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Hello, please could anyone tell me whether there is any way to test that R6 is set correctly following full construction (apart from detaching the components added in step 8 and 9)? I presume measuring voltage at TP4 is no longer an option (I get a reading of +700mV)?
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You should set the Reject pot to minimum and adjust R6 to place the start of the main sample at the required minimum. For example, you may want the main sample delay to start at 10us. You will need an oscilloscope to do this.Originally posted by JOHNCGRAY View Post
If you don't have a scope available, then the only other way is to calculate the desired minimum sample delay and adjust R6 to a specific resistance.
The delay value is set by the values of R6 and C8. The absolute minimum delay is determined by U6. In my tests I could not get the delay below 7us, as the pulse would just vanish.
Let's say you want the minimum sample delay to be 10us:
Then 10us/220pF = 45.5k.
Then all you have to do is adjust R6 to a value of 45.5k. -
Thank you for this, much appreciated. I have a scope but will have a play with both approaches. What would be the observed detrimental effect, should the R6 be 'out' ?Comment
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You can leave R6 in-circuit if you disconnect the external reject pot when measuring the resistance of R6.Originally posted by JOHNCGRAY View PostComment
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