# Full Wave Rectifier

Discussion in 'Homework Help' started by ac_dc_1, Jan 30, 2013.

1. ### ac_dc_1 Thread Starter Member

Jan 27, 2013
74
0
I am trying to analize this rectifier.I want to determine the expressions of the ouputs and the gain of both Amps and of the montage

VO1= 0V if Vi>0V

For the second OpAmp

Vo2=-R5/R3 Vout 1 - (-R5/R4)Vout for Vin<0 V

and Vo2=-R5/R4*Vin if Vin>0 V

Thanks

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Last edited: Feb 6, 2013
2. ### Audioguru Expert

Dec 20, 2007
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1,200
The circuit works very well when the opamps have a positive and negative power supply.
The first opamp circuit produces only the negative parts of the input. Its level is doubled by the second opamp and added to the input signal then some of the positive cancels the negative and produces full-wave rectification.

3. ### ac_dc_1 Thread Starter Member

Jan 27, 2013
74
0
So the second opamp has a gain of 2,rigth?

4. ### Audioguru Expert

Dec 20, 2007
10,726
1,200
The second opamp has a gain of 20k/10k (R5/R3=2) for the half-wave rectified signal from the first opamp and it has a gain of 20k/20k (R5/R4=1) for the input signal.

Then when the input signal goes negative one amount the output of the second opamp goes positive two amounts which cancels the negative leaving a signal level of positive one.

5. ### ac_dc_1 Thread Starter Member

Jan 27, 2013
74
0
So in conclusion Vo=-vi if Vi<0 and Vo=Vi if Vi>0

6. ### thatoneguy AAC Fanatic!

Feb 19, 2009
6,349
730
Work out what the voltages would be if the input was +5VDC

Do the same, but with an input of -5VDC

From there, you'll have a good understanding of how the circuit works.