Subject: Re: V regulator input cap size?
Date: Tue, 22 Oct 2002 0:11:24 -0700
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On Mon, 21 Oct 2002 23:15:06 -0700, DaveC wrote
(in message <0001HW.B9DA3AFA00342030163F7590@news.covad.net>):
> On Mon, 21 Oct 2002 16:25:07 -0700, John Popelish wrote
> (in message <3DB48CD0.447092BF@rica.net>):
>> With this ratio of voltage reduction, I would consider a buck
>> switching regulator, unless you have some reason why that would not be
>> You might also consider a prefab DC to DC converter if cost is not so
>> important. It could run off the rectified and filtered 35 volts AC.
>> For example, for $48, Digikey sells an Artesyn CXA10-48S12 rated for
>> 18 to 75 volts in and 12 volts @ .83 amps out. This also provides
>> isolation between the 35 volt transformer and the 12 volt output.
> How about a simple voltage divider across the 35vac liine? Say, divide such
> that one of the resistors has 20 volts across it. It won't be the example of
> efficient use of energy, but the circuit doesn't use more than about 300mA
> at 12 volts.
Or a couple of 10V Zeners in series across the 35v line? (Thanks to Ilpo for
this suggestion.) Dissipates a lot (2W in each Zener) of heat, but...?
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