[Boatanchors] Cordwood modules (was: Re: [Glowbugs] SPOTTED: GONSET G-76)

[Bry Carling]

Hmmm, I never heard them called that before. Make sit sound like they were only good for
firewood in someone's view!



On 28 Feb 2012 at 17:20, Michael A. Bittner wrote:


Besides the stacked modules used in Motorola portable radios (One with a socket for the 
1R5 converter and one with a socket for the 1U5 detector/1st audio amplifier.), perhaps you 
are referring to the "cordwood modules" used in ICBM electronics of the time. Mike, W6MAB
    ----- Original Message ----- 
    From: Brad Thompson 
    To: Brian Carling AF4K 
    Cc: boatanchors at puck.nether.net ; dcboatanchors at mailman.qth.net ; 
    tetrode at googlegroups.com ; glowbugsmailinglist at yahoogroups.com 
    Sent: Tuesday, February 28, 2012 5:02 PM
    Subject: Cordwood modules (was: Re: [Glowbugs] SPOTTED: GONSET G-76)

    On 2/28/2012 7:34 PM, Bry Carling wrote:
    > Ah "hybrid modules" - the bane of the 1970s! A lot of companies used
    > those in organs and other gadgets I serviced back then. Those secret,
    > "Giant Integrated Circuits" before the tiny DIPs on 0.1" centres were
    > invented, or in widespread use. If one died you were almost dead in the
    > water. Seems like Lowrey used them. Maybe for oscillators or keying
    > switches.
    
    Hello, Bry--
    
    Are you referring to modules that resembled stacks of very small
    Saltines (tm) with interconnecting wires running vertically along the
    edges? IIRC, Motorola used these in some of its consumer electronics--
    namely, AM BC-band portable radios.
    
    This concept was developed as "Project Tinkertoy" at NIST (nee NBS):
    
    http://www.radiomuseum.org/forum/usa_project_tinkertoy.html
    
    Motorola also marketed its printed-circuit based products as built
    using "Pla-cir" technology (there's an accent bar over the "a", making 
    it sound like the long a in 'play'). The boards were double-sided and
    not too reliable.
    
    > I worked as a test engineer for a company that used PHILBRICKS in some
    > pretty fine signal recovery equipment in the very early 1970s, and they
    > also made their own "ICs" using two pieces of PC board spaced about 1"
    > apart with vertical wires and parts in between them, to form a cube of
    > components. Tricky stuff. Once they potted those things you were left to
    > your imagination to figure out the differential amplifiers, comparators,
    > summing amplifiers and other mystery circuits inside! Give me tubes any day!
    
    That's "cordwood" packaging-- compact, rigid when potted and nearly 
    impossible to repair (before potting)if a component failed in the middle 
    of the stack. You'd have to remove good components to reach the
    failure.
    
    One ad slogan of the times stated that "Our modules are potted in
    Timonium"-- meaning the assembly plant was located in Timonium, MD.
    The first time that I saw the ad, I wondered what kind of everlasting
    epoxy they used.<g>
    
    One thing about epoxy potting-- it covered up a multitude of of
    construction flaws.
    
    73--
    
    Brad AA1IP
    
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