Day 17 – Culbokie

Leitch studio clocks…

In another life I worked for the BBC. Still do from time to time, in fact. The things that have always fascinated me in their premises are the Leitch studio clocks. If you have ever seen a shot of a radio studio or a TV gallery you will probably remember the big square black clocks with illuminated faces. They are a beautifully understated design, in my opinion – the epitome of function first.

That’s only part of the story, though. In order that every clock in the BBC showed the same time, they were controlled by time code from a master source. If a clock lost the signal, it would get slightly miffed and display a red light under the ‘6’. The hands were individually controlled by stepper motors and as a result could, if required, move in different directions at different speeds. When the TC source was re-established, the red light would flash. The hands would whizz round to about ten seconds ahead of the correct time, stop until the world caught up then start again. (Older versions were even better – the hands would began by rotating clockwise together, but stop one-by-one at 12. When they were all there, they moved downwards by the shortest route to the correct time – a balletic, if somewhat mind-blowing sight. Here’s an older Leitch beginning the journey down from 12…)

Not too long ago, I was in the right place at the right time and was offered a clock that was surplus to requirements (requirements being ‘digital modern, analogue old hat.’) The first problem was that the cold-cathode illumination had failed. The second was that I desperately wanted it to be synced to TC rather than free run. Eventually I found an app for an Android phone that generated time code. Free if you only wanted it for time-of-day. Perfect, I thought. Sadly not. The output level from the phone wasn’t enough for the clock.

Undeterred, I bought a miniature 5V amplifier. With the phone up to 80% level and the amp at full, the clock synced! Hooray! The following morning, however, it had lost lock. The phone had run foul of the Android police, who were concerned for my hearing and had turned the level down after a few hours. The only way round that problem was to buy an ancient phone with an earlier Android OS from a time when health and safety regs weren’t so rigorous.

Next, I bought an LED light strip to replace the illuminator. That worked beautifully. Now to power everything – phone, amp and strip – from a 5V SMPS. It needed 4A, but it worked, and was nicely compact. Most of the 4A was needed by the LED strip, so to give the power supply an easier time, I thought I’d use a PIR to switch it on and off. I bought one advertised as working from 5V – turns out it needed 6V. Fortunately the SMPS could be tweaked to give 6V… but that was too much for the phone and amp, so I had to buy two tiny 5V USB regulators!

So, as usual (e.g. this virtual walk and ever expanding website) a simple job became complex. But it works! All I have to do now is fit everything into or onto the case of the clock. That is still an ongoing task. But it’s early days – I’ve only been thinking about it for a year.

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