[time-nuts] need power trans. for HP3325

[John Miles]

> I work for a company that designs and builds switchmode power supplies,
> so I have access to lots of power supply and filter components

Man with hammer says: "Mmmm, nails!"

> It has been a long time since I have seen an SCR preregulator. They have
> almost the same complexity as a switcher (from a parts count
> standpoint), without any of the advantages, other than slightly lower
> noise levels at higher frequencies. However, they are bad for line noise
> (conducted emissions) and power quality (power factor, harmonic
> distortion) and require oversized transformers, inductors and
> capacitors, even compared to a normal linear supply. These are now
> completely abandoned (except maybe at very high power levels, as used in
> industrial processes and I believe in rail transportation) because they
> can't meet the power quality requirements and they cost too much/are too
> big and heavy.

Conduction-angle preregulators were used in some of the HP/Harrison benchtop
power supplies (my 6263B has one), as well as some of the smaller Carver
audio amplifiers in the 80s.  Definitely one of those 'dead-end' branches of
the great evolutionary tree of electronics...

-- john, KE5FX