How?s this for a ?cold case? <https://www.tomshardware.com/pc-components/sound-cards/diy-amiga-sound-sampler-circuit-mystery-solved-32-years-later-magazine-instructions-had-key-component-spec-typos>:
an issue of ?CU Amiga? magazine from 1993 had a project to let you
build your own audio sampler -- only it never worked.
One of those hackers who tried, and failed, to follow the project at
the time recently revisited it, and delved deeper into trying to
figure out why the completed project did nothing but crash his
machine. He found a couple of errors in capacitor values, particularly
one that threw a clock frequency way off -- instead of 30kHz, it was
putting out only 287Hz.
After fixing these problems, he finally had his working sampler!
Worth noting that one of those typos was pointed out in the subsequent magazine issue, but it?s not clear that the other one was ever
corrected. Without that fix, it?s hard to see how anyone could have successfully built the project. Did all those who failed simply chalk
it up to their own (assumed) lack of ability?
Imagine all those young, budding electronics engineers who were put
off that career for life, because they couldn?t figure out how to get
this thing working ...
On 11 Nov 2025 16:59:41 +0000 (GMT), Theo wrote:
I suspect the number of people who made circuits out of computer
magazines was relatively small [I did!]. Probably more for dedicated electronics magazines which were all about publishing projects.
I think that's true for wood working, needle crafts, boat building, and so forth. It's sort of a vicarious feeling of satisfaction as people think 'Yeah, I could do that!'.
I'm just as bad. i see MCU projects in Make magazine and websites that I could do. Sometimes I even have all the components on hand but soemhow I never get roundtoit.
rbowman <bowman@montana.com> wrote:
On 11 Nov 2025 16:59:41 +0000 (GMT), Theo wrote:
I suspect the number of people who made circuits out of computer
magazines was relatively small [I did!]. Probably more for dedicated
electronics magazines which were all about publishing projects.
I think that's true for wood working, needle crafts, boat building, and so >> forth. It's sort of a vicarious feeling of satisfaction as people think
'Yeah, I could do that!'.
That and an interesting puzzle in the vein of 'C4 and R8 form a high pass filter into the base of Q3, which is biased via R7 and R9. Q5 ....'
It's nice to try to understand how a circuit works even if you'll never
build it, or have no use for the intended application.
(there were lots of projects like 'DIY electronic ignition for your car' and I do wonder how many people actually built them in order to mod their cars)
I'm just as bad. i see MCU projects in Make magazine and websites that I
could do. Sometimes I even have all the components on hand but soemhow I
never get roundtoit.
At that time I did build things just to build them, without actually having much use for the end result. I tend to be a bit more circumspect about needing something nowadays.
Theo
How?s this for a ?cold case? <https://www.tomshardware.com/pc-components/sound-cards/diy-amiga-sound-sampler-circuit-mystery-solved-32-years-later-magazine-instructions-had-key-component-spec-typos>:
an issue of ?CU Amiga? magazine from 1993 had a project to let you
build your own audio sampler -- only it never worked.
One of those hackers who tried, and failed, to follow the project at
the time recently revisited it, and delved deeper into trying to
figure out why the completed project did nothing but crash his
machine. He found a couple of errors in capacitor values, particularly
one that threw a clock frequency way off -- instead of 30kHz, it was
putting out only 287Hz.
After fixing these problems, he finally had his working sampler!
Worth noting that one of those typos was pointed out in the subsequent magazine issue, but it?s not clear that the other one was ever
corrected. Without that fix, it?s hard to see how anyone could have successfully built the project. Did all those who failed simply chalk
it up to their own (assumed) lack of ability?
Imagine all those young, budding electronics engineers who were put
off that career for life, because they couldn?t figure out how to get
this thing working ...
On 11 Nov 2025 22:08:41 +0000 (GMT), Theo wrote:
(there were lots of projects like 'DIY electronic ignition for your car'
and I do wonder how many people actually built them in order to mod
their cars)
I did :) The project specified a particular ferrite core that was unobtanium. A friend knew a guy who knew a guy... At the time IBM spun
off a lot of little cottage industries to handle stuff that they didn't
want in house, in some cases because of paranoia about being a monopoly. Anyway the guy in question was operating his little ferrite business out
of his garage. I drove down to his place in the outskirts of Kingston. As
i recall he gave me the cores as a sample to avoid paperwork. And I was on
my way to a CDI!
I've looked at enough of those projects that when I see some strange component or parts with values that aren't common I realize those were whatever the author had laying on his workbench at the time rather than
the result of careful design.
I still have a collection of ferrite toroids, air variable caps, and so
forth from when I was messing around with radios. You can bet if I design something it will be using them. Good luck finding the exact part in 2025.
Many coils and variable capacitors at the time were unobtanium :-(
Several projects I actually built did not have the exact pieces. Some
worked some not. Like one amplifier that required a couple of matched
push pull transistors. Each transistor I got was a different type of equivalent in different packaging. One plastic, the other metallic.
I wonder how many projects I made failed because of printing typos
:-/
Those BASIC programs printed in magazines that required PUSHing half
a page of hex values must have been fun. Years ago I had a TracFone
where actuation required entering 24, iirc, hex values. Great fun.
On 12 Nov 2025 18:40:09 GMT
rbowman <bowman@montana.com> wrote:
I wonder how many projects I made failed because of printing typos
:-/
Those BASIC programs printed in magazines that required PUSHing half
a page of hex values must have been fun. Years ago I had a TracFone
where actuation required entering 24, iirc, hex values. Great fun.
Compute's Gazette actually developed a checksum system for those pages
upon pages of DATA statements so's readers could catch and correct
typing errors on a line-by-line basis o_O
Carlos E.R. <robin_listas@es.invalid> wrote:
Many coils and variable capacitors at the time were unobtanium :-(
Several projects I actually built did not have the exact pieces. Some
worked some not. Like one amplifier that required a couple of matched
push pull transistors. Each transistor I got was a different type of
equivalent in different packaging. One plastic, the other metallic.
I used to avoid projects with inductors because they were much harder to get hold of than resistors or capacitors. Often the magazine would say 'we arranged with XYZ supplier to stock the Coilcraft 1234-56789' but you just knew that would be trouble, especially if it was a past issue and the supplier had probably run out. Winding your own was similarly risky - there was usually a ferrite core that was similarly unobtainable.
It was very 'cargo cult' - you need XXXX-XXXX part number inductor/core/transformer, instead of saying 'you need an inductor of XX uH that supports YY amps up to ZZ kHz' at which point you might have been able to find a replacement by specs locally.
On Wed, 12 Nov 2025 10:46:47 +0100, Carlos E.R. wrote:
I wonder how many projects I made failed because of printing typos :-/
Those BASIC programs printed in magazines that required PUSHing half a
page of hex values must have been fun. Years ago I had a TracFone where actuation required entering 24, iirc, hex values. Great fun.
In article <20251112110002.00004ddd@gmail.com>,
John Ames <commodorejohn@gmail.com> wrote:
On 12 Nov 2025 18:40:09 GMT
rbowman <bowman@montana.com> wrote:
I wonder how many projects I made failed because of printing typos
:-/
Those BASIC programs printed in magazines that required PUSHing half
a page of hex values must have been fun. Years ago I had a TracFone
where actuation required entering 24, iirc, hex values. Great fun.
Compute's Gazette actually developed a checksum system for those pages
upon pages of DATA statements so's readers could catch and correct
typing errors on a line-by-line basis o_O
Nibble had a couple of checksum systems to cover both BASIC programs and binary blobs. They sold their first one, but the second one was offered as both a paid program that would dump checksums for a program and a free version, small enough to include in every issue, that would check each line as you typed it in.
I took that free version and hacked it into something that would dump checksums for a program you'd already typed in. If I remember right, I
tried submitting that back to them as a suggested improvement, but they weren't interested for some reason. :)
Fun fact: a dump of checksums from the older of these systems shows up in
The Terminator as part of the T-800's HUD-like display:
https://www.youtube.com/watch?v=v0vbTHd04gE
I found this explanation, which tracked down the particular issues of Nibble with code featured in the movie:
https://www.theterminatorfans.com/the-terminator-vision-hud-source-code-explained/
Worth noting that one of those typos was pointed out in the subsequent magazine issue, but it?s not clear that the other one was ever
corrected. Without that fix, it?s hard to see how anyone could have successfully built the project. Did all those who failed simply chalk
it up to their own (assumed) lack of ability?
Imagine all those young, budding electronics engineers who were put
off that career for life, because they couldn?t figure out how to get
this thing working ...
Lawrence D?Oliveiro wrote:
...
Worth noting that one of those typos was pointed out in the subsequent
magazine issue, but it?s not clear that the other one was ever
corrected. Without that fix, it?s hard to see how anyone could have
successfully built the project. Did all those who failed simply chalk
it up to their own (assumed) lack of ability?
Imagine all those young, budding electronics engineers who were put
off that career for life, because they couldn?t figure out how to get
this thing working ...
amazingly i built a model railroad control system back in the
mid-to later '70s from a series of articles in a magazine and it
worked.
there were step-by-step instructions and measurements you took
at certain points to verify things worked. i had it up and
running before i went away to college but the house it was all
set up in was sold when i was away at college so i ended up with
boxes of model railroad, parts for the engines, all the electronics
and things all packed together in a rather jumbled mess. i don't
know if the guy i sold it all to ever used it and some years later
after he passed away his wife asked me to sell it for her and i
had my brother do it so i never set it all up again.
as a description is that it was a fixed voltage on the rails so
you did not need to break the circuit into different parts and the
computer imposed a signal on that voltage that was picked up by
receivers in each engine you had going. so you needed a controller
for each engine. at most i had three engines running at once but
i think the overall capacity was more than that (enough that i
doubt i'd have been able to run them all due to current limitations.
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