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On Friday 08 November 2024 05:18:23 am Donald H Locker via groups.io wrote:

And more OT - how many of us have played with blobs of mercury or just had some in a dish on the desk?

A number of years ago I worked on a rather large machine that was supposed to assemble various plastic bits, a drop or two of mercury, and a silver pellet or two, to make cartridges for dental amalgam. I was told that the initial cost of this machine was something around $160,000, and that they'd spent between $300,000 and $400,000 to try and get it working.

There were a number of fault conditions that would stop the machine so that the operator could correct things. The nature of the fault was indicated in a little box that had a bunch of lamps in it that would project some words on to a small screen. When I first powered it up, *ALL* of those lamps were lit, because the "engineers" that designed the thing had neglected to put diodes in there to protect the solid state devices that were driving the relays. I didn't understand how they could neglect doing that...

The "logic" in this thing was on a stack of circuit boards that was in the middle of the machine, silver dust and droplets of mercury all over the place. It amazes me that it worked at all. They weren't using TTL or anything like that, it was a line of parts made by Amperex that they called "norbits", and was very simple logic, like gates and time delays and such. They kinda sorta looked like chips, but *HUGE*, over an inch across and maybe close to three inches long, and they had an odd number of pins on the package so you could only put it in the board one way. I've not run across that stuff before or since then. That logic was driven by a proximity detector (to sense the level in the mercury tank), a whole bunch of lamp/photocell pairs to sense the presence of various plastic bits, silver pellets, etc., stuff was fed into it from "vibratory feeders" each of which was driven by a small variac (!), there was a magnetic amplifier in there for the main drive, a panel with something like 28 relays to provide fault indication, and I forget what all else. Oh yeah, and the "power supply" for the electronics was a big variac, and maybe 1000uF or so of filter capacitors.

It amazes me that the damn thing worked at all.

--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, ?a critter that can
be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin

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开云体育

And more OT - how many of us have played with blobs of mercury or just had some in a dish on the desk?

Donald.

On Thursday 07 November 2024 09:00:11 am wn4isx wrote:

Did you ever see Mr. Hotdog? [I think that was the name]
A plastic tray with stainless steel spikes that impaled the hotdot.
Close the lid, plug in to the AC mains and watch those suckers cook.

It worked there was some crude "safety" interlock that only interrupted one side of the AC.
I got knocked silly trying to load it barefoot on a concrete patio. I was 10 and told Mom, "I am not touching that thing again." And I didn't. Then a hot dog caught fire and it was fun for every one. I grabbed the AC cord and unplugged it and my father sat it well away from our home and we watched it burn.

When I was in 7th grade I took "electric shop" (closest I could get to electronics in that school) and one of the projects done there was a cooker that had a sheet metal frame, a square of asbestos about 6" or so, a couple of strips of sheet metal with serrated edges that were bolted to that, and a line cord. You could put one or several hot dogs in it. They also had spools of nichrome wire and some ceramic standoffs so one could make a DIY hotplate, but I was never quite clear as to how they figured out how much of that stuff to use.

One fun time I went in there and here on the bench was one of those photocell thingies like you see on top of a streetlight. I wired that up with a lamp in a socket that would shine on the unit, and plugged it in. The room lighting was dim enough that the light would come on, shine on the photocell, turn the light off, and so on, continuing with a rather slow oscillation until unplugged. The teacher tried to see if any of the other guys there could figure out what was going on. :-)

--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, ?a critter that can
be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin

On Tuesday 05 November 2024 04:07:01 pm Roy J. Tellason, Sr. wrote:

One of the first bits of stuff had to do with a course my father was taking (that I ended up finishing). ?They had a 5x7x2 metal chassis with a 35Z5 rectifier tube and a light bulb in a socket, ?line powered of course. ?One of the things you were supposed to do with it was connect the output wires to nails stuck in a potato, ?and observe the different behavior near each of the nails.

I actually ran across a video that referrences this:



The guy does the potato trick with several different voltages, with varying results...

--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, ?a critter that can
be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin

Awesome video! I've been doing kinda the same thing. Kinda ? but with really really really really old information about crystal energy. Can't simply choose to believe it or not believe. Gonna have to try it out for myself I thought. Because what other way is there to truly believe in something. I'll make my own conclusions thank you.? I'm going to subscribe and watch the entire whole thing. I like this guy lol.

Maybe you actually got some good stuff.
Motorola used Teflon coated copper wires with a steel core in some of the
transceivers.
Of course, if you are looking for the lowest resistance you do not want
that.
Bertho

Check this out:



Now I'm gonna have to check my clip leads...

Bought a couple of rolls of small wire at a dollar store a while back, they are definitely reacting to a magnet as well. Oh well, for a dollar I'm not complaining, and they're usable to some small extent.

--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, ?a critter that can
be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin

As a technology, the conversion of a C program to Verilog is
twenty or thirty years old. Still, it was new to me and I had
a great time figuring it out. :)

A write up of the C-to-Verilog process is here:


It is an easy read so you might want to start at the beginning:



The next step is to select a spreadsheet to modify to make
it into a parallel programming language.

thanks
Bob Smith

On Tuesday 05 November 2024 07:33:55 pm wn4isx wrote:

I'm not sure an electronic organ amplifier / speaker will make a decent guitar amplifier.

I expect that beyond the power supply and output tubes (plus the phase splitter, etc.) the input end of it will be heavily customized. Maybe clone a Fender or somesuch? The project is pretty low on my list, so I haven't spent a whole lot of time looking into it yet.

Rod Elliot knows a lot about guitar amps, actually he knows a lot about audio, but used to play guitar and has a section devoted to guitar amps.

I'm familiar with his stuff, have been slowly working my way through a lot of his pages, and have corresponded with him a bit.

(snip)

I suspect an amp for an electronic organ lacks the ability to handle the clipping.

That'd be determined by the input circuitry, I think, which has yet to be configured.

Before building a case, have your brother bring an electric guitar over and check the amp for clipping on an oscilloscope.

No need, I have one on hand here.

(snip)

FWIW I play an Ibanez acoustic with an Australian piezo pickup for recording. This piezo pick up is quite possibly the best pickup for a string instrument possible.



It is significantly better then a high quality studio capacitor microphone.

I have various piezo bits in among my salvaged parts. Just for the heck of it I connected one up to my scope to show my lady what her voice looked like. I was rather surprised by the sensitivity of the thing. Easy enough to put something together if I decide to go that route. These were originally in phones, I think, to generate the "ring". But they work quite well as input devices too.

I use Elixir with Polyweb coating. The guitarists out there might investigate them.

You lost me here.

Afterthought....

If your Linux machine(s) have a good FFT program, you can isolate the output of an amp with a good AF transformer and attenuator and look at the amp's output as an FFT, clipping will jump out and smack you in the face.

If I don't have such a program, I'm sure one can be had without too much trouble.

The waveforms from a guitar pickup are not nice clean sine or even quasi sine waves. At best they are a scrambled mess. [Take a look and see.]

It's been a while, but I have looked at that...

--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, ?a critter that can
be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin