Need help with my project, a combination lock in proteus

Thread Starter


Joined Dec 11, 2023
So im trying to make a combinational lock in proteus. One of the issue i've come across is one of my button which is labelled "reset" output high even if its not press but when I connect a logic probe to the line, the cable becomes normal. The second issue is there is a sequence detector that output 1 when there is 1111 input sequence, it was working as intended but when I add the button labeled reset, the said detector output 1 when the input sequence is 111 and 1111. Im also open for suggestion to improve my project, thank youScreenshot 2023-12-11 190839.png



Joined Jun 8, 2013

1. You are mixing IC families. That is bad for various reasons. Use only a single IC family. I suggest using CD4000 family unless there is a compelling reason not to (like hi speed, for example, which is not a requirement for this circuit).

2. Implement a POR (Power On Reset) circuit to initialize all devices to a specific state (like FF's for example), or the circuit could power up in an unknown state.

However, I did try the reset button and it behaved normally (output hi when pressed, low when not pressed).

Re-post your circuit after you've changed the circuit to use one IC family (preferably CD4000)