I have a partially blind parent with some dementia. We could use a wall clock with date, time, name of day. All the ones on the internet are 7-8 inches diagonally. I’m thinking about 20-24 inches. Do you think this is doable with an arduino or equivalent and a display? Would I use an LED display or an old TV/PC display?
Ready-made dot matrix displays are smaller as you said. If you make one by yourself, that can be an option. You can at first design and print your own PCB. Then solder all LEDs, ICs etc. There are many companies that customize digital sign boards according to the customers’ requirements. You can contact them. Here is also a Raspberry Pi-based full-screen clock tutorial. You can check this too: https://www.ampron.eu/article/use-case/ … pberry-pi/
GPS precise timing: The GPS synchronous timing system has high timing accuracy, wide range, high reliability, and is not affected by various interferences all day long.
NTP network timing: First, reset the correct time of the LED electronic clock, insert it into the network cable, and wait for a few seconds to complete the timing. The internal accuracy of NTP network timing reaches ns level, and the network timing accuracy can reach 1-50 milliseconds in different network environments
CDMA telecommunications time calibration: The CDMA electronic clock can automatically calibrate the time directly through the telecommunications 2G or 3G network.
Raspberry Pi with a clock app maximized to fill your screen. Connect that to a small TV or computer monitor. The pi is small enough to live stuck to the back of your TV/monitor and if it’s a pi zero w and the TV/monitor has USB, you might even be able to power it directly from the display.
The pi can grab current date and time from the internet via WiFi.