# Wrong O/P BY voltage quadrupler in Multisim

Discussion in 'General Electronics Chat' started by Tajiknomi, Oct 29, 2012.

1. ### Tajiknomi Thread Starter Active Member

Mar 18, 2010
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OK, so i'm making a voltage quadrupler, I have supplied 20RMS and i get 27.3DC at output...

i was expecting : 20/0.707 = 28.2V Peak to peak.

quadrupler = 28.2*4 = 112 Approx

But multisim gives me = 27.3.... I have attached Shot herewith..

2. ### Tajiknomi Thread Starter Active Member

Mar 18, 2010
34
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Here is the screen shot

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3. ### crutschow Expert

Mar 14, 2008
19,559
5,452
Your are measuring between the wrong points. You need to measure from the cathode of the right diode to the AC source terminal (the output voltage is the sum of all the capacitor voltages). I measured +109VDC between those two points (it's less than the theoretical because of the voltage drop through the diodes).

In a normal circuit you would make one side of the AC source common and measure between the diode cathode and common.

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4. ### Tajiknomi Thread Starter Active Member

Mar 18, 2010
34
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Thanks... it worked...
One more thing, U said that i should make one side common, in the above circuit, i have Common the Bottom wire...as i have connected a ground... Isn't that mean common ? Sorry for my ignorance... i'm beginner...

5. ### crutschow Expert

Mar 14, 2008
19,559
5,452
Yes, you have the middle of the circuit connected to common (ground). Typically in the actual circuit, one side of the AC input is connected to common instead of where you connected it. That way the output voltage appears between the output and common.

6. ### Tajiknomi Thread Starter Active Member

Mar 18, 2010
34
0
Can i common a single point in a circuit as u described, (In matlab), If Yes, how?

7. ### crutschow Expert

Mar 14, 2008
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5,452
I would think you can, but I'm not familiar with Matlab so don't know exactly how that's done. If you can connect node points together with a node label then you could do that for a node you name "common". Common is just a node voltage point in the circuit, like any other, but is the 0V potential point as referenced to all the other nodes.