This countdown clock appears on the screens in Matter Of Life And Death ("Eagle Lift Off"), Black Sun ("Forcefield Test") and Collision Course. It is also used, but not featured, in Earthbound.
None of the screen graphics in Space: 1999 were generated by computer. They were all created either by simple oscilloscope traces, or using a live TV camera to film a photo or a prop, or video playback of a combination of these. These shots were created by filming a prop countdown clock that had been built for the 1969 film Doppelganger. The clock appears at the front of the mission control set; the countdown hours/minutes/seconds are dot matrix display, with a 3x10 matrix of bulbs per number. In all cases, the bottom label is "Counting".
The green background is grey on the black and white TV monitors, while the labels are back-illuminated.
In the UFO episode "Conflict" it is used on a TV screen, just like in Space: 1999.
The prop was also used in UFO in the episode "Close Up", and we get a good impression of the size of it.
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Page copyright Martin Willey