Vintage Duplex Clock Co. Time-Keeper Wood Case,Unique Electric-Mechanical Clock

Vintage Duplex Time-Keeper Wooden CaseDuplex Clock Company, of Waterbury, ConnecticutModel No. 50Movement: Ivan Trepainter Movement, invented by Ivan Trepainter There is a white spot under the 12, I am not sure what it is for, but I have a similar clock, where a red dot would appear there, alerting the owner to the need to reset the clock (by obtaining the accurate time). So if you unplug and plug back the cord, there should appear a red dot. But nothing happens here. Also, on the back of the clock is a wind-up key. Not sure what this is, it may even be for a backup mechanical system. I am not going to open the clock and find out (and have Mr. Clock spread out all over the room). That will be buyer's surprise.. Anyway, this wind-up key seems, by touch, to be fully wound-up. I will run the clock for a couple of days and see if this key starts to wind down. Otherwise the clock runs smoothly, doesn't make an irritating "hum" noise, is nicely varnished and comfortable-looking (doesn't have a hi-tech or gloomy black plastic look). Found some history of this unique timepiece, from the October, 1951 issue of Popular Mechanics (pages 14 and 16), and in the February,1952 issue of Popular Science (page 147) describes this as an Found out what this is: This clock has a wind up movement and an electrical movement combined into one.For all practical purposes it seems to have a Telechron electrical movement using a "F" rotor and coil assembly.The mechanical movement combined with the electrical movement is of unknown origin to me.Very ingenious how the clock works.Once the clock is plugged into the electrical outlet the magnetic field "freezes the balance wheel" due to the current going through the movement.On the other hand once power is interrupted the magnetic field is lost and the mechanical movement takes over never losing time. Manafacture: Duplex Clock Company Inc of Conn.Model Number: 50Movement: Trepainter movement invented by Ivan Trepainter.Patent Number: 2108931 and/or 02108931 both numbers are mentioned Patent filed on 8-7-1935President of company: Ivan Trepainter at least until 1950 according to stock cit.. Anyway, the mechanical part does not seem to work, because it is probably overwound, or stuck. The mysterious spot under the 12 would likely indicate if the clock is in mechanical or electric mode. Thanks for looking!