The Cyber-Spy.Com Usenet Archive Feeds Directly
From The Open And Publicly Available Newsgroup
This Group And Thousands Of Others Are Available
On Most IS NNTP News Servers On Port 119.
Cyber-Spy.Com Is NOT Responsible For Any Topic,
Opinions Or Content Posted To This Or Any Other
Newsgroup. This Web Archive Of The Newsgroup And
Posts Are For Informational Purposes Only.
From: Fred Bloggs
User-Agent: Mozilla/5.0 (Windows; U; Win 9x 4.90; en-US; rv:1.0.1) Gecko/20020823 Netscape/7.0
X-Accept-Language: en-us, en
Subject: Re: V regulator input cap size?
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>
Date: Fri, 01 Nov 2002 02:11:20 GMT
NNTP-Posting-Date: Thu, 31 Oct 2002 18:11:20 PST
Organization: EarthLink Inc. -- http://www.EarthLink.net
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 diode
> 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.
Go Back To The Cyber-Spy.Com
Usenet Web Archive Index Of
The sci.electronics.design Newsgroup