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From: jallen@csserv1.ic.sunysb.edu (Joseph Allen)
Newsgroups: sci.electronics
Subject: Re: How do mechanical car-radio preset pushbuttons work??
Message-ID: <1991May17.034530.21765@sbcs.sunysb.edu>
Date: 17 May 91 03:45:30 GMT
References: <9105151026.aa18960@PARIS.ICS.UCI.EDU>
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Organization: State University of New York at Stony Brook
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In article <9105151026.aa18960@PARIS.ICS.UCI.EDU> honig@calliope.ICS.UCI.EDU ("David A. Honig") writes:
>------- Blind-Carbon-Copy

>Subject: How do mechanical car-radio preset pushbuttons work??
>Date: Wed, 15 May 91 10:26:10 -0700
>From: "David A. Honig" <honig@calliope.ics.uci.edu>
>Bcc: Blind Distribution List: ;

>I can't figure it out and its driving me crazy.  Thanks.

>David
>------- End of Blind-Carbon-Copy


The tuning capacitors (or inductors; many car radios were tuned by moving a
slugs in an inductors) are attached to a shaft which runs the length of the
buttons.  This shaft has two parallel arms on it to make it into a rocker. 
I.E., if you press down on one arm, the tunning goes all the way to one and
and if you press on the other, it goes all the way to the other end. 

Each button is on the end of sliding strip of metal- when you press or pull
the button, the strip slides inward or outward.  There are two levers on each
strip.  These two levers are fixed so that they are both always at the same
angle.  One lever is in front of the tuning rocker and one is behind it.  

Normally the levers are fixed into position (by being squeezed against the
sliding strip).  When you press a button, the front lever presses against the
tuning rocker and the station is selected (by having the tuning rocker match
the angle of the lever).

When you pull the button out, the levers are allowed to move freely.  So when
the lever behind the rocker is pressed against the rocker, the angle of the
levers is changed.

This is basically how it works.  It's probably done slightly differently in
each radio.

Arn't mechanical computers neat?  There's lots of these things:

- Some things have a row of buttons, but only one is allowed to be in at
  one time.  Some even have more exotic combinations, button 1 & 2 may be
  in at the same time, but button 3 may be in only alone.  How was it done?

- How did electromechanical juke-boxes queue-up your record selections?

- How did automatic record changers work?

- How did dishwasher and washing machine controllers work?

- How did slot machines work?

- How did telephone switchers work?

- How did 8-track players with direct track accessing (a button for each
  track) work?

- How do automatic transmissions work?

- How does spark timing advance work on car engines without computers?
  (I junked my last car because the electronic version of this broke.  If it
  was mechanical I could have fixed it for very little money (and it probably
  wouldn't have broken))

- How do differentials work?

- How does power steering work?

- And, of course, how do clocks work?  Especially ones with chimes?

Anyone else can contribute to this list?  I'd like to here about other nifty
mechanical computers.  I'm sure there's lots of them.
-- 
/*  jallen@ic.sunysb.edu  */     /* Amazing */     /* Joe Allen 129.49.12.74 */
int a[1817];main(z,p,q,r){for(p=80;q+p-80;p-=2*a[p])for(z=9;z--;)q=3&(r=time(0)
+r*57)/7,q=q?q-1?q-2?1-p%79?-1:0:p%79-77?1:0:p<1659?79:0:p>158?-79:0,q?!a[p+q*2
]?a[p+=a[p+=q]=q]=q:0:0;for(;q++-1817;)printf(q%79?"%c":"%c\n"," #"[!a[q-1]]);}