i M getting an errow when i try to simulate the circuit .Its saying unknown subcircuit called in .

Can some one let me know what is wrong with the circuit. I have placed the files in LTspice@groups.io | Files .

You have used a 74HCT00, but you have included the 74HC.lib library, which doesn't contain a model for this gate. You need to use the correct library - 74HCT.lib.

You have also placed 50p capacitors in series with the 74HC00 inputs. Why? That almost certainly won't work. They should be connected directly.

I also noticed that you are a using a supply rail of 10V, but the 74HCT series logic is only rated for up to 5V operation. In reality, this will blow up! If you need to run at 10V, you must use a different gate - perhaps the CD4011B.

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