10 Dec
2000
10 Dec
'00
3:45 p.m.
-----Original Message-----
From: ajp166 <ajp166(a)bellatlantic.net>
To: Classic Computers <classiccmp(a)classiccmp.org>
Date: Sunday, December 10, 2000 9:44 PM
Subject: Re: Professors worry that engineering students don't tinker
From: Tony Duell <ard(a)p850ug1.demon.co.uk>
(regenerative
> >-tony (who grew up holding a acrewdriver,
built his first radio 28
years
>> >ago. For the UK people, the semiconductors were an OC45 >> >RF/AF stage), 2 OC71s (AF stages) and a
couple of OA81 diodes. That
>> >should identify it. And who's probably fiddled with more pieces of
>> >machinery and electronics than an entire graduating engineering
class
has
at
>at
most universities...)
You know, I am a little concerned that not one UK member of this list
recognises that radio circuit. I thought just about everybody built it some point...
Actually it's more unique to the UK than here in the usa. The common
transistor radios here were the very simple 2 transistor reflex and the
standard
six transistor superhet.
I'm likely one of the few here that has built the AA5 (all American 5) 5
tube AM superhet that was common, later transistor designs and IC
based systems. Most of my efforts were in generatiing RF power
and measuring it. the thing that keep my interest is the intersection
of communications (radio) and computers.
Building and analysing already built machines is a great exercise and
creative
instigator.
Allison
10 Dec
10 Dec
9:53 a.m.
Yup.
Five tube Heathkit AM radio followed by a 20 watt stereo amp followed
by a 25" (RCA if I remember correctly) color TV. The last one had a
BUNCH of parts and took about a month and a half of soldering to get
it all together. Taught me all, and I mean ALL, about thyristors.
Stereo taught me all about diode bridges. Each kit had their quirks
and required a steady hand, a keen eye and a BRAIN to put them
together and make them work.
My dad built a complete Dynakit component stereo in the mid sixties.
The power amp is still sought after by audiophiles (Dyna Stereo 70,
True class A amp) even though the power tubes are long NLA. After
nearly forty years it still drives those 15" Altec-Lansing VoT
speakers and sounds better than any system I've heard. Clean!
Those experiences were far better than a four year degree. Not only
did I learn how it was *supposed* to work, I was forced to learn how
it *did* work. The loss of companies like Heath (build your own pdp),
Dyna, and Knight is really an educational opportunity lost for many 'students'.
Jim
ajp166 wrote:
>Actually it's more unique to the UK than here
in the usa. The common
>transistor radios here were the very simple 2 transistor reflex and the
>standard
>six transistor superhet.
>
>I'm likely one of the few here that has built the AA5 (all American 5) 5
>tube AM superhet that was common, later transistor designs and IC
>based systems. Most of my efforts were in generatiing RF power
>and measuring it. the thing that keep my interest is the intersection
>of communications (radio) and computers.
>
>Building and analysing already built machines is a great exercise and
>creative
>instigator.
>
>Allison
>
8:42 p.m.
My dad built a complete Dynakit component stereo in the
mid sixties.
The power amp is still sought after by audiophiles (Dyna Stereo 70,
True class A amp) even though the power tubes are long NLA. After
Not class A, plain old A/B, 35 watts a channel, nothing special about the
tubes which you can still get easily, and IMHO nothing special sound
desired more for the obvious coloration and bass boost, plus its original
quality, low price.
11 Dec
11 Dec
7:28 a.m.
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10:50 a.m.
On Mon, 11 Dec 2000, Tony Duell wrote:
I've never built a complete TV :-(. But about 10
years ago we got digital
stereo TV sound over here, using a system called NICAM (Near
Instantaneous Companded Audio Multiplex IIRC). Maplin (a hobbyist
electronics shop over here) sold a NICAM tuner/decoder kit. This was
essentially the entire tuner and IF strip of a TV, and a NICAM decoder
board (using the Toshiba chipset), and the necessary tuner control
electronics, optional IR remote control, etc.
Yes, I built one, almost as soon as it was available. It wasn't
difficult, but there were a lot of parts. 80-odd ceramic capacitors on
the decoder PCB IIRC. Aligning it wasn't hard either, even using an
off-air signal
[To make this marginally on-topic, for the initial tests I tapped 12V off
the PSU in my Minc and used that to power the tuner/decoder. And viewed
the video output on a little greenscreen monitor that origianlly came
with one of my Apple ][s.]
I also built the Velleman PAL-RGB decoder. Again, it was almost a
no-brainer to put together. Worked first time IIRC.
I think that you are quite correct Tony. The story at the height of
Heathkit sales was that the assembly instructions were proofed by having
a clerk or secretary construct one. The thinking being that this would
identify any errors or ambiguities in the text. Having done so one
time, s/he was never again invited to repeat.
- don
Stereo taught me all about diode bridges. Each
kit had their quirks
and required a steady hand, a keen eye and a BRAIN to put them
together and make them work.
Odd... I find that properly designed kits don't need to much thought to
put them together -- I suspect a lot of people could assemble a Heathkit
without learning much electronics. Of course kits with 'bugs' in them are
another matter (and yes, I've had a number of those over the years..).
However, if you want to learn electronics then you can learn a lot by
assembling _any_ kit. Those
experiences were far better than a four year degree. Not only
did I learn how it was *supposed* to work, I was forced to learn how
it *did* work. The loss of companies like Heath (build your own pdp),
Dyna, and Knight is really an educational opportunity lost for many 'students'.
Yes...
As I've said before, the UK's interpretation of the EU EMC directives
doesn't help. Over here, they apply to kits as well (basically, a kit
assembled according to the instructions has to meet all the EMC standards
that a commerical product would have to meet). This has essentially
killed off the sale of kits over here. The fact that it was cheaper to
buy than build for a lot of stuff didn't help, but kits were still sold
for a lot of things until the introduction of the above directives.
Now we get the Velleman kits and not a lot else :-(
-tony
7:39 a.m.
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ajp166＠bellatlantic.net -
ard＠p850ug1.demon.co.uk -
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