(ET) Controllers

["Robert" <euclid delhitel net>]

CZ,
I fix old watches too, a Hamilton 992B anyone? Computers from the 80's, how 
about an HP71B, I still have one and use it along with lots of programmable 
HP RPN calculators like the mid 80's  11C (which is still going strong in my 
machine shop). I think it's not that those old computers broke, it's that 
they got obsoleted by software and newer technology. There are guys still 
looking for old stuff, I built a Sinclair in the late 70's that I later 
sold, nothing wrong with it, just outdated.

You have to remember when the ET was designed, the electronics was cutting 
edge, if they built it today it would have a computerized controller just 
like the new stuff coming out now, probably Li-Ion batts too. The original 
charger in the ET's is really dog eared by today's standards and a poor 
charging system overall. I'm designing a whole new system using AGM's now 
along with a new controller.

As for reversing the field, think about it, how were they going to reverse 
the field back then? With an 'H' bridge circuit, not then they weren't. The 
relay was the easiest and probably most reliable solution.

Rob

-----Original Message----- 
From: elec-trak-request cosmos phy tufts edu
Sent: Saturday, June 14, 2014 12:00 PM
To: elec-trak cosmos phy tufts edu
Subject: Elec-trak Digest, Vol 12, Issue 78

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Today's Topics:

  1. Re:  Controllers (CZ Unit)


----------------------------------------------------------------------

Message: 1
Date: Sat, 14 Jun 2014 11:09:22 -0400
From: CZ Unit <cz alembic crystel com>
To: "elec-trak cosmos phy tufts edu" <elec-trak cosmos phy tufts edu>
Subject: Re: (ET) Controllers
Message-ID: <539C65A2 2010007 alembic crystel com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

On 6/14/2014 10:57 AM, Jeff Antonucci wrote:
> Reminds me of a guy I met years ago who said he would not buy a car
> built after the intro of transistorized ignition.  Transistorized
> ignition became popular in 73 with GM's HEI.  Now there is a true Luddite.

The trick is it's possible to build really crummy electronics just as
it's possible to build really good mechanical controls. I fix pocket
watches from the 1870's, they run fine. However it is a mistake to
assume *all* pocket watches from 1870 run fine; there were millions of
junky "dollar watches" along with the good ones. The only thing that
survives is the good stuff, doesn't mean everything was good.

Same with electronics: Lots of controllers were garbage. Some were
really good. It's hard to find a running 70's vintage computer, how many
computers from the 80's are around?

The Elec-trak first generation tractors had an expensive and high
quality contactor system. Reversing the armature with interlinked
contactors allowed for 30-40 years of operation, and when they have
problems you just flip the contactors (putting reverse on the worn
connections, and getting another 40 years of use). No problem.

The second generation E15 used electronic controls for delays,
interlocks and the like and have some more reliability problems. However
the main cheapening error was putting in that stupid relay to reverse
the field. They had to build a whole system to do voltage sampling on
the field to try and ensure it didn't burn the relay. And that sort of
works, but still blows up.

Such is life. You can build a very good electronics controller that can
last 30-40 years, but it's expensive and hard to do. Easier to build
with high quality mechanical contactors, but also a lot more expensive
and harder to mass produce.

C





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