Ok so i was looking around for a electronic code lock. Ended up find this. Attached below. well it uses a cd4017 which i never worked with before. I understand the diagram. I just have some questions. first do i have to use Q1-Q9 and output on Q10 or can I make my code shorter and just use Q1-Q4 and output on Q5? Also i can wire all the non-code keys to S10 for reset? So if the wrong key is pressed it will reset the chip. And can i use a 2n3904 transistor? The diagram calls for a sl100 which i am having problems finding. but i have about 100 2n3904. thank you for any answers you can give.