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Coupling capacitor between two circuits

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Newbie level 3
Apr 19, 2008
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I design an inductorless Chua circuit based on the design found in
**broken link removed**
and by replacing the LMC6482AIN opamp by TL081

The circuit works but when I tried to connect the output with comparator (open loop TL0821 opamp or LM311) the output signal was vanished.

I tried to couple the two circuit with coupling capacitor using trial and error for the values. At C=110nF is threshold. below this value the random signal work but no output at the comparator. Above this value the random signal changed to periodic sine wave which is not required.

My question: how can I design coupling capacitor between the two circuit to generate random bits?

Thanks a lot

The TL08x opamp is COMPLETELY DIFFERENT to an LMC6482 opamp.
Why didn't you use the proper opamp?
The schematic is cut off by the scope photo so I cannot see if the opamps have proper biasing.

how can I .... generate random bits?

If this is what you want, then the best way is to use a pseudo-random sequence generator, PRSQ.

Is this for BER testing?
If so what bit rate and length of pattern ?

There are many different lengths using prime number of shift registers for Maximal length PRSG designs using shift registers and XOR gates.
**broken link removed**
Here is a simple short 8 bit random bit generator 2^8-1 or 255 byte pattern sequence . You can reset to start with same pattern or use random seed with more logic, then compare Tx with Rx for error detection and then count number of consecutive error free bits between errors to plot probability of error or BER in log-log scale.

Not all details are shown for initial condition but this is a 2^9 byte pattern **broken link removed**

more info

By giving more purpose to your question, a better answer may come to mind.

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