Electric clocks are wonderful from an operational standpoint. But, they come with a string attached - the electric cord, specifically. As post-war society became more affluent and design conscious, that cord trailing down the wall seemed old-fashioned and unsightly. Kitchen clocks had ways to hide the cord and discreetly plug it in to a special recessed outlet. Upper-end clocks like the George Nelson designs could be wired directly into the wall. That left a void to fill for the mass market buyer, who wanted a special clock for a special focal point in their home - without the distracting cord.
Keywound clocks enjoyed some resurgence in midcentury designs, but these were old-fashioned and not quite satisfying to the modern home decorator. The shift to battery movements came suddenly - one model would be electric or keywound; a few months later the same clock would have a battery operated movement sometimes with a hole in the faceplate where a key would have gone previously. These made possible the gorgeous midcentury clocks like the Elgin starburst in the lead photo.
The Elgin has a German Voltra self-winding movement, powered by a D-cell battery. This hybrid is a small mechanical movement regulated by a hairspring balance wheel and powered by a small spring. The spring only supplies about ten minutes worth of power, so the clock also has a small electric motor. When the spring winds down it activates a switch so that power from the battery will go to the motor and rewind the spring. It may seem convoluted but I really like these Voltra movements a lot.
Here are a couple of internal views of a similar movement, the Electro by Diehl for General Electric:
The next stage of hybrid was to add electronics, usually one transistor, capacitor and resistor. I don't know what to do with electronics except hope that they work. Here is a hybrid movement from an Ingraham Vogue wall clock, which went directly from electric to a transistor hybrid:
Westclox introduced their transistor hybrids as "Isotronic" movements. Very modern and futuristic sounding, yes? Here is one of their first, along with the merchandising flyer that explains how it works:
They describe it as a "time-tested" conventional mechanical clock movement, with a magnetic balance wheel, conventional calibration (fast-slow) to the balance wheel, and a transistor to act as a switch to convert the battery current to an alternating pulse current. They were proud of this movement and even let it have one jewel. It is advertised as stopping battery leakage, although I'm not sure how that works. Battery leakage was the leading cause of death for hybrid movements. A dead battery left in the clock would leak and corrode the movement case as well as some very fine and expensive walnut and brass clock cases.
I tried to repair one of these Westclox movements from a Journal model calendar clock. Here are some views:
The transistor wasn't getting power to the movement. I took the little circuit board out, but like I said, I don't know what to do with electronics. Too old fashioned, I guess. I passed it off to someone who knew how to fix it.
I think the hybrids are great but they were short lived. Quartz movements caused their rapid demise. The thing about quartz is that the structure of the crystal itself provides complete timing accuracy. No mess, no fuss. That said, quartz is boring. The movements are all pretty much the same, and meant to be disposable and interchangeable. All the clock hands are like that too, not like the great designs where the hands were specific to the clock. Not a fan.
Notes on hybrid movements:
- Number one rule: Never Leave a Dead Battery in the Clock. It will leak acid and make a terrible and destructive mess. I have cleaned up several of them.
- Noise: These are essentially mechanical movements and they make the familiar ticking sound, although it is generally faint. The self-winding movements make a motor whirring noise about every ten minutes, which can be disconcerting until you get used to it.
- Maintenance: The mechanical parts have the same maintenance requirements as mechanical movements, i.e. periodic cleaning and appropriate (usually sparing) lubrication. The electrical contacts may need to be cleaned with contact cleaner, and the battery terminals may need special attention. If the electronics need help, don't ask me.
- These are wonderful movements. If your clock has one, please give it a chance. Dont rush to convert to quartz - please. If you do convert, send the old movement to me.