The Electronics Test

[JW Insider]

I don't actually know.

This is one of the surviving student teaching aids that he built. There were several designs, some with two lights and two switches, and they worked in different ways, so I can't tell you exactly how this one worked. Each of them taught something a little different but required some thinking for EE students to guess a viable solution. I spent enough time in his labs each afternoon when students came through that I wasn't told so that I wouldn't blab to to the lab assistants. 

I don't want to take this one apart for fear I'll mess it up, but some of them had two conducting wires within one side or the other of the transformer and the diode (one or two were buried in the socket for a 6v lightbulb). I remember that the bulb could be replaced but the socket had to stay. This one appears to be permanently attached to its socket, so maybe it's a different design. 

Of course, since a diode only allows electricity to "flow" in one direction, it can become a switch on its own, or remove reverse voltage spikes, etc. I see a more modern version of one of these tricks here:

 And a related discussion of the probable design here:

https://electronics.stackexchange.com/questions/23971/how-is-this-possible-3-leds-trick

The way a hidden diode is attached to a penlight or flashlight bulb creates something similar to an LED (light-emitting diode). 

If it helps, I remember he made one version where if you turned the lights way down, you could still see just a tiny bit of light when it was switched on, but 10x more light when it was off. That's actually why I took the video in a dark room to see if this was one of those, but it wasn't.

[Pudgy]

That would make me crazy, having the answer right in front of me and not taking the equipment apart to find the answer.

I still think there are no diodes, but the white wire has two conductors.  (?)

[JW Insider]

The easier one that I should have taken a picture of even though it didn't work anymore was the hanging globe.

It's just a small hollow metal globe sitting in a 3' x 4' x 4' pitch black space like a large wooden box with a rounded back, dark enough so that he poked holes in it and attached a few fake diamonds of different sizes on black wires at different  lengths to simulate a star field behind the earth.

On one side of the box there was a bright light representing sunlight but it didn't light up the back so the background still looked pitch black except for the stars. Then there was a very sensitive photocell on the other side which picked up more light if the globe tended to get pulled down (gravity). That photocell voltage was amplified to activate  a strong electromagnet capable of picking up the globe from nearly a foot no more than 6 inches away. As the magnet was strengthened by the stronger light, the globe tended to be pulled up which reduced the light and weakened the electromagnet so that it appeared to be in perfect equilibrium at all times. While designing it and tweaking it, he put a bit of black foam in front of the magnet so that it wouldn't start oscillating and smash into the magnet, which would mean painting a new globe. This could happen if you placed the globe in the air too far away from the magnet, and it got full power but couldn't stop the inertia in time to stop the globe in midair as it rose quickly to the magnet. The ability to spin it was something we didn't realize would be possible until after it was built because we thought that the magnetic field was so strong it could tend to magnetize the globe into a specific "hold" that would be difficult to spin out of.  

[JW Insider]

8 hours ago, Pudgy said:

That would make me crazy, having the answer right in front of me and not taking the equipment apart to find the answer.

I'm tempted, but I grabbed a few of his notebooks and didn't see anything yet. He also wrote articles for Popular Electronics, Nuts and Volts, etc., and I was looking to see if this was in them. All I find so far are a lot of amp and pre-amp circuit designs etc.

This just reminded me, I have an electric guitar (Mosrite/Ventures) that I once played in the District Convention orchestra, where my dad had built a simple amplifier into the case, into the small compartment along the neck for picks and extra strings. To save space he built it in "3-D" to fit into the box instead of on a larger flat circuit board, so the amp looks like an exposed mesh of wires and components attached to a 3 inch speaker, which could be mic'd at the assembly. I took it out when someone bought me a portable Marshall amp, but now I wish I had kept it as a "souvenir."

[Pudgy]

Sigh … well, I’ve thought of three ways to do it, without diodes, none involving strawberries ….

The feedback of the globe subjected to constant voltage changes to achieve equilibrium probably created torque and at 60hz bumped it up to rotational speed. Diodes would create a simulated DC  CURRENT to create the electromagnet, but it would stop and start at 60hz, possibly creating a bump effect. (?)