I'm in the process of turning a Raspberry Pi project into a simpler circuit board powered with 555 and 4017 chips.
I want to be able to start by showing 7 LEDs, then go to 6 then to 5 and so on until all are dimmed.
I'll take a simple example with 3 LEDs: LED 1 lights if the board is in state . LED 2 lights if the board is in state [0 OR 1]. LED 3 lights if the board is in state [0, 1 or 2]. Nothing is connected to the board for state . Thus in the board's state of 0, LEDs 1, 2 and 3 light. In state 1, LEDs 2 and 3 light. In state 2, only LED 3 lights. In state 3, nothing lights.
I had tried using the step by step outputs of the 4017 chip and diodes to form an OR circuit, but I think I have all the LEDs in series (draining too much voltage) so the resultant brightness with more than a couple of LEDs is terrible.
Question 1: How can I have the LEDs counting down (AND with good voltage to the LEDs when they are lit), as above?
Question 2: The LEDs are just one half of the circuit board. How can I make sure that once the 4017 chip enters its eighth state, the LEDs STAY off (until the circuit board's power is turned off and on again)? The examples I'm finding on the web seem to circle continuously. Thanks.