This Week’s Featured Watch #18 – Cosmotron 7806

This was my first Cosmotron, and was almost a ‘just curious’ buy. But as soon as I received it I was rather hooked and I have bought a few more since. I’ll be doing an article on the Cosmotrons in due course, so not too much technical information here for now – enough to say that these are ‘hybrid’ electro-mechanical movements, and Citizen was the first company to make them for the Japanese market in 1966, see here:

The first models ran at 18,000 beats per hour, but this soon increased as the movements were updated, and the 7806 runs at a smooth 36,000 beats per hour, whilst the speed reached 43,200 beats per hour in the 5800, see here:

Fancy dials and faceted crystals are seen on a number of the later Cosmotrons, but this one is a simple design, giving it a timeless quality in my view:

The white dial carries the usual applied Citizen logo, with printed ‘electronic’ and ‘cosmotron’ logos and the applied Cosmotron symbol:

Some nice finishing on the day / date window frame and a smart hand set:

The movement, with battery & electronics instead of mainspring, with relatively conventional hairspring and balance (with fine adjuster):

Although the expected battery life was only about 12 months, mine has been running now for at least 21 months, and keeps very good time.

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4 Responses to This Week’s Featured Watch #18 – Cosmotron 7806

  1. Ophir says:

    Today I got my first Cosmotron and it is a 7806. I just wanted to comment your statemen about bettry life expectance: Don’t forget that a lot has happened in the battery technology since the ’70s of the last century. So it is not surprising, that yours is running strong for twice the original estimation. Since we are at it, can you tell me which battery to look for, to make my newly arrived Cosmotron run?

    • sweephand says:

      Hi scoobadoo, congrats on your first Cosmotron 🙂 Your point about batteries is well made, and no doubt explains the better performance.

      The battery I use is the Renata 357 – as recommended by Paul at Electric Watches who is a guru on all vintage electrics. Well worth visiting his site if you’ve not already done so. If you click on the movement gallery images you will see the battery type. And his ‘batteries’ page gives you the different manufacturer codes. Here’s the link: (also in the blogroll)


      • Ophir says:

        Thanks Stephen!
        With your Information I found out that I actually have a battery to fit in my drawer. Okay, it is not a Renata, just a cheap Alkaline. But for the test it is enough and it may even run longer that the promissed year 🙂
        It is such a relief to see that the watch is running, and the sound of 36000 beat is just a symphony to listen to! I can now go to bed happy!
        Thank you again!

  2. sweephand says:

    You’re welcome, nothing better than going to bed happy! 🙂

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