Making Light

July 28, 2022

Hey quick question, is it a normal thing to be so used to struggling to make things work right that when you try something new and it works exactly right on the first try that you feel kind of strangely sad and empty? Or is that super weird and probably really unhealthy and hey mhoye are you OK maybe you should probably talk to someone? Asking for a me.

Anyway, today I took a desk lamp whose Halogen light had burned out, whose crappy transformer always made those bulbs sputter, and whose mildly art-deco appearance I’d always liked, and swapped it out to run an LED bulb off USB power. It took about an hour’s work to replace the light with an LED, the switch with a nice heavy clicky one and now the whole thing runs off USB-C instead of wall voltage. It emits no appreciable heat, and if these calculations are to be believed, will run for decades for a few cents per year, assuming I leave it on all the time.

I hadn’t really appreciated how big a deal USB-PD voltage negotiation was until I found out that the little chips that handle that negotiation are about the size of the end of a pencil, that if you include the USB-C port you can replace basically any low-voltage transformer with something smaller than a quarter.

The magic search string, if you want to try this yourself, is “usb-pd trigger module”, and if you have a soft spot for ideas like componentized repairability and separation of concerns you’re in for a treat. In a practical sense, this means that the negotiation about what power is delivered to a device can be tiny and inexpensive, and the decision about what’s delivering that power is a separate question entirely. So if you, like me, have seen good hardware killed by bad power, there’s a whole class of problems you can put behind you.

Another way to say that is, power bricks are obsolete now; in fact, anything that doesn’t run a motor or heat up a coil won’t need wall voltage at all. It also means refurbishing old electrical stuff just got a lot cheaper and easier. That old lamp that looked great at the thrift shop or your grandmother’s basement but hasn’t worked since the Cold War and will definitely burn your house down? For a few bucks it’s good as new, running cheap and cool.

And there it is: to my significant surprise, something was cheap, easy, and worked exactly as intended on the first try.

I don’t think I’ll be able to recognize myself, if this keeps happening.


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