From: "Frank Bemelman"
References: <0001HW.B9D991AD000C5917163F7590@news.covad.net> <firstname.lastname@example.org> <0001HW.B9D9CD54001A5D15163F7590@news.covad.net> <3DB48CD0.447092BF@rica.net> <0001HW.B9DA3AFA00342030163F7590@news.covad.net> <4y97qUAX7Qt9EwBY@jmwa.demon.co.uk>
Subject: Re: V regulator input cap size?
Date: Tue, 22 Oct 2002 17:52:32 +0200
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Organization: EuroNet Internet
NNTP-Posting-Date: 22 Oct 2002 15:54:21 GMT
"John Woodgate" schreef in bericht
> I read in sci.electronics.design that DaveC wrote (in
> <0001HW.B9DA3AFA00342030163F7590@news.covad.net>) about 'V regulator
> input cap size?', on Mon, 21 Oct 2002:
> >How about a simple voltage divider across the 35vac liine? Say, divide
> >that one of the resistors has 20 volts across it. It won't be the example
> >efficient use of energy, but the circuit doesn't use more than about
> >12 volts.
> >Is this a do-able solution?
> Well, sort of, but you get lots of heat. Is the 300 mA constant? If so,
> you can simply put a resistor in series with the bridge rectifier, on
> the AC side. This also changes the operation of the rectifier to more
> nearly a current-fed type. You would need to drop 20 V at around 500 mA,
> which is 40 ohms, 10 W. Not elegant, but possible.
I understood the relay used 200mA (at 12V) so it is not constant but
depends on the relay on or off. A dummy load of 60ohm, driven via
inverted logic, could make the current more or less constant.
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