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The Three-way Switch

This week I am kicking it down a notch. My topic is not about global warming or our healthcare system or the upside and downside of AI. It is about the simple three-way switch of a table lamp. We have two beautiful, but old, table lamps on which neither has a properly functioning three-way switch. My wife talked to our handyman, and he said he could not repair them. She arranged for an electrician to come to the house, but he called the day before and said they don’t repair three-way switches.

When I was in my early teens, I had a wonderful electronics workbench built for me by my grandfather. I was building ham radio equipment, electronic test equipment, and even televisions, all from scratch. I said to myself, how hard could fixing a three-way switch be? Step 1: Amazon. Sure enough, they had the lamp switches for $5.99 and delivered them the next day.

The new three -way switches weighed one ounce. The broken old ones weighed five ounces. They were solid brass. No problem, I thought, because they are the same size and fully compatible. The first step was to separate the two parts of the switch so I could get at the wires. On the new switches you simply pull the two parts apart. One the solid brass switches, the two pieces were screwed together. It looked easy to just unscrew them. Yes, it looked easy but turned out to be impossible. I even deployed a pipe wrench. No way. No problem, I just chopped off the end of the wires coming from the old switches. I pulled some of the wire through the lamp to make up for the wire inside the inseparable old switches. I stripped the wires, twisted them, connected the wires to the inside of the new switches and, voila, brand new switches worked perfectly. The project got me thinking, how do three-way switches actually work?     

Three-way bulbs have two separate filaments of different wattages inside. For example, a common three-way bulb might have a 50W filament and a 100W filament. Each filament has its own electrical contact point on the bulb base. The three-way switch connects the power to different contact points on the bulb base sequentially. The first click of the switch connects the power to the 50W filament, resulting in a low-brightness light. The second click disconnects the 50W filament and connects to the 100W filament, making the light brighter. The third click disconnects the 100W filament and connects both filaments simultaneously, providing the maximum brightness of 150W (50W + 100W). The fourth click disconnects the power from both filaments, turning the light off. Like magic!

Around 2009-2010, breakthroughs in LED efficiency and dimming technology paved the way for viable three-way LED bulbs. By the mid-2010s, three-way LED bulbs became more affordable and accessible, increasing their market share. Unlike incandescent bulbs with separate filaments, LED three-way bulbs use multiple sets of LEDs arranged strategically within the bulb. These sets can have varying brightness or color temperatures, enabling different lighting levels. Similar to incandescent systems, a three-way switch connects the bulb to the power via different contacts, activating different LED sets for varying brightness. LED three-way bulbs offer a few advantages. LEDs consume significantly less energy than incandescent bulbs, even at higher brightness levels. LED bulbs boast a much longer lifespan, reducing frequent replacements, although I have not found this to be as long-lasting as advertised. Another advantage is some LED three-way bulbs offer adjustable color temperature, ranging from warm white to cool white, further customizing the ambiance.

All of this would be much more efficient and convenient if it was part of a home automation system. See Home Attitude: Everything You Need To Know To Make Your Home Smart. So much for lamps, switches, and bulbs. Next week, I will be back with a more serious and consequential subject.   

Note: I use Bard AI and other AI chatbots as my research assistants. AI can boost productivity for anyone who creates content. Sometimes I get incorrect data from AI, and when something looks suspicious, I dig deeper. Sometimes the data varies by sources where AI finds it. I take responsibility for my posts and if anyone spots an error, I will appreciate knowing it, and will correct it.