[Milsurplus] [ARC5] If You Need a Regulated Low B+ Supply

[J. Forster]

Not at all.

If you want regulation, there are a number of ways to do it. IMO, the
simplest would be a FET or BJT version of the "Beta-C" circuit with the
capacitor replaced with a Zener or Zener string.

You could also regulate the inverter input and feed back an output sample.
Isolation of the B- line is usually not needed, unless you are stacking
supplies. Some exceptions are the R.1155 and WS19 HT2.

-John

===============



> True, you can slow switch at 60Hz but if dynamic load regulation matters
> it
> can become an issue.  You would have to rely purely on big oversized caps
> vs
> the feedback loop to hold the voltage steady in the presence of CW or
> voice
> peaks.
>
> Dennis AE6C
>
>
> On Sun, Feb 14, 2010 at 11:14 AM, J. Forster <jfor at quik.com> wrote:
>
>> One solution to the EMI problem from switchers is to use a low frequency
>> square waves, of the order of 60 Hz, rather than 10s of KHz. This
>> enables
>> you to use much slower rise/fall switching times and conventional
>> filament
>> transformers run backwards. They are bigger and require bigger HV caps,
>> but are a lot quieter.
>>
>> Best,
>> -John
>>
>> ================
>>
>>
>>
>>
>>
>> > While the diagram says "new" this part and the associated circuit
>> dates
>> to
>> > 1991 when it went into the early GM airbags.  I know because my work
>> group
>> > designed it.  However, it is still sold along with a plethora of other
>> > "Simple Switchers" which have gone through five generations now.  If
>> you
>> > go
>> > to the National Semiconductor website you will a cluster of
>> easy-to-use
>> > design tools that allow virtually anyone to design the switching reg
>> they
>> > need right on-line.  All the popular configurations are covered.  You
>> can
>> > then order the components along with the PCB from the distributor link
>> or
>> > just roll your own by buying the chip from DigiKey.
>> >
>> > BTW, you can still stack "common-ground" DC/DC converters by feeding
>> them
>> > raw DC from independent windings on the transformer.
>> >
>> > Remember that most switcher circuits are not designed to have low
>> enough
>> > EMI
>> > to guarantee happiness in our radios.  Pay close attention to short
>> lead
>> > dress, good grounding and use shielded inductors vs the cheap solenoid
>> > types.  For best results, extra input & output filtering and a metal
>> box
>> > may
>> > be needed.
>> >
>> >
>> > Dennis AE6C
>> >
>> > On Sat, Feb 13, 2010 at 11:50 AM, David Stinson <arc5 at ix.netcom.com>
>> > wrote:
>> >
>> >> This cute little circuit is an example of the kind of DC/DC
>> >> converter you cannot stack, since in and out have a
>> >> common ground:
>> >>
>> >> http://www.nbglin.com/dc.htm
>> >>
>> >> Still a neat circuit, though.  I'm gonna get me a
>> >> couple to use as "Borg Implants."
>> >>
>> >> 73 Dave S.
>> >>
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>>
>>
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