Steve's useful Circuits thread

[mixedgas]

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.

[mixedgas]

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

[Greg]

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.

[Greg]

What the world wouldn't have been without mica.

[mixedgas]

What the world wouldn't have been without mica.

The mica and quartz sand mines in South Carolina need to be protected with anti-missile systems, but I digress.

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.

[Greg]

When I think of Gate Driver Non Invert and Invert, like the lightly educated self trained monkey with a few gotos that I am, I think of a BJT in common collector same as emitter follower. High impedance input, lower impedance output. And for invert, a common emitter held in cutoff so the voltage on the collector is high until an input swings it into saturation and the collector goes near ground.

I've had this stuff for decades and never thought to do this experiment until last week. Maybe everyone here but me already knew this, but the triboelectric effect of shaking a mercury switch near a discharge tube containing neon stimulates the neon into emission that is visible with dark adjusted eyes. It works with the HeNe tube and the neon sign, and fluorescent tubes, but no effect appears from the other tubes containing things that are not neon. There is something in these mercury bulbs shown in the photo that produces a faint whitish discharge when the tube is shaken. Guessing argon.

[laserist]

The "triboelectric effect" - Geek Cred Gold