Paradise ponders: weird switches, doorbells, dusty sunrises, and fine wine edition... A while back, Debbie found a really pretty doorbell switch (with a brightly colored cat background). Our house has no doorbell wiring between the front door and the place we'd like a bell, so a conventional 24 VAC doorbell is impractical. Someday I'd like to build a doorbell that actually uses mechanical bells (I love the sound of them!), but for now we decided to get one of the bazillion electronic doorbells – the kind with a radio transmitter behind the doorbell switch and a receiver you plug in the wall. I figured it wouldn't be very hard to scab the pretty switch Debbie found onto the transmitter inside the plastic electronic doorbell switch enclosure.
It was harder than I expected. :) When I first wired the new switch into the transmitter, it just continuously transmitted: pushing the switch did nothing and the doorbell rang continuously. Not good. So I disconnected the pretty switch and connected it to my multimeter, which has a “beep” mode for detecting closed circuits. That did something really weird: when first connected to the switch, it made no beep (as you'd expect). When I pushed the switch, it beeped (again, as you'd expect). But then when I let go of the switch, it kept beeping – most definitely not what you'd expect. It acted as though there was some kind of active logic inside a simple SPST, NO switch. WTF? That bizzaro behavior prompted me to do a little more careful testing. With the meter in normal resistance measuring mode, I saw that the switch had 0.15 ohms resistance when pushed, but 63.5 ohms when released – not the behavior I'd expect in a simple switch! The resistance measured the same with the leads in either polarity, so it was a simple resistance, not a diode. I finally figured out that the switch had an incandescent lamp in it. I tested it at 24 VAC, and got a dim glow – perfect for spotting a doorbell in an unlit doorway at night. There was no indication on the packaging of the existence of that lamp, so it caught me completely by surprise. Fortunately the lamp was wired across the switch terminals with some barely visible wire; a couple of snips and the lamp was gone. After that, the switch worked as expected, and now we have a doorbell!
The sunrise this morning looked like it was filtered through dust, or possibly smoke. An even orange glow covered about 120° of the horizon, quite odd looking.