Problem with CMOS 4066 and LM311N comparator

leeb_965

Feb 5, 2012
34
Hi,

I have built the attached circuit and the simulation works the way I wanted it to. When I assembled it on a breadboard I am getting a square wave at the output instead of a rectified AC signal.

Can anyone suggest why this is? The comparator should switch the CMOS 4066 between a positive and negative cycle.

Attachments

• PSD-CIRCUIT.jpg
30.4 KB · Views: 2,479

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
25,510
What is the amplitude of your input signal?

Can you confirm the amplitude and shape of the signal output from the first op-amp?

Also, you should do something with the other control inputs on the 4066, they shouldn't be left floating.

leeb_965

Feb 5, 2012
34
The input comes a 3-op-amp instrumentation amplifier. I have two AC inputs from a signal generator of 2.91 pk to pk at input 2 at bottom and 2.75 pk to pk at the top to replicate a full bridge circuit

The difference between the two gives 0.16 which is multiplied by the gain of 21

The input to the Phase Senstive Detector is 3.66 pk to pk

The input to the comparator is an AC voltage of 5.66 pk to pk to replicate the AC bridge excitation voltage and act as the reference signal. The square wave output is input into the switch that outputs a rectified AC signal

The simulation works but on the breadboard the output is a square wave.

Do you have any suggestions as to why this is happening? Do you think the other inputs and outputs should be grounded?

Attachments

• PSD-Circ2.jpg
60.4 KB · Views: 1,168

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
25,510
There is some discussion on this page which also talks about the difference between theoretical and practical aspects.

Wabajig

Apr 14, 2012
75
Not sure exactly what your doing. Could you give me specific details of what expect from input voltage and frequency to output. I'm just not getting your application. Unless you got it working, I'm very familiar with these components. Though I don't get on here everyday.

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