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From: "Frank Bemelman"
References: <0001HW.B9D991AD000C5917163F7590@news.covad.net> <firstname.lastname@example.org> <0001HW.B9D9CD54001A5D15163F7590@news.covad.net> <0001HW.B9DAE8B7003F6E14163F7590@news.covad.net> <3DC1A954.email@example.com> <1%hw9.136243$Q3S.firstname.lastname@example.org> <3DC1AF48.email@example.com> <firstname.lastname@example.org> <3DC1D9F4.email@example.com> <3DC1E2EC.firstname.lastname@example.org>
Subject: Re: V regulator input cap size?
Date: Fri, 1 Nov 2002 14:18:38 +0100
X-Newsreader: Microsoft Outlook Express 6.00.2600.0000
Organization: EuroNet Internet
NNTP-Posting-Date: 01 Nov 2002 13:23:38 GMT
"Fred Bloggs" schreef in bericht
> Spehro Pefhany wrote:
> > In sci.electronics.components Fred Bloggs wrote:
> >>You must be thinking of ACV relays, the DC relays don't leave a lot of
> >>room. They have a real bad spread on pull-in voltage and it gets higher
> >>with temperature by quite a high percentage by the time you hit 70C. If
> >>you want save a current source then you could do something like this
> >>where the capacitor guarantees turn-on and then the DC value settles
> >>down to safely below over-voltage:
> > When you figure in the darlington drop, the two diodes in the bridge and
> > the small capacitor, that's effectively what my circuit does. You can
> > adjust the steady-state voltage boost (over the RMS input less three
> > drops plus) by changing the capacitor value. It has to be able to
> > withstand a lot of ripple, but typically high-voltage low capacitance
> > electrolytic caps don't have a problem with that.
> It does? Yikes- I wouldn't bank on any particular value of capacitance
> in an electrolytic that way, and I don't see the transformer voltage
> dropping much for a 25mA load. And you are now adding high peak
> rectifier current spikes to the equation.
Gentlemen, I'd like to see some *results* now. Either that or find a
new career as a shoe-salesmen.
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