Pulling -12VDC from thin air (was Re: MicroVAX II)

From: Ethan Dicks <erd_6502_at_yahoo.com>
Date: Fri Dec 13 04:23:01 2002

--- Jochen Kunz <jkunz_at_unixag-kl.fh-kl.de> wrote:
> I second that. I know a collector who knows nothing about hardware and
> how it works.... When I told him that I builded a simple voltage
> inverter (charge pump) to make the RS232 work on the Sun 4/600 MP he
> looked like it was black magic to convert +12V to -12V. (The Sun 4/600
> MP boards needs -12V for the RS232, even -5V are not enough. As I
> mounted this board in a Sun 3/60 case that doesn't provide -12V, I could
> not use a serial console.)

Interesting to learn about the 4/600 board and the 3/60 case. Long ago,
I wondered if the two could work together (I _have_ the 3/60 and I almost
had the 4/600 board).

If you'd have known to ask, I could have provided you with a +5VDC to
-12VDC converter module. It's about 20mm x 30mm x 3mm. We had to put
them on the Qbus COMBOARD because the original design assumed you could
pull -12VDC off some Qbus pin somewhere, and I suspect that it is not
the case for all Qbus enclosures (don't know where it is available and
where it isn't). I have several new on the anti-static mat they shipped


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Received on Fri Dec 13 2002 - 04:23:01 GMT

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