 2x12mH how it is?

Do you have the part numbers or the commercial values/names?
how I ask for them?


Russlk

in the circuit what will you do?

In the protoboard I just connect the micro and two leds and the noise is always there!

what can I do?
 
It looks like the primary wires are radiating to the circuit. Sebi's filter should solve the problem. The two coils are coupled and are 12mH each (12X2). Each capacitor is 100nF and there are two of them (100nX2). I don't know why the capacitors are named twice. You can buy a power filter that has all inside.
 
Russlk

Thanks, I think this can be done in the final circuit, however which can be more efficient, the power filter or the one I will assembly in the circuit board?
 

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Yesss! Exactly these parts what You need.
BTW: the 100nF X2 is a type of capacitor, not*2. X2 type designed for AC 50 (60) Hz use.
 
If you put the components on the board, there could still be radiation to the logic circuits. The "inlet filter" shown is shielded and will prevent that radiation. The center wire should show continuity to the case and should be connected to circuit ground.
 
Russlk, Sebi

that sounds great, but space consuming on the board if the inlet filter is used. About it, the cable EARTH needs to go to the common ground of the digital circuit or to the case.

CA1 and CA2 goes to the power transformer
eart to where?

mmmm I found a inlet filter with different characteristics than the one you recommend me, and I still see the spikes (more short), probably the inlet filter has to be in the opposite direction, of all the circuits, isn't it?

I found another inlet filter
it is a DUAL T section RFI power line Filter
1VR1 1A 15.67 dlls from corcom
comments: "well-suited impedance loads where noise RFI environments are present, units control pulsed, continuous and/or intermittent interference , assuring protection of equipment from power line noise while also protecting the from equipment noise.

https://www.newark.com/NewarkWebCom...y=1&showImages=true&N=4&Ntk=gensearch#results

any comments?
 

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final power supply

Russlk

What you mentioned about the central wire is like the figure.
(Sorry for too many questions but I do not want to blow-up the circuits)


thanks in advance!
 

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