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The recent post by Eclipse enquiring about the 'Compensating Pulse', prompted me to look through my old notebooks from 1970's. In 1976 there was a couple of pages describing an auto-zero circuit that I tried, and which had some interesting properties. As you can see on the second page it causes the output of the first amplifier to pivot around the point where the sample is taken when a metal target is introduced. The 709 generates a negative waveform that decays upward to zero for short/medium decays, while long decays cross over to give an additional positive response when beyond the mid point of S2.
Extending this idea and the introduction of another later sample gate/integrator channel gives the possibility of separating decays into short and long categories, particularly if the auto-zero sample S2 is moved closer to S1. Further to that, maybe we have the basis of a simple ground balance arrangement where the pivot point S2 is moved to a point near S1 such that the sample amplitude is the same as for that at the 3rd gate (S3) and then subtracted. This has not been tried as yet, but could be easily tested; with modern devices, of course.
Eric.
Extending this idea and the introduction of another later sample gate/integrator channel gives the possibility of separating decays into short and long categories, particularly if the auto-zero sample S2 is moved closer to S1. Further to that, maybe we have the basis of a simple ground balance arrangement where the pivot point S2 is moved to a point near S1 such that the sample amplitude is the same as for that at the 3rd gate (S3) and then subtracted. This has not been tried as yet, but could be easily tested; with modern devices, of course.
Eric.
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