Power my old clock
January 16, 2018 8:09 AM Subscribe
How can I get this old GE clock working with a battery? It obviously used to use a wall plug, but the wire has been cut off. I tried attaching it to a single AA holder, but it didn't work. Images here: https://imgur.com/a/IjZuB. Thanks!
That looks like a continuous sweep General Electric wall clock (c. 1960s?), designed to run on mains power. Since you tried to run it on a single AA battery, I'm concerned that safely replacing the plug may be out of your comfort zone. Please be careful if you attempt this.
posted by zamboni at 8:33 AM on January 16, 2018 [15 favorites]
posted by zamboni at 8:33 AM on January 16, 2018 [15 favorites]
Best answer: If it was plugged into a wall, it was running on 120 volts of alternating current. (Not 120 hz. In Canada and the U.S., the electricity is typically 60 hertz.)
An AA battery is 1.5 volts of direct current. In fact, all batteries are DC. You can't run this clock on DC power without a transformer, and that's way more involved than you probably want to get.
Go to a hardware store and buy a new plug and attach it to the existing wires. It's not that hard, but have someone at the hardware store tell you how to do it, or look at one of the many online tutorials. (like this one)
posted by Longtime Listener at 8:42 AM on January 16, 2018 [1 favorite]
An AA battery is 1.5 volts of direct current. In fact, all batteries are DC. You can't run this clock on DC power without a transformer, and that's way more involved than you probably want to get.
Go to a hardware store and buy a new plug and attach it to the existing wires. It's not that hard, but have someone at the hardware store tell you how to do it, or look at one of the many online tutorials. (like this one)
posted by Longtime Listener at 8:42 AM on January 16, 2018 [1 favorite]
Or, if you're in love with the clock face but want something that'll run on batteries, find a battery powered mechanism that has similar hands (you might even be able to re-use the hands with some creative filing) and replace the mechanism. Hot glue is fantastic for making new mechanisms fit in old face plates.
posted by straw at 8:51 AM on January 16, 2018 [3 favorites]
posted by straw at 8:51 AM on January 16, 2018 [3 favorites]
That looks like an old classroom clock, and some of those were networked together; you can see from the different colors on the power cord that it probably passed into a wall right after coming out of the clock and might not have ever had a traditional plug that fits into a socket.
I don't think that necessarily precludes putting one on and just plugging it in, but if it was networked, I don't know how that would affect its operation.
posted by jamjam at 9:03 AM on January 16, 2018
I don't think that necessarily precludes putting one on and just plugging it in, but if it was networked, I don't know how that would affect its operation.
posted by jamjam at 9:03 AM on January 16, 2018
That looks like an old classroom clock, and some of those were networked together; you can see from the different colors on the power cord that it probably passed into a wall right after coming out of the clock and might not have ever had a traditional plug that fits into a socket.
The idea of it being a secondary clock controlled by a primary is interesting. transient, what does it say on the label on the back of the clock? It looks a lot like a GE Model 2012.
posted by zamboni at 9:23 AM on January 16, 2018 [1 favorite]
The idea of it being a secondary clock controlled by a primary is interesting. transient, what does it say on the label on the back of the clock? It looks a lot like a GE Model 2012.
posted by zamboni at 9:23 AM on January 16, 2018 [1 favorite]
If you want to get this clock working with a battery, you are going to have to replace the "movement" in the clock (i.e. the motor that drives the hands). It's the round white box on the back of the clock. Although I wasn't able to find anything for this specific clock, there are several different examples of people out there doing this: here's one and here's another. You can find more by googling "clock battery conversion." I'm sure you can find kits to do this conversion on Amazon, but a specialty store like Kockit might give you more options.
posted by Betelgeuse at 9:24 AM on January 16, 2018 [1 favorite]
posted by Betelgeuse at 9:24 AM on January 16, 2018 [1 favorite]
Best answer: Not to be flippant, but Yes, you can run this on a battery but you'll also need an inverter. It would be a ridiculous solution to a simple problem but you could conceivably use a 12v car or motorcycle battery and an inverter like this to run the clock (but you'll still need a plug on the end!). The battery is going to die relatively quickly because you'll be running a 120v motor continuously, but it can be done. Better solution of you don't have access to 120v mains would be to replace the timing guts with this.
Best solution, as mentioned, if you have access to plug the thing in, is graft on one of these.
Me? I would buy an inexpensive 16/2 extension cord of the length that gets you to the plug you want to use, cut off the female end, and graft the remainder to the clock.
Since this has a method for adjusting the time (the knob sticking out the bottom) I doubt it's set for central control (networked).
posted by achrise at 9:28 AM on January 16, 2018 [2 favorites]
Best solution, as mentioned, if you have access to plug the thing in, is graft on one of these.
Me? I would buy an inexpensive 16/2 extension cord of the length that gets you to the plug you want to use, cut off the female end, and graft the remainder to the clock.
Since this has a method for adjusting the time (the knob sticking out the bottom) I doubt it's set for central control (networked).
posted by achrise at 9:28 AM on January 16, 2018 [2 favorites]
Best answer: You should keep this clock and try to revive it. It is a part of history. You should be able to just put a plug on the end and it will work. In some cases, the motor might be slightly noisy because the lubricant has dried out, but this can be fixed by drop of light machine oil.
These clocks go back a century to 1917 when Henry Warren patented the use of a synchronous motor to drive a clock synchronized to the power grid. The clock company was called Telechron of which General Electric was a partner and eventually the General Electric name took over in 1943.
These clocks are among the most accurate ever made for long term timekeeping. More accurate than an expensive chronometer or digital quartz watch. This is because the operators of the electrical grid manually put in a Time Error Correction to adjust the frequency of the power grid so that it is never more than +/- 10 seconds from actual time. If your clock remains powered, it will always be within 10 seconds of correct time after 1 year, 5 years, 10 years or decades. This is unlike digital clocks that continuously drift so that the longer they run, the farther they deviate from correct time, typically a few seconds a month, a minute or two a year.
FERC has recently been trying to repeal the Time Error Correction feature of the grid saying it is obsolete, but so far there has been resistance to the change.
posted by JackFlash at 10:40 AM on January 16, 2018 [11 favorites]
These clocks go back a century to 1917 when Henry Warren patented the use of a synchronous motor to drive a clock synchronized to the power grid. The clock company was called Telechron of which General Electric was a partner and eventually the General Electric name took over in 1943.
These clocks are among the most accurate ever made for long term timekeeping. More accurate than an expensive chronometer or digital quartz watch. This is because the operators of the electrical grid manually put in a Time Error Correction to adjust the frequency of the power grid so that it is never more than +/- 10 seconds from actual time. If your clock remains powered, it will always be within 10 seconds of correct time after 1 year, 5 years, 10 years or decades. This is unlike digital clocks that continuously drift so that the longer they run, the farther they deviate from correct time, typically a few seconds a month, a minute or two a year.
FERC has recently been trying to repeal the Time Error Correction feature of the grid saying it is obsolete, but so far there has been resistance to the change.
posted by JackFlash at 10:40 AM on January 16, 2018 [11 favorites]
Best answer: As everyone else has said, that motor expects alternating current, and it would take you five minutes and < $10 to re-wire it with a borrowed wire stripper, a couple wire nuts, and a lamp cord, whereas running it from a battery will cost you at least $30 for the inverter (which is going to be big and clunky), + batteries, + still having to do some wiring.
Read this - pretty much all the same things apply.
posted by aspersioncast at 1:31 PM on January 16, 2018 [1 favorite]
Read this - pretty much all the same things apply.
posted by aspersioncast at 1:31 PM on January 16, 2018 [1 favorite]
Best answer: The inverter idea is the Wrong Thing, not only because it's massively expensive and massively inefficient, but because the frequency of the AC supply that comes out of a typical inverter is going to be nowhere near accurate enough to achieve the primary purpose of the device you're powering from it.
posted by flabdablet at 5:41 PM on January 16, 2018
posted by flabdablet at 5:41 PM on January 16, 2018
Best answer: It just needs a normal plug put on it. Just be sure that whatever you splice the cord with is strain relieved so the wire nuts or crimps aren't taking the tension load in the cord.
posted by Dr. Twist at 6:27 PM on January 16, 2018 [1 favorite]
posted by Dr. Twist at 6:27 PM on January 16, 2018 [1 favorite]
Best answer: Well, if you used a battery powered inverter the clock would be as accurate as the crystal oscillator inside the inverter from which the output 60 Hz is derived. It would be about as accurate as the typical digital watch using a crystal oscillator, which means it would drift farther and farther over long periods.
But, of course, using an inverter would be silly since you can fix this clock but putting a one-dollar plug on the end of the wire. Then it will always be accurate within a few seconds.
posted by JackFlash at 6:28 PM on January 16, 2018
But, of course, using an inverter would be silly since you can fix this clock but putting a one-dollar plug on the end of the wire. Then it will always be accurate within a few seconds.
posted by JackFlash at 6:28 PM on January 16, 2018
Response by poster: at, the model# is 2012, 120v, 60Hz. Sounds like I should just take the advice to put a cord on it and plug it in. I thought it would be nice to have it be on a battery, but just putting on a plug sounds like less trouble than getting a new mechanism or installing an inverter (the whole thing behind the battery idea was for ease and portability). But it sounds like I’m bound for the plug, which is fine.
posted by transient at 6:39 PM on January 16, 2018
posted by transient at 6:39 PM on January 16, 2018
Response by poster: And jamjam, this clock did come from an old classroom; no idea if it was centrally controlled or not.
posted by transient at 6:46 PM on January 16, 2018
posted by transient at 6:46 PM on January 16, 2018
if you used a battery powered inverter the clock would be as accurate as the crystal oscillator inside the inverter from which the output 60 Hz is derived.
I think the assumption that an inverter is necessarily going to contain a crystal oscillator and timing divider is pretty optimistic. The majority of inverters are based on dirt-cheap RC oscillators and these yield timing accurate to with a few percent at best.
Even 1% of timing error - which is pretty bloody tight for an RC oscillator - will drift a clock by 15 minutes per day.
this clock did come from an old classroom; no idea if it was centrally controlled or not.
Looks like a GE Model 2012, though the second hand is shorter than typical. I don't believe GE made master/slave clock systems, but it would be worth getting a good photo of the label on the back just to be sure. Plugging a slave clock into the mains will not end well.
posted by flabdablet at 7:35 PM on January 16, 2018
I think the assumption that an inverter is necessarily going to contain a crystal oscillator and timing divider is pretty optimistic. The majority of inverters are based on dirt-cheap RC oscillators and these yield timing accurate to with a few percent at best.
Even 1% of timing error - which is pretty bloody tight for an RC oscillator - will drift a clock by 15 minutes per day.
this clock did come from an old classroom; no idea if it was centrally controlled or not.
Looks like a GE Model 2012, though the second hand is shorter than typical. I don't believe GE made master/slave clock systems, but it would be worth getting a good photo of the label on the back just to be sure. Plugging a slave clock into the mains will not end well.
posted by flabdablet at 7:35 PM on January 16, 2018
After you put a new plug on the clock, you might want to install a recessed outlet like this or this. The second even has a hook for hanging the clock.
posted by Marky at 2:06 AM on January 17, 2018
posted by Marky at 2:06 AM on January 17, 2018
Response by poster: Plug on, plugged in, and working fine. Nothing exploded.
posted by transient at 3:35 AM on January 17, 2018 [1 favorite]
posted by transient at 3:35 AM on January 17, 2018 [1 favorite]
I would strongly recommend using something other than electrical tape to insulate those connections and strain relieve the joint. The adhesive on electrical tape has a nasty habit of soaking up atmospheric moisture, going soft and gooey and falling off.
As an absolute minimum, wire nuts on the joints and a couple of zip ties forming a two-link plastic chain off the bottom of that wall hanging bracket, with two more zip ties attaching the new cable to the bottom link, at least two cable inches away from the wire nuts. Minimum. And I'd still be expecting to get electrocuted whenever I adjusted the time.
Seriously. I'm shuddering at that tape job. You can get away with that for car speakers, but not for mains electricity.
posted by flabdablet at 4:39 AM on January 17, 2018 [5 favorites]
As an absolute minimum, wire nuts on the joints and a couple of zip ties forming a two-link plastic chain off the bottom of that wall hanging bracket, with two more zip ties attaching the new cable to the bottom link, at least two cable inches away from the wire nuts. Minimum. And I'd still be expecting to get electrocuted whenever I adjusted the time.
Seriously. I'm shuddering at that tape job. You can get away with that for car speakers, but not for mains electricity.
posted by flabdablet at 4:39 AM on January 17, 2018 [5 favorites]
Best answer: Seconding flabdablet on the electrical tape: Normally if you use wire nuts you'd put that connection inside an electrical box. I'm not sure there's a right way to splice the cord, pretty sure the proper way would be to remake the connection inside the box, but if you're going to splice the cord I'd get some really good crimp style butt connectors and some heat shrink tubing to go over those.
And an auto parts store is a good source for those.
posted by straw at 9:33 AM on January 17, 2018 [1 favorite]
And an auto parts store is a good source for those.
posted by straw at 9:33 AM on January 17, 2018 [1 favorite]
Best answer: I'm not sure there's a right way to splice the cord
If I have to splice figure-8 cord carrying mains voltage, I splice each wire with a Western Union splice, soldered, covered with two layers of heat-shrink tubing each, and offset thus
=========#####===================
===================#####=========
so the splices don't end up next to each other and make a huge lump.
Another layer of heat shrink tubing over the entire spliced region holds things together nicely and tidies it up. If the wires are cut accurately enough that the result doesn't want to curve to one side or the other (small adjustments after splicing but before soldering can help with this) and the soldering is done well, then the resulting joint is robust enough not to require strain relief. If the cable will be exposed to weather, injecting neutral cure silicone sealant into the outer heat shrink tube before shrinking it makes for a waterproof joint.
I would never ever ever rely on electrical tape instead of heat shrink tubing for a joint of this kind. I've seen it done. I've also seen it fail, nastily, often enough to give me pause. Even the rather anaemic half-strength electricity you folks in the States use merits more respect than that.
posted by flabdablet at 6:03 PM on January 17, 2018 [1 favorite]
If I have to splice figure-8 cord carrying mains voltage, I splice each wire with a Western Union splice, soldered, covered with two layers of heat-shrink tubing each, and offset thus
=========#####===================
===================#####=========
so the splices don't end up next to each other and make a huge lump.
Another layer of heat shrink tubing over the entire spliced region holds things together nicely and tidies it up. If the wires are cut accurately enough that the result doesn't want to curve to one side or the other (small adjustments after splicing but before soldering can help with this) and the soldering is done well, then the resulting joint is robust enough not to require strain relief. If the cable will be exposed to weather, injecting neutral cure silicone sealant into the outer heat shrink tube before shrinking it makes for a waterproof joint.
I would never ever ever rely on electrical tape instead of heat shrink tubing for a joint of this kind. I've seen it done. I've also seen it fail, nastily, often enough to give me pause. Even the rather anaemic half-strength electricity you folks in the States use merits more respect than that.
posted by flabdablet at 6:03 PM on January 17, 2018 [1 favorite]
Response by poster: Ok, you guys have sufficiently shamed my tape :). Unplugged for now, back to the hardware store.
posted by transient at 4:25 AM on January 18, 2018 [2 favorites]
posted by transient at 4:25 AM on January 18, 2018 [2 favorites]
Best answer: You've got plenty of space in that clock -- I'd buy a two prong plug with screw down contacts and mount it directly to the wires coming out of the motor module, and a cheap extension cord with a molded on head, plug the plug into that extension cord, and hide the whole thing in the space behind the face and below the motor module, with the head of the extension cord acting as a kind of strain relief at the opening where the wires come out of the clock.
posted by jamjam at 3:11 PM on January 18, 2018 [2 favorites]
posted by jamjam at 3:11 PM on January 18, 2018 [2 favorites]
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