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Below are all of the forum threads, including all
the responses to the original posts.
Post subject: Setup question for signal source and buffer Posted: Fri Oct 27, 2006 11:10 am
Joined: Fri Apr 07, 2006 6:10 pm
I need your practical opinion from
experience, if any. I have a signal source. Part of this signal needs to be sampled. One sampling process involves
detecting whether the signal is there or not. Another sampling process will try to detect whether the signal
amplitude has surpassed a certain threshold.
Just assume that the signal is a low frequency signal at 38
Would it be optimal to do the following setup?
- use a quad opamp package and configure three
of the opamps as voltage buffers / follower.
- tie the input of the three opamps to the same node
the signal source to this common node
The first opamp would just replicate the signal source and send it
unprocessed. The 2nd and 3rd opamp would do the sampling processing schemes.
Does this sound right?
Or would it be ok to skip the buffer setup and directly interface the signal source to a common bus that branches
off directly to the sampling sections? This is assuming that the two sampling schemes utilize op amp inputs to do
the signal detection and peak detection. Thanks!
Post subject: Posted: Fri Oct
27, 2006 11:22 am
Joined: Fri Feb 17, 2006 12:07 pm
At such a low frequency, I would have the first OA as a voltage follower/buffer.
The output would go to
the second stage as a full-wave detector with a time constant well in excess of the carrier cycle time (ie LPF).
The output would split two ways.
One way to a Schnitt Trigger to act as the "Signal/NOT signal" output, with
the trigger level set just above noise (assuming this level is predictable).
The second way would be to another
Schmitt Trigger with an adjustable trigger threshold set to whatever level you are looking for.
If only we
had a simple Drawing Tool.