Recent content by DaveE

My approach relied on symmetry and geometrical reasoning with just a tiny bit of calculus. Since these two curves are translated and inverted versions of each other, I used a shifting transform to locate the origin at the midpoint between the maximum and minimum points on each curve. Because...

I think you'll find that He is more expensive than electricity.

I wonder if you could use a diffraction grating instead of a calibration slide? The spacing will be well known and much smaller. Less than 1um should be available. https://www.edmundoptics.com/c/gratings/621/ Maybe a CD you don't like anymore, if you're cheap. They have 1.6 um tracks according...

There are both types. The eyepiece version is normally called a reticle. He's referring to a calibration slide on the stage (stage micrometer). Something like this, but better. https://www.edmundoptics.com/p/reticle-calibration-stage-micrometer-nist-traceable/16039/

Truly a classic, this one.

Yes!!! As everyone here has said, it's about the water, not the gas (although I wouldn't use Helium). Not so much. Also, remember air is 80% N2. [Post edited by a Mentor] PS (3/11/2026): https://www.applerubber.com/hot-topics-for-engineers/the-permeability-of-rubber-compounds/

Why? I'm not sure what makes a relaxation oscillator "standard", but the operating frequency isn't hard to make whatever it is. Yes, 100% agree. You'll want the inductor to be part of a high(ish) Q tank. This will help a lot with energy storage (efficiency) in the transmitter field as well as...

I would look into resonant SMPS designs. My first guess is a resonant LLC half-bridge topology, but I haven't looked into this for a few decades. There is a lot of information available and probably some control ICs. Look at TI.com and Analog.com (or google) for starters. If you're not finding...

I wonder when I read these polls how many of the small response items are people just #$@^&# with the pollsters. 4% believe in shape shifting reptilian people? Really? 1 out of every 25 people? Not in my community (I think hope). Then I wonder if the pollsters add questions like that just to...

Another entry in the "old semiconductors I found in my fathers stash" category. 2N2153, a Ge PNP power transistor in a (weird) TO-36 package. This must be from the early 1960's before TO-3 took over. This one says "Solitron" on it, which is apparently still making power transistors (but not this...

1) Let's not confuse UFOs with extraterrestrial visitors. I personally saw a UFO, just the other day. It might have been an A320, or a 737. I'm not sure. 2) I wouldn't trust a lawyer, community activist, or politician to do the analysis, as much as I might like them. 3) He said that there...

Also: - Blinking or looking away. - Turning their head away. - Bending their body (spine). - Soft muscle tension in their face (eyes, cheeks and forehead). - Mouth neutral, neither closed or showing teeth. - Relaxed, normal breathing. Not panting or holding breath. Sniffing is OK (unavoidable...

If you're interested in this, this is a really good book to check out. Plus it's short with a lot of pictures: https://www.dogwise.com/on-talking-terms-with-dogs-calming-signals-2nd-edition/?srsltid=AfmBOop-yPxrfrzMZDeeUfwG1qoQzqF7caWGyMDCaYlg-kfeYE9DBS_A I think every dog owner should read it...

This discussion reminded me of this experiment. Could it be that humans are as smart as dogs? Look they can track things with their nose!

It will be hard to select more expertise in human relations, since they are already experts. The pinnacle of domestication, they see more about our behavior than we know. Dogs know how to communicate with humans for the important stuff, but do the humans care to listen? Many obnoxious dog...