The different shape caused the different function. I have some difficulties in reading the sinusoidal signal.
1. When I connect it to oscilloscope, it works correctly, but when I connect to the ADC port, the signal is dropped.
I then cannot read the signal by serial port computer, so I do by oscilloscope.
2. When I generate a square signal more than 5 volts, then connect to ADC port, the amplitude of signal is cut be 5 volts. But I am still able to read it by oscilloscope and by serial port computer.
Anybody have an advice for me to solve this issue?
Maybe I need to build a signal conditioner?
Hello Maizal,
From your explanation above, it is apparent that there is a loading problem with the ADC circuit.
Kindly pay attention that an oscilloscope has a very high input impedance and that is why you can observe the waveform clearly. When you are connecting it to your ADC circuit there is a loading effect.
So add a simple op-amp based buffer first to see if there are any improvements.
Best Luck!
Thank you very much Sir. I have been try. Its work, but the signal shape was change. Its not pure sine wave. I see the distortion there. I use AD620 with gain 1 (buffer).
Maizal,
Good that some positive developments are there. I would appreciate if you could upload me with the pictures of 1) the actual signal output as seen on an oscilloscope and second when you put your circuit into it - i.e. input and output of the buffer stage.
One more important fact I would like to suggest you is that if you are working with square wave in excess of 5V (TTL Level) ensure that it is attenuated first to a lover level either by a voltage divider or a zener protection so that it does not cause any harm to your digital circuits.
Best Luck!
Hello Maizal,
Just as a matter of curiosity I would be happy to know if you are successful in your experiment or what is the status as of now?
Thanks and good luck!
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