SBC6120 (a build-it-yourself PDP-8 clone) grammer checked

Roy J. Tellason rtellason at
Fri Jun 16 21:37:27 CDT 2006

On Friday 16 June 2006 07:53 pm, Chuck Guzis wrote:
> On 6/16/2006 at 5:00 PM woodelf wrote:
> >Since you got more books than me, Do you have anything on the
> >frequency response of 0b2 voltage regulator with the standard .01 uf
> >bi-pass cap? I was hopeing to use a few in my latest amp?
> It's not above medium audio frequencies. (a few KHz at best).
> The odd thing about gas-discharge tubes is that they work at all by sheer
> probability.
> If you can exclude all external and internal radiation (e.g. gamma
> particles, light), a neon bulb won't fire at a voltage anywhere near its
> spec-sheet level.  The ionization avalanche needs an energetic particle or
> photon to get it started.  That's why neon bulbs fire at higher voltages in
> a dark room than in a lit one.  Manufacturers put a bit of radioactive
> material (sometimes Krypton 85) in the gas mix to even things out.  Very
> old gas diodes tend to operate a bit more unpredictably than new ones
> because a fair amount of the ionizing trigger material has decayed.
> The curious upshot then, is that the time from the application of voltage
> to the full ionization of a gas diode isn't consistent.

I find those parts interesting,  anyhow.  Which is why I've got myself an OC3 
tube here,  and some neons,  to play with one of these days...

Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space,  a critter that can
be killed but can't be tamed.  --Robert A. Heinlein, "The Puppet Masters"
Information is more dangerous than cannon to a society ruled by lies. --James 
M Dakin

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