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KnobHell
Joined: Jan 28, 2012 Posts: 56 Location: SLC
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Posted: Tue Jul 10, 2012 5:40 am Post subject:
Sample And Hold With VC-Clock Questions |
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Hi,
Do Q1 and Q2 the 2N3904's need to be matched?
Are there any changes to operate from 15 volts?
Thanks!
len |
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Feifer
Joined: May 16, 2012 Posts: 54 Location: San Diego
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Posted: Tue Jul 10, 2012 9:36 pm Post subject:
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Hey Len,
No need to match to match those I think. Matching transistors like in this case is really only necessary if you want to improve tracking through 1V/oct, which for the sample rate of a S/H to me seems silly. Although someone out there might have a use for it.
You will have to change some resistor values if you use 15V. The obvious places are where you have reference voltages via a divider. See R25, R26. Unless someone chimes in with it all worked out already, I would suggest breadboarding first. |
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KnobHell
Joined: Jan 28, 2012 Posts: 56 Location: SLC
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Posted: Wed Jul 11, 2012 7:52 am Post subject:
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Feifer wrote: | Hey Len,
No need to match to match those I think. Matching transistors like in this case is really only necessary if you want to improve tracking through 1V/oct, which for the sample rate of a S/H to me seems silly. Although someone out there might have a use for it.
You will have to change some resistor values if you use 15V. The obvious places are where you have reference voltages via a divider. See R25, R26. Unless someone chimes in with it all worked out already, I would suggest breadboarding first. |
Thanks Feifer.
Certainly, if anyone had built this for 15 volts please let me know which mods worked for you.
len |
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