I’m looking to see if there is a circuit I can build that would light up a row of about 20 LED’s one at a time after pressing a button, and keep those LED constantly on once there were activated. Finally, when pressing a button again, they all power off one at a time in the same order?
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Have a look at a chip family called "shift registers".
For example, a TPIC6595 will drive up 8 LEDs. You simply cascade multiple shift registers to drive more LEDs.
Have a look at that chip, then modify your question with what you have learned.
We will help you get to where you want to be but you have to do the work yourself.
answered Jun 17, 2015 at 21:29
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\$\begingroup\$ Thanks, "shift registers" put me on the right path! A few 74HC595 combined with a programmable ATMEGA328P should do what I need. \$\endgroup\$ Commented Jun 18, 2015 at 3:47
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\$\begingroup\$ Be aware that a 74HC595 is only rated for 6 mA per output. If you want to drive your LEDs harder than that, you can usually get away with it, but you are in territory where the manufacturer doesn't guarantee the chip to work well. The TPIC6595 costs a bit more, but it will handle LOTS more current. \$\endgroup\$ Commented Jun 18, 2015 at 4:32
1s in, if clocked properly.. \$\endgroup\$