I've also been thinking about this problem and the reason I'm not keen
on a DC regulator is that the distortion and peak current of the mains
current waveform is already pretty bad with a capacitor input B+ supply
and making it worse by adding the heater as well will undoubtedly make
the regulation of the B+ worse. This is particularly a problem when
using portable generators.
I've not taken this down to circuit level yet but my idea was to use one
of the Analog Devices RMS to DC convertors as its important to maintain
the RMS of the AC constant - especially when using poor quality mains
from a generator. Hsu - this is the problem with your circuit. My
other idea was to use a biphase rectifier with a centre taped
transformer and schottky rectifiers to reduce the diode losses - which
are quite significant with a 5 V heater.
73 John G3UUT
On 10/07/2011 03:03, Dr. David Kirkby wrote:
> On 07/10/11 01:12 AM, Hsu wrote:
>> I do not think a DC regulator for direct heater tube is a good idea,I draw
>> a block diagram for AC filament regulator
>> here:http://www.zmdz.com/bbs/incomefiles/20117/1089098780.JPG, just a block
>> diagram.any advice? I know we have another selection,CVT. a special
>> transformet.
>> 73!Hsu
> What's wrong with a DC regulator?
>
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