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Vahab
Joined: 08 Apr 2007
Posts: 17
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 04 Dec 2008 16:55 RMS Detector |
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Hi all,
I want to find suitable circuit for measurement RMS value and convert it to DC.
please help me.
It is important for me and i'm waiting to you.
Good Luck
vahab
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FvM
Joined: 22 Jan 2008
Posts: 5161
Helped: 767
Location: Bochum, Germany
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04 Dec 2008 19:02 Re: RMS Detector |
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See:http://www.national.com/an/LB/LB-25.pdf
The circuit may be build with cheap CA/LM3046 transistor arrays if the maximum collector current is reduced to 1 or 2 mA.
IC's implementing the same operation principle are available too.
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LvW
Joined: 07 May 2008
Posts: 1466
Helped: 242
Location: Germany
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04 Dec 2008 20:27 Re: RMS Detector |
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Hi Vahab,
there is another quite simple solution involving a multiplier/divider IC (as far as I remember AD435) and a simple buffer circuit. Please give notice if you are interested.
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04 Dec 2008 20:27 Ads |
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Awarapunshee
Joined: 11 Jul 2007
Posts: 455
Helped: 60
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05 Dec 2008 6:11 Re: RMS Detector |
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Analog Devices AN212 Application Note is also good to have a look.
ENJOY!
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FvM
Joined: 22 Jan 2008
Posts: 5161
Helped: 767
Location: Bochum, Germany
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05 Dec 2008 7:58 RMS Detector |
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| Reviewing this classical document, I was aware that Vahab actually didnt't mention if the application is kHz or MHz domain. For low frequency (e. g. audio) range, a log/antilog circuit, either as an IC or built from individual parts, is offering superior dynamic, for high frequency, only gilbert-cell multiplier circuits or thermal detectors are usable.
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