Climbing a Dusty Clock Tower to Save a Scottish Police Station's Time
Fixing the Portobello Police Station Clock
When Action Porty bought the old Portobello Police Station for community use, they couldn't figure out how to change the clock tower's time. A friend's invitation led me up steep ladders into a spider-infested attic and onto the original 1877 mechanism, complete with electric motors and a chime control. The building, once a library and police station, is now being restored by volunteers.
I suppressed my whimpers at climbing up the rather high, steep ladder into the likely spider-infested darkness and was rewarded with an explore of the attic, which lead to another set of steps which went to the clock tower itself.
- walrus01
My first thought was it'll be a lot easier to maintain if they put some sandpaper-like grip tread on those wooden ladder/stair steps. It comes in self-adhesive rolls, you peel and stick. Huge safety improvement for very little cost.
Without modifying anything intrusive to the mechanism, a cheap way of monitoring to make sure it's still running OK would be to install a low cost PoE IP camera mounted in such a way that it's aimed at the gear mechanism, then feed its video into something like Frigate. As cheap as $75 for a camera, some cat5e cable and staples to take the cable to where you need it, and an old desktop PC (plug it into anything that gives it a DHCP lease and default route outbound, make it a VPN client). You could also possibly use the camera to monitor the blinking status LED without doing anything intrusive to the existing electronics.
One other random thought: The battery in that photo looks like exactly the same size commonly used in emergency exit stairwell wall mounted battery-backed lighting systems, it's a 12V 7Ah to 8Ah AGM lead acid, rectangular/flat size. It should be fairly easy to find a replacement if needed from a local distributor of commercial electrician supplies/parts. Those things should go on a fairly frequent replacement schedule since they're held at 100% state of charge near constantly, and that one is probably exposed to hot summer sunlight temperatures in June/July/August. As a general rule if you don't know how old it is or have any reco […]
- grahamburger
How fun! Once, after climbing around in a dusty old church attic like this, I had to head straight to the airport for a flight. Barely made it on because something in the dust kept flagging as dangerous. They were using a test strip on my backpack and clothing and analyzing it in some kind of machine. Stressful as I was already pressed for time! Finally got a clean test and they let me through.
- Animats
The clock machinery isn't really doing much any more. This clock no longer needs winding, and it looks like the weights are gone. There's a small motor powering the time train. That's the little one at the upper right. The pendulum is still in use, but if they used a synchronous motor and a toothed belt, the pendulum and escapement would be unnecessary. The clock would just sync to the 50Hz National Grid. There's no visible mechanical backup for the time train. After an power outage someone is going to have to climb up there and reset the thing.
The big gearhead motor with the roller chain powers the chimer, and, apparently, its schedule is totally controlled by the PIC microprocessor. There are remnants of a mechanical striking train at the lower right. Notice the curved rack. It doesn't seem to be doing anything. Usually there would be a snail, a stepped cam that tells the chimer what hour it is, read by a cam follower attached to the rack. That may have
been present at one time, but it's gone now.
The chimer apparently gets tripped on the hour, but has no idea what time the time train is displaying. So time train and chimer CPU have to have their hour set separately.
- dwayne_dibley
This is what I want the internet to be. Great read.
- ad133
Wild seeing local stuff on HN. My dad used to work in that police station, probably the first (and only) HN story I’ll send him.
- aviperl
> If we were to fix the clock we would be next to it and so we would also be high up. And being high up involves heights, and steep long ladders are needed to get up high.
Human writing, Claude could never!
- SaberTail
> The "Status" LED flashes some kind of code - long long, short short short. I assumed the number of flashes would correspond to the time but apparently not. We didn't have time to figure this out before we had to leave.
long-long-short-short-short is 7 in morse code. They don't say what time they tried this or if it ever changed, though, so that's just a hypothesis.
- IsopropylMalbec
The battery on that circuit looks very much like a backup battery we have connected to our house alarm.
We moved in to the house in 2003 and that battery died this year, so I would imagine that it is already or will very soon die. That said, if it's a backup battery and the electricity supply is stable then it may not make any difference.