Path: utzoo!attcan!uunet!lll-winken!ames!hc!pprg.unm.edu!unmvax!tut.cis.ohio-state.edu!osu-cis!att!ihlpl!knudsen
From: knudsen@ihlpl.ATT.COM (Knudsen)
Newsgroups: sci.electronics
Subject: Re: Finding an electrically-controlled valve?
Summary: Mechanical Air Vacuum DAC
Keywords: valves, plumbing, motorized valves
Message-ID: <8486@ihlpl.ATT.COM>
Date: 16 Jan 89 21:44:50 GMT
References: <1404@accelerator.eng.ohio-state.edu> <2925@kitty.UUCP> <1235@ncar.ucar.edu>
Organization: AT&T Bell Laboratories - Naperville, Illinois
Lines: 19

[Water DAC with 4 valves bit-weighted by powers of 2].

Neat idea.  I just happen to own a pair of what must be the
oldest type of DAC in existence.
These are also 4-bitters:  4 square, flat air bellows stacked
one atop the other, with adjustable gaps of 1, 2, 4, and 8
16ths of an inch.  One end of the bellows stack is fixed
and the other output end thus takes positions of 0 thru 15
16ths of an inch in 1/16" steps.

This is part of a Duo-Art reproducing player piano, and is used
to control the vacuum level, hence piano volume, of the playback.
The output rods drive big bellows-type vacuum regulators.
Need binary D/A system, invented in 1913!  More fun to watch than
a CD player, you bet.
-- 
Mike Knudsen  Bell Labs(AT&T)   att!ihlpl!knudsen
"Lawyers are like nuclear bombs and PClones.  Nobody likes them,
but the other guy's got one, so I better get one too."