AC or DC? I don’t always know which is best.

It’s kind of a problem for me that you can buy AC and DC lightbulbs with the same socket size and design. Often Chinese-made, they sometimes don’t even have identifying markings which means if you store them carelessly – and of course how could that ever be a problem around here – bad things can happen. Screw a bulb meant for 120 volts into a DC12 socket and it just won’t work. Reverse the process and after a very brief popping noise the bulb will never work again. But all of that can be avoided with the use of a marking pen and separate storage spaces. There’s one application that has perplexed and annoyed me for months…


For personal reasons, this happens to be my favorite lamp. There’s nothing special about it but it’s the single possession I’ve managed to keep with me literally since high school. I got a gas money gig doing yard work and hauling trash for a little old lady – we’ll pause in a moment of silence for the dignity of my lifetime career arc – and among boxes of other stuff she was throwing away this really cool (I thought, and kind of still do) old brass lamp with nothing wrong with it except it needed re-wiring. Even oafish late-teenage me could re-wire a lamp without danger.

So I kept it. It stayed with Big Brother – who happened to need a bedside lamp, which I didn’t – for a year or two until I left the state. And somehow, through more moves than I could remember if I cared to try and after literally abandoning much baggage on numerous occasions when my life situation became unsuited to owning more than a car’s trunk full of possessions, this thing stuck with me. I’ve inadvertently crushed a lot of lampshades, but never quite managed to lose the lamp. And at this late stage of my life, I guess that makes it special.

It only just this moment struck me that there’s a certain irony to one of my favorite personal possessions being my earliest recorded scrounging score. I like to think I’ve grown since my teens – but maybe not so much.

Anyway – all of the above is a digression I didn’t sit down intending to write. What I meant to write is that some five years ago I re-wired the lamp for use directly connected to the Lair’s retrofitted 12-volt DC circuit. It was an effort to save a little battery juice and also keep a lamp useful in that corner of the cabin on occasions when the inverter wasn’t available.

And it worked fine in that capacity until a few months ago when the bulb started flickering annoyingly. I brought a replacement out of storage – and it didn’t work at all. I tried another bulb – nothing. I screwed one of those new-but-apparently-faulty bulbs into one of the bedroom sockets – worked fine.

Huh. Now I had a mystery. Maybe it was just that the lamp’s socket was old and not making contact? I replaced the socket. Nothing.

I still assumed the problem was these Chinese LED bulbs. BB recently sent me a new supply of 12-volt DC LED bulbs. I tried one of those. Nope. They simply didn’t work in the lion lamp, though they worked fine in the bedroom lighting.

It’s still a mystery – I never did figure it out. But whatever – I needed that lamp to work, it’s right over my desk. So yesterday I sacrificed a light-duty extension cord and re-wired it for AC. Screwed in a bog-normal hardware store LED bulb. Plugged it in.


With improvements in the Lair’s electrical system the question isn’t as relevant as it used to be but after all these years I’m hardwired to ask it: What was the effect on the power draw?



Basically a rounding error. The battery bank is still smaller than standard but no longer a running joke.

So after something like five years my (antique?*) lamp has gone back to being something you can just plug in anywhere.

——
*I got to wondering about this in an idle moment and looked up the definition. And it seems the answer is no. Vintage, certainly, though not in original condition. But probably a few decades from antique.

About Joel

You shouldn't ask these questions of a paranoid recluse, you know.
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5 Responses to AC or DC? I don’t always know which is best.

  1. Bear says:

    I ran into a similar issue many years ago in Turkey. Our supply guy ordered a batch of light bulbs, which were sorely needed. I started replacing burned out bulbs… and they all ran very dim when I flipped the switch. Looked a little closer, and discovered he’d ordered 220/230V bulbs. Same base/socket. Our site was US 120V.

    On the… um, bright side, those bulbs were never going to burn out.

  2. Ben says:

    In the course of our lives we churn through literally tons of possessions. Hanging on to it all would result in us being buried under a pile of useless junk! So it’s really odd to consider the bits that somehow manage to follow us through our lives. Somewhere I still have my high school gym shorts. Since I was a tubby teen, I can even claim that they fit!

  3. Zelda says:

    So Joel if you ever decide to try the 12V again and it works will you follow up with the solution. Thanks

  4. Paul B says:

    Looks like some lions clubs bric a brac

  5. terrapod says:

    Hey Joel, Engineer Terrapod here. What is likely is that right where the cord goes into the base, it has flexed enough over time from moves here and there, to break a few of the copper strands over time. When you get down to just a few intact, turn on the lamp at 12VDC, it draws enough current to melt the remaining ones and poof, no workee.

    The new cord fixed the problem. Toss the old cord before you put it into your spares bin, it saves future aggravation.

    If you want a few new cords, I just bought a dozen to fix old lamps around the house and can spare a couple.

    As to lamps, when I arrived in this country 50 years ago, I rented a room at the local Y for a few days before getting to campus. First purchase was a 3 dollar gooseneck lamp from goodwill and two cans of Testors spray paint to make it pretty. That lamp is still with me, so I fully grok your situation..

To the stake with the heretic!