tube CD player (was Re: sizes (was Re: vacuum tube computer))

From: Eric Smith <eric_at_brouhaha.com>
Date: Mon Feb 1 17:37:24 1999

Tony Duell <ard_at_p850ug1.demon.co.uk> wrote:
> Why not? There's a picture of a prototype audio or video disk player in
> an early 70's issue of 'Television' magazine that uses a HeNe laser tube

Prototype? Bah! *PRODUCTION* laser video disc players used HeNe tubes.

> What are you going to use as a photodetector? A photomultiplier tube?
> Can't have a solid-state detector, of course :-).

Well, if I resign myself to using semiconductor diodes (like most tube
computers did), I guess using a photodiode detector would be OK. On the
other hand, that same reasoning suggests that a laser diode would be OK,
but that would spoil some of the fun.

Another problem is that standard CD transport mechanisms, in addition to
using solid-state lasers and photodetectors, also use brushless DC motors
incorporating semiconductor hall-effect sensors and a control IC.

I suppose I'd build an early prototype the CD player using a standard CD
transport, but that wouldn't be suitable for the finished product.

Actually, I fully intend to build a proof-of-concept prototype that does
use semiconductors. But it will not use an standard CD chips; instead
it will be implemented entirely out of 74xx parts, standard memories, and
perhaps PLDs or FPGAs. The purpose of the proof-of-concept prototype is
that if I can't build a working CD player out of that stuff, there's no
way I can build one out of tubes.
Received on Mon Feb 01 1999 - 17:37:24 GMT

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