Soyuz Clock 444H

Flown Soyuz Clock Model 444H

I bought this clock at an auction ( It is authenticated to have been flown in a Soyux TM spacecraft, but unlike the Apollo hardware, there is no way to track a particular item number to a specific flight. There are quite a few versions of this clock. This digital clock replaces an earlier, spectacularly beautiful mechnical version.

Video Playlist

Part 1: Discovering the inside

Part 2: Reverse engineering

Part 3: First power up

Part 4: How precise is it?

Part 5: External functions

Part 6: International Atomic Space Clock


You'll find an operating manual from the ISS space station (I believe) and my lab book notes below.

Below is the official ISS translation of the Russian legends

Ken Shirriff's Reverse Engineering of the Clock Innards

Ken Shirriff reverse engineered the clock, and talked about in episode 2.

Ken Shirriff's Soyuz Clock Reverse Engineering Notes

Ken Shirriff Article about the Soyuz Clock

Ken has written a detailed article about what he found:

Soundtracks from the episodes

These are the often requested odd Russian folk sound tracks appearing in the episodes.

The original Tetris game soundtrack, as performed by my Mac SE/30 on a subtle background of disk drive rumble:

The Soviet national anthem:

Soyuz 744H Space Clock Reference Pictures and Dimensions

Several viewers have expressed the desire to make a model or a 3D printed version of the clock. Here are a few reference pictures which are close to orthoscopic and should enable you to get the dimensions once you refer to my sketched overall dimensions. If you ever make a 3D model, please contact me so I can post it here!

Lab Notes

Here are the few doodles I made that show the pinout of the connector

Clock and Quartz Oscillator Precision

In this episode, we use an HP atomic clock to drive the Soyuz clock, and measure the resulting precision of this Soviet-American cooperation.

Here is the diagram of the HP atomic clock external driver for the clock from episode 6

Here is the HP-85 program I used in episode 6 to measure the accuracy of the clock

Soyuz Clock Accuracy Measuring Program.pdf

Fixing the quartz oscillator

We discovered a glitch in our Soviet space clock quartz crystal oscillator. In episode 7, we attempt to fix it.

Here are the reference books on quartz oscillators I use in the episode, and the information about the Soviet IC

Here is the die shot of the Soviet 134LA8 circuit. Die shot is by Ken Shirriff