Potato Chip Bag Speaker

I gotta try this:

From Tim Hunkin's 2nd video (Solenoids and Relays) from the 3rd season of The Secret Life of Components:

source: https://youtu.be/fdj_g_1tj4c?t=982

It's at about 16 minutes, 22 seconds into the video.

A good excuse to buy some potato chips if nothing else :)

BTW, the weirdest relay I ever encountered (and still use every day in the heating season) is a Minivector 24 volt electric heat relay.  It would sometimes stick ON (this is bad :)

The relay isn't magnetic, instead a bimetallic plate is heated when the thermostat goes ON.  As this plate expands it presses on the actuate buttons of two C&K switches (like microswitches on steroids) to turn on the power to the baseboard heaters.  

The only reason for doing it this way that I could see was to take advantage of the built-in hysteresis of the switches.  Like a microswitch, these bigger C&K units have different actuate and release points.  It's very similar to the thermostats in a simple baseboard heater with a knob setting.  But there the knob physically positions the bimetal plate against the switch buttons.  

Best Regards,
Chuck, WB9KZY
http://wb9kzy.com/ham.htm