YouTube User SLvik78

John found a great dekatron based Nixie clock on YouTube that I wanted to re-post here.  All of the timing is derived from the mains line at 50Hz.  The dekatrons divide the time base in to seconds, minutes, and hours.  I've contacted owner and others have as well to see how he performs the "divide by 5" function to get 1pps and the "divide by 6" to convert 60 seconds in to a minute.  You can see the jump/division happen at 1:20 seconds in the video.  I am not sure if this is simply a matter of wiring the dekatrons differently or there are other components in use that are not visible.

If you have an idea how this works, please leave a message in the comments and I will update this post.

UPDATE 7-7-2010:

Be sure to read SLvik's response in the forum.  He shared a photo of the back of the clock and confirmed The 50Hz mains is rectified and then divided down from 100:10 and 10:1pps by the two dekatrons at the bottom.   Very nice work!

Dekatron Clock Rear


Lastly, be sure to check out Kahlo's link for his schematic of a 50Hz divide by 5 & 10 design.  This help quite a bit: (thanks for sharing!)



+2 #1 Guest 2010-07-07 05:30
It doesn't look like he's using a divide by 5. I would expect him to have full wave rectified it and then divided by 100. As for the divide by 6, I'm guessing (in theory; never actually played with dekatrons) you can capacitively couple the fifth cathode to the zeroth cathode, such that when the fifth cathode goes out, it drives a negative pulse on the zeroth, biasing it enough to reset the tube.
#2 Brian Stuckey 2010-07-07 14:03
@kenneth - that makes a lot of sense. Dividing 100 by 10 and 10 would be much easier. I bet that is what the two at the bottom are for 100:10 and 10:1 pps.

As far as dividing by 6, what you suggested makes sense but I don't have any on hand to play with either.
+2 #3 Guest 2010-07-07 19:06
StuckeyYou`re right.

Besides decatrons I used transistors, diodes and photocouplers.

Here`s the photo of the back side of clock.
#4 Guest 2010-07-07 21:08

a working timebase for 230V/50Hz:
First decatron divides by 5, second decatron by 10.

@Stuckey: Nice clock!
+1 #5 Guest 2010-07-07 21:16
@SLvik: Nice clock!
#6 jondaddio 2012-12-25 00:22
The link to the schematic is dead. Does anyone have a copy they can send me?

If so, TIA
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