Citizen Cosmotron 7804 Electronic Balance Mid 1970s

This is a Citizen Cosmotron watch from the 1970s, the era of brightly coloured dials!
The Cosmotron is a mostly mechanical movement but powered by a battery. These were out at the same time as the very first quartz watches.  The movement in this one is a 7804. It is a mechanical movement with a balance wheel but instead of a mainspring and barrel, it has a battery. The battery goes though a circuit with a transistor to a coil. The coil is sandwiched between two wheels on the balance wheel assembly, one wheel has magnets on them  (yes magnets in a mechanical watch!) the coil pulses with the current and the magnets are opposite poles which makes the balance swing. The movement of the balance then transfers its power down the train of wheels, eventually to the hands, in effect moving the opposite way to any conventional mechanical watch which goes from mainspring to balance wheel.  This regulated pulse makes the watch run efficiently and more accurately.  Also gives a sweep second.  The joy of these is you can take them off for weeks at a time and they will just keep going, ever ready to wear! 
This model has a very nice blue faded dial with some wavy lines that do not show up much on the photos.  There is some age related paint loss to the very outside of the dial around 2 o'clock mark but other than that it is in good condition and all original.  I have serviced the movement and fitted a new battery, Please note they do eat batteries so if it stops in 6 months or so its just the battery that has died.  I have fitted a new Sternkruez crystal and given the case and bracelet a refresh by way of cleaning and some light polishing / brushing.  New gaskets to the caseback and crown to finish it off.
The watch party piece is its quickset of day and date.  Done by gravity. Hold the watch in your hand and push in the crown and the date will change.  turn the watch upside down so 6 it at the top and push the crown in again and the day wheel will change!  it has both Kanji and English as options. 
As a vintage watch I would class it as not waterproof so refrain from swimming or bathing wearing this one. 

One last note, the bracelet fits my 7" / 18cm wrist. The end it on the last hole of the clasp so no more extra adjustment can be made to make it bigger. If your wrist is bigger then a bracelet extender can be fitted or of course you can fit a nice strap to your liking. 

Dimensions

Diameter 38mm

Thickness 12mm

Lug Width 18mm

Lug to Lug 41mm