Creaky Old Award Winning Bastard Technologist
Steve's useful Circuits thread
Post one, Classic Prudehomme LM555 Sweep ramp Generator for analog images There was a time when only expensive scopes had triggered sweep. Apply audio or signal generator to say Y axis, clipped to 5V for safety, apply sweep to X axis... Crude, Rude, Laser Scope. You'll need a trigger, and an optocoupler running off the 60 Hz line is fine for this.
Qui habet Christos, habet Vitam!
I should have rented the space under my name for advertising.
When I still could have...
Creaky Old Award Winning Bastard Technologist
Post two
J Gerard Anderson's "An Electronic Spirograph"
His "Christmas Tree" is included as well.
When I was a kid I biked to two university libraries and an industrial library, snuck in as a well dressed kid with a dress shirt and a bit of grease on my chinos.
Only thing I could find across seven libraries, BI, Before Internet, on how to make those abstracts I saw on the dome. Ivan's chums were not so talkative back then...
From February, 1974, The Physics Teacher.. posted under educational use clause.
If you want more info on the math and patterns, find this book:
Harmonograph: A Visual Guide to the Mathematics of Music
Note for newbies, this is method is pure tedium to adjust, we don't do anything with this style of hardware in real time.
Steve
Last edited by mixedgas; 02-28-2026 at 07:31.
Qui habet Christos, habet Vitam!
I should have rented the space under my name for advertising.
When I still could have...
Senior Member
For some time I've wanted Yuletide cycloidery to be a thing. Nice to know I'm not the first.
Hey Steve. I enjoyed that history of analog multipliers you gave us a while back. I'm reading a paper by Cockcroft and Walton about how they first disintegrated elements with high velocity protons. Particle physics could be so much fun and just within reach of the small laboratory back then. They mention something like a tape based data recorder that they call "recording keys" that apparently made a lot of noise. I haven't found out what that is yet.
Senior Member
What the world wouldn't have been without mica.
Creaky Old Award Winning Bastard Technologist
The mica and quartz sand mines in South Carolina need to be protected with anti-missile systems, but I digress.Originally Posted by Greg
Attached is today's interesting circuit, using LM or NE 555 as Base, Gate or Cable Drivers.
The sub 200 nS switching time is respectable when driving a large gate capacitance,
Makes a nice Schmidt trigger or LED driver as well.
Qui habet Christos, habet Vitam!
I should have rented the space under my name for advertising.
When I still could have...
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