I have used that trick also for HV supplies when leakage through a capacitor
(typically the capacitor used to compensate the HV divider used for regulation)
exposed to 10 or 20kV is hard to eliminate.
At the time, I did not know it had already been invented...
Didier KO4BB
Sent from my BlackBerry Wireless thingy while I do other things...
-----Original Message-----
From: "Poul-Henning Kamp" <p...@phk.freebsd.dk>
Sender: time-nuts-boun...@febo.com
Date: Thu, 05 Jan 2012 22:49:55
To: Discussion of precise time and frequency measurement<time-nuts@febo.com>
Reply-To: Discussion of precise time and frequency measurement
<time-nuts@febo.com>
Subject: Re: [time-nuts] Thunderbolt? (re simple gpsdo.) >> capacitors
In message
<CAL8XPmO76XuTETZC=33_v2YWuJGcw8gCvtTDHyae6E4MFb18=g...@mail.gmail.com>
, Azelio Boriani writes:
>I have googled extensively trying to find something about the dual
>capacitor method of reducing the leakage current... nothing found. Please,
>can you indicate anything for me to learn more?
It is very simple:
R1 charges C1 to the DC potential and therefore C2 sees
(almost) no DC voltage, which means (almost) no leakage
current. C2 is still a capacitor for any AC or dV component.
I belive I picked this trick up from a datasheet or app-note relating
to precision voltage references.
Poul-Henning
>> [Some op-amp] >-+-----R2-----+-->
>> | |
>> | ----- C2
>> | -----
>> | ____ |
>> +---|____|---+
>> R1 |
>> |
>> ----- C1
>> -----
>> |
>> GND
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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