Re: Todds and Vicors (Was DC>DC Converter?)

[Lee Hart <leeahart@earthlink.net>]

John Wayland wrote (on Vicor DC/DC converters):
> they do work, but somehow, someway, Vicor always makes their converters
> to be the most un-user friendly devices I've ever seen...

You have to remember that the Todds are finished products. You buy it
and use it exactly as-is. Vicors are a component part, like an
integrated circuit, and intended to be soldered onto a printed circuit
board with the rest of the filters, fuses, voltage set pots, transient
absorbers, input and output connectors, heatsink, etc. 

Vicor does sell socket pins, so the modules can be plugged into a PC
board. They also sell the "BusMod", which is a big socket for one VI-200
series DC/DC.

The Vicors are expensive, because they are built to higher standards.
They are more efficient, generate less noise, have higher voltage and
current regulation accuracy, and are potted so water will not hurt them.

If you wanted a Vicor equivalent of a Todd PC30:

1. Open the case of a PC30. Note there are 3 PC boards; one filter-
   rectifier board in the center, and two DC/DC converter boards, one
   on each side, with their inputs and outputs wired in parallel.

2. Remove the two DC/DC converter boards.

3. Replace them with two VI-200 modules with 150vdc input, 15vdc @ 200w
   output. One should be a "master" module, and the other a "booster".

4. You also need to wire one pot and one resistor to the voltage
   trim pins, so you have a way to set the output voltage.

At this point, you have an exact replacement for the PC30. But, it is
water resistant, lighter, more efficient, runs cooler, generates less RF
interference, can deliver more current, and has a more stable output
voltage. Yes, it costs more, and you have to build it yourself.

Note that it still has no input or output fuses, nor any overtemperature
sensing or limiting (just like the Todd). A better design would include
these features. And it would have been waterproof if we had replaced the
Todd filter-rectifier board with Vicor's equivalent.
-- 
Lee A. Hart                  Ring the bells that still can ring
814 8th Ave. N.              Forget your perfect offering
Sartell, MN 56377 USA        There is a crack in everything
leeahart_at_earthlink.net    That's how the light gets in -- Leonard
Cohen