i am doing this same project (without the piggy bank), i have a 2 part question..
1.) if i do use a power supply, how do i hook up battery pack in-case there is a power outage to remain working?
2.) how do i save the data (what has already been counted) if say battery dies and or power loss with out a battery supply?
basically i just want to save the dollar amount in-case i lose power regardless of how i have this powered... so when it's powered up, the dollar amount was not lost and remains intact to continue on counting/adding to the dollar amount.
thanks in advance,