Gone for electrical power today, in the form of a Special Cosmotron, from July 1973. The 7803 movement in these was the last development of the 78 hybrid, electro-mechanical calibre. Running at 36,000 beat per hour, the 7803 has some additional features, indicated by a button at 8 o’clock. This feature is described, along with more info on this calibre here: https://sweep-hand.org/2013/11/28/cosmotron-7803a-movement-the-special-version/

This one has a nice one piece case, although other 7803’s have screw down backs. And as with other 78xx movements the day/date change is unusual – more on that can be found on the X8/Cosmotron page: https://sweep-hand.org/the-x8-cosmotron/

The watch is running well 🙂

SONY DSC