Look on Hackaday for "Why do you need to use decoupling caps". I am not seeing any talk of decoupling caps in any of this persons writeups. Maybe they are there and I am just not seeing them. It used to be when designing with LS ttl you needed one per chip to make sure switching noise did not get onto your power supply rails.
Otherwise, a great project for learning.
The decoupling caps are there in the schematics shown alongside the symbols for the IC power inputs which is a common way of doing things.
IDK why something as fundamental as decoupling caps should be mentioned here at all though, anyone sufficiently knowledgeable to make use of this information would know that they're required already.
