Urgent!! (i want to create a full wave rectifier}

Thread Starter

Halim.Akiki

Joined Dec 29, 2014
44
Hello
I have a small project and i want to create a full wave rectifier. I drew the following circuit
But i am having a negative result

Can anyone help me?
The sine wave is :
DC = 0 V
AC = 16 V
VOFF = 0 V
VAMPL = 16 V
FREQ = 60 Hz
 

WBahn

Joined Mar 31, 2012
30,028
What size resistor did you use? How can we give good feedback if you don't give us the information?

Since your output appears to be drooping from 14V down to 1V and that is being pulled from a 0.83uF cap, that means that you are pulling about 11uC of charge from it. Since that is being pulled out in 1/120th of a second, that's an average current of about 1.3mA. Since the average voltage is about 6.5V, I'm going to guess that you are using something like a 5kΩ resistor. Is that close?

If you follow how I did that, then see if you can work backwards to find a good capacitor value to use to keep the droop (also known as ripple) below a desired value.
 

Thread Starter

Halim.Akiki

Joined Dec 29, 2014
44
What size resistor did you use? How can we give good feedback if you don't give us the information?

Since your output appears to be drooping from 14V down to 1V and that is being pulled from a 0.83uF cap, that means that you are pulling about 11uC of charge from it. Since that is being pulled out in 1/120th of a second, that's an average current of about 1.3mA. Since the average voltage is about 6.5V, I'm going to guess that you are using something like a 5kΩ resistor. Is that close?

If you follow how I did that, then see if you can work backwards to find a good capacitor value to use to keep the droop (also known as ripple) below a desired value.
Man you're a genius!
 

Thread Starter

Halim.Akiki

Joined Dec 29, 2014
44
Wouldn't go anywhere near that far, that's for sure. But thanks anyway.

What size resistor were you using?

Did that help you size your capacitor better?

What was the final result?
I was u sing a 1K resistor. increasing the capacitor's size to 10mF made the result perfect.
 

WBahn

Joined Mar 31, 2012
30,028
I was u sing a 1K resistor. increasing the capacitor's size to 10mF made the result perfect.
Yeah, in increase by a factor of 10,000 probably reduced your ripple voltage for that size load down to a millivolt or two. It will give you a pretty high inrush current, though.
 
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