comments:
Are 7 segment LED displays OK? If so take a look on eBay or Amazon or someplace. Amazon has 1.5 inch led displays at 6 for 14 dollars. If you want to go bigger they get pretty expensive, like 10 to 25 dollars each. You could also just get a bunch of individual LEDs of the color you like, say the 5mm ones, and do the printed enclosure so that could be inserted to make either 7 segment displays or maybe a 7x9 or larger array for dot matrix digits. You’ll need drivers to run them from any processor since the processor pins can’t handle the needed currents. Lots of stuff out there on doing this and just uses some simple transistors and Darlington transistors or some FETs, a few dollars from Mouser electronics. You’ll probably want to run them in a multiplexed setup- look that up. Basically one driver for each digit and 7 drivers for all the segment lines or if dot matrix one driver for each dot in one displays. Basically all the dots are hooked together and you light one up by driving one dot driver and one digit driver. Yo basically do one digit then move on to the next and do it over at a rate about 100 times a second and it looks solid, but you need to drive things with a bit more current to compensate for not being on all the time. This setup uses less pins on the processor. You could get some breadboards to prototype this with a raspberry pi pico which is plenty of power. Get a pico W if you may want to connect it to the internet via Wi-Fi at some time to set the time automatically. Get a pico and learn to program it, probably in python. It has libraries that will handle the low level interface to the hardware for you. You can get keypads like 3x4 telephone style for a few bucks and they are easy to scan for presses with the pico. A few other switches and LEDs and you have the parts. Power supply is probably the type that plugs Ì to the wall with a cord to supply 5v to the unit at 2 to 3 amps depending on the didplay size you pick. And if you want it to keep reasonable time, a real time clock chip - you can get one on a little breakout board for a few bucks. I’d suggest you start by getting a pico, maybe one of the kits that comes with some parts and a breadboard something like this https://www.amazon.com/LAFVIN-Ultimate-Starter-Raspberry-Tutorail/dp/B0F26D2QRJ/ref=sr_1_7?crid=2EY7UX7979EQA&dib=eyJ2IjoiMSJ9.DSdBSCg_evPvGtjN6Be4A_EvUWIqQqwRL_3x4QDQUt_QncR1UTMGeNijbcGn7EAR3yM7pEZB-Kumj_hwSSaLc9fIr7aW5EkxpI_0ZLEcLciDM8x6Pw6xMaJrrRkU8aXDFfEg3H39-dsm_J_S0MltzFYfbhyv8WPGB4nG0Vwgo-2ePHOnC5o3vQWHpbWuSms17rOWIEelh_DAE2vW3Y_N5iiuikTxZpnKLt8J8Anrwdg.BhK0R__ymIKUAwCxyeksw8dtNR9owB081iYcPzgNTgY&dib_tag=se&keywords=raspberry+pi+pico+w+starter+kit&qid=1779304859&sprefix=Pico+w+kit%2Caps%2C270&sr=8-7 For around 25 to 50 dollars depending on what you get. It actually has all or most parts you’ll need to build a smaller version of your clock/timer then just scale it up. You can get extra transistors from Mouser.com. It will let you find out how you take to programming and simple electronics before you try sourcing the larger parts. Hood thus is helpful.