Upgrades

SMART PHONEBOX

Slightly off the topic of Payphones I appreciate,  but I decided to make the overall Kiosk slightly smarter.  Underneath the false floor of the Kiosk I installed an Arduino Uno WiFi Rev 2 in a weatherproof enclosure.  This is the brains of the Kiosk and has connections to the Door reed relay contacts as well as the light fitting in the dome.  It also knows the ambient light level outside the Kiosk, so when the door is opened, if it's dark enough, the Internal light will come on automatically.  I also fitted an Air Freshener that is seen in a number of Kiosks out on the street. The motor drive is wired into 2 relays, which operate once a day to provide a squirt of spray in the Kiosk. This is fed via a 5V to 3V step-down circuit to remove the need to have batteries fitted in the Air Freshener unit.   The light can also be operated manually via a radio Keyfob and/or timer module.  The Kiosk is also fitted with a Temperature & Humidity sensor with readings sent via MQTT into a Home Assistant server running on a Raspberry Pi in the house.  Finally, another relay interrupts the 12V AC supply to the Payphone once a day to reboot it, primarily to stop it trying to call the BT management platform.

Lighting

The K6 is usually fitted with a single 8watt, T5 300mm fluorescent tube in the dome of the Kiosk. In some areas,  dual fluorescent tubes are fitted for additional security.  With the ban of fluorescent tube sales in February 2024 and a desire to make the Kiosk "smarter", I decided to install LED lighting instead. Initially, I simply swapped the tube for an LED equivalent.  This was a 5W 12V DC Warm White (3000K) tube fitted with 66 x SMD3528 providing 500lumens output. 

Subsequently, I decided to upgrade this configuration using LED strip lights. 

The next design was to cut a 2mm piece of Aluminium, 280mm x 75mm and mount 6 strips of 12V WS2815 LED's power from a 300W 12V transformer, mounted to the underside of the light fitting mounting plate, where the old switchgear used to be.  I fed power to each of the 6 strips of LED's at one end, and extended the data line from the end of the previous strip to the next strip.  This proved to be my mistake with this iteration!  I think I made the data line too long and the entire array of LED's would only work as 2 x sets of 120 LED's instead of 1 array of 240 LED's.  In order to aid the transfer of heat onto the Aluminium plate, I removed the self-adhesive backing that came with the LED's and replaced it with some thermal-transfer adhesive tape obtained from Amazon and this seemed to help keep the LED's cool.  

Third time lucky.  2mm Aluminium plate again, this time with 240 x 5V SK6812 RGBW LED's mounted onto it.  Each of the 6 strips were power-fed from one-end,  and the data line was kept as short as possible.  Thermal adhesive tape was used once again, and to provide some additional support,  cables were wrapped about the LED's and Aluminium plate at each end and across the centre point. 

The key difference with the SK6812 LED strips is they have a separate Warm-White LED built in to each LED unit.  Whereas previously, White was generated by turning on the Red, Blue and Green LED's, with the SK6812 strip, only the White LED is illuminated, thereby drawing less current and running a lot cooler.  In order to produce the same amount of light as the original T5 Fluorescent tube,  the LED's only need to be illuminated by 20% .

Inside, the light fitting looks like this.

Finally,  because the LED's are RGBW ............