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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets. |
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3rd Mar 2023, 2:36 pm | #1 |
Triode
Join Date: Sep 2020
Location: Athens, Greece
Posts: 21
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Level selective amplifier circuit needed
Dear all,
I wonder if a level selective HF amplifier circuit exists out there. An amplifier that amplifies more the high level signals above a settable threshold and less (if not at all) the low level ones. This is not the same as a squelch circuit, but rather exponential level amplification. Any help towards this direction, would be much appreciated. Thank you |
3rd Mar 2023, 6:57 pm | #2 |
Octode
Join Date: Dec 2019
Location: Owston Ferry, North Lincolnshire, UK.
Posts: 1,689
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Re: Level selective amplifier circuit needed
I thought thats what graphic equalisers were designed to do having several frequency set ranges, perhaps I misunderstood the question.
Dave
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3rd Mar 2023, 8:48 pm | #3 |
Moderator
Join Date: Mar 2012
Location: Fife, Scotland, UK.
Posts: 22,801
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Re: Level selective amplifier circuit needed
No, it's not a graphic equaliser, it's actually an expander, AGC achieving the opposite effect - increasing the variation in input signal level.
I can't think of a use for one. David
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3rd Mar 2023, 9:15 pm | #4 |
Heptode
Join Date: Jul 2018
Location: Worthing, West Sussex, UK.
Posts: 983
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Re: Level selective amplifier circuit needed
You would need a level detector driving a comparator and some switching, or maybe something more elegant.
Are you asking for an expander/noise gate? What is your intended use?
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4th Mar 2023, 9:14 am | #5 |
Hexode
Join Date: Oct 2014
Location: Wiltshire, UK.
Posts: 378
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Re: Level selective amplifier circuit needed
An OpAmp with a PN junction in the feedback path has a transfer function which is either logarithmic or exponential depending on where you place the diode. This was used a lot in the days of analogue computing, it has the disadvantage of poor temperature stability in its simplest form. Is that anywhere near what you need?
Roger |