Hello, can someone take a look at my simulation settings and let me know what I am doing wrong? For some reason, my counter outputs never change state. Played around with this for about an hour or so, I know there is some setting I am missing somewhere. Any help is appreciated.

 

The input clock voltage must be the same as Vcc.
Is it?
It looks like you are using only 1V.

 

The input clock voltage must be the same as Vcc.
Is it?
It looks like you are using only 1V.

Yep, both Vcc and the clk are 5V

 

Hello, can someone take a look at my simulation settings and let me know what I am doing wrong? For some reason, my counter outputs never change state. Played around with this for about an hour or so, I know there is some setting I am missing somewhere. Any help is appreciated.

The 74393 clock input is active low.
Try pulling the clock input high to 5v (instead of low) thru the resistor.
The PB should produce a signal from "open" to low(GND) to clock the 393.
(Use a switch (or PB) component for the PB)

 

Below is the LTspice simulation of the circuit:
Don't know why your simulation doesn't work.

 

Below is the LTspice simulation of the circuit:
Don't know why your simulation doesn't work.

View attachment 254716

Yours works because the voltage source output is either at 5v or 0(GND). So the 393 will see a falling edge transition at its clk input.

 

Should really be tested this way..



If you change the PU resistor to PD it won't clock the 393.

 

Thanks for the help everyone. I tried all of the suggestions and this still doesn't work. I wonder why.

 

Thanks for the help everyone. I tried all of the suggestions and this still doesn't work. I wonder why.

Perhaps you have a bad model.
Did it come with OrCad Pspice?

 

Perhaps you have a bad model.
Did it come with OrCad Pspice?

Yep, came with the software. From what I've read, the red lines indicate the line is at an indeterminate logic level. I've tried two different counters and have the same issue by the way.

Anything special I need to do in my simulation profile?

 

Anything special I need to do in my simulation profile?

None that I can see.

 

None that I can see.

Found the problem! It was the DIGINITSTATE parameter. It defaults to an unknown state. Changing the X to 0 fixed this.