More speculation: Found an Alarm Keyboard @ $ 1.49. Electronic Goldmine, G 17927; 12 keys, 16 wires, 6 LEDs. Might have a wire per key which if true, & using storage, would allow entering 4- 3 bit nos. or 3-4 bit nos. Dip SWs still used for internal combination. If interested in 3 numbers, I might buy one to check it out. If as expected, could send it on. Need a few parts anyway.

 

Thanks again everyone.
We normally do 5 fun projects to one learning project some on her bread board some on her PLC but she gets to pick all projects including this one, she picked what or how the lock functioned but it was above me and that is how I found you when I was out looking for help with what components I needed go get and a schematic of how it should look or be assembled. Like I said it is above me but I don’t want to be the reason she does not succeed even if it is just a whim. I went to the hyperlinks you gave me and bookmark them for later. My daughter has a logic probe and a fluke multi-meter. The logic probe was a project we made with a yarn needle and needed components. Have a good day everyone and thanks.

 

Thanks Bernard you have been very helpful,
I have some more questions, a man at work said to design this circuit as a state machine. I have seen this done on PLC's but did not know it could be done with gates is it true and how would I start to find out about it and is it worth learning so I could teach my daughter it?