Restoring the Portobello Police Station Clock

Date: 11th April 2026

I received a message from a companion today with a proposition: "I know we planned on Edinburgh, but would you be up for meeting in Portobello instead to help me fix the clock in the old police station?" For me, the prospect of scaling a dusty, 19th-century clock tower in a derelict police station is the absolute pinnacle of Saturday afternoon activities, so I accepted immediately.

This mission was sparked by a plea from Action Porty:

"Can you help keep Portobello on time? Action Porty has recently bought the Police Station for the community, but we can't work out how to change the time on the clock tower! We wondered if there was anyone in the community with expertise that could advise us of the details for changing the time? Or who best to contact for help?"

One detail I had overlooked: clocks are typically located very high up. Consequently, fixing the clock meant being high up, which necessitated the use of dauntingly steep, long ladders.

Despite my internal whimpering at the thought of ascending into a dark, potentially spider-filled void, I pushed through. I was rewarded with a tour of the attic, which eventually led to a further set of stairs climbing into the heart of the clock tower.

The Clock's Heritage

Upon arrival, we were greeted by a stunning mechanical assembly and three distinct clock faces. Given that construction began around 1877, it is highly probable that the mechanism is original. However, it has been updated over the years; electric motors now drive the system, and a control unit allows the chimes to be silenced during the night.

The building's purpose has shifted several times over the decades:

While I was there, volunteers were hard at work stripping away wood-chip wallpaper and 1970s polystyrene ceiling tiles to restore the building's original architectural splendor.

The Process of Setting the Time

Determining how to adjust the time was the first hurdle. While likely intuitive to a horologist, we were flying blind. We deduced the following mechanical flow:

Small Motor $\rightarrow$ Gear Train $\rightarrow$ Central Shaft (rotates once per hour) $\rightarrow$ Three Face Drives $\rightarrow$ Minute Hands.

To adjust the time, we hypothesized that disconnecting the motor would allow us to rotate the shaft manually. We discovered a pawl on one of the gears; once lifted, the shaft turned freely.

The "Inside-Out" Perspective

Because we were standing behind the faces, we had to rely on the counterweights. We estimated the hand positions by imagining the actual hand was opposite the counterweight. At one point, we panicked, thinking the clock was running in reverse—only to realize we were simply viewing the mechanism from the inside.

We descended to street level to verify the time. Phew—it was correct and moving forward.

Technical Analysis of the Control Box

The original 1877 machinery had been augmented with a modern control box. This unit was certainly not Victorian; it featured a PIC 16F628 microcontroller with a date code likely from 2001.

Hardware Components:

• Relays
• Power supply
• Lead-acid battery & charging circuit

The box is nearly 25 years old, but it remains functional. We are unsure of the battery's current health or who originally engineered the circuit, as there were no labels. The only user interface was a cryptic button labeled "advance".

Logic Summary (TLDR)

Detailed Findings:

• Chime Control: The box manages a mains-powered blue motor with a chain that operates the striker.
• Feedback Loop: A switch on the striker informs the box how many chimes have occurred so it knows when to cease.
• Timing: A switch on the clock shaft triggers the box exactly on the hour.
• The "Reset" Switch: This appears to kill power to the clock motor. (I suspect it also resets the internal counter to midnight, but this is $\text{TBD}$).
• The "Advance" Button: Must be held for several seconds. Upon release, it triggers the chime for the subsequent hour.
• Time Setting: The hour is set by repeatedly pressing "advance."
• Status LED: Flashes a specific sequence: Long, Long, Short, Short, Short.

Key Technical Note: The box contains no actual "clock" (quartz/oscillator); it is simply a counter that increments based on the mechanical "hour trigger" switch.

Connectivity:

• Banana plugs for the two switches.
• Cables for GMT/BST toggle.
• Mains power input.
• Clock motor output.
• Chime motor output.

I attempted to convince my companions to let me test the system by making the clock strike thirteen, but they were far too sensible for such antics.

Final Results

We waited until 4:00 PM to verify the timing. We checked the exterior faces, and the time was spot on. Ironically, 4:00 PM was exactly when we had to leave.

Due to concerns from some neighbors regarding the noise, we disconnected the chime motor to keep the peace. To celebrate the success, we took a quick tour of the police cells before heading across the street to the Portobello Tap for a well-earned beer.