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Old 20th Apr 2021, 3:38 am   #18
ortek_service
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Join Date: May 2018
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Default Re: Buffer Amplifier for Digital Frequency Counter

Quote:
Originally Posted by ms660 View Post
15MHz aside, I suspect your schematic needs altering.

EDIT: Just seen the circuit board, the ground plane will be one plate of various capacitors.

Lawrence.
And it looks like on many parts that should have a connection to ground, this ground connection actually only passes through non-clearance holes (and so may only just touch the top groundplane) on the top groundplane to the underside ground track, So they should really be soldered to the top plane, if using a PCB without thru-plating on these holes. Otherwise, ground tracking / planes can be more like a small antenna.
But would probably get away with a lot at HF, as long as transistors can't oscillate at much higher frequencies.
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