Hi All,
I am trying to construct a test rig that will send clock pulses to some boards that have a 4013B flip flop wired as a latch. Rather than directly connect the output of a signal generator to the clock input I thought it would be fun just to add some extra complications and drive the clock pulse from a mosfet instead and drive the gate with my signal generator (Rigol DG822).
This is the circuit:
![](https://www.eevblog.com/forum/beginners/signal-generator-clock-pulse-issue/?action=dlattach;attach=821100)
For my reference I have an LED also on the source so I can visually see the clock pulses get sent, however, an interesting thing happens.
My signal generator is set up sending a PWM of 1hz and duty cycle of 10%:
probed at the mosfet source:
![](https://www.eevblog.com/forum/beginners/signal-generator-clock-pulse-issue/?action=dlattach;attach=821106)
You will notice the first pulse is when I enable my sign gen output, you can see the rise time is much longer than the other pulses, here is the first pulse on its own:
![](https://www.eevblog.com/forum/beginners/signal-generator-clock-pulse-issue/?action=dlattach;attach=821112)
Here is the second and beyond pulse:
![](https://www.eevblog.com/forum/beginners/signal-generator-clock-pulse-issue/?action=dlattach;attach=821118)
This long first pulse is causing the 4013bs to go wobbly as its a invalid clock rise time but why does only the first pulse do this?
I have connected my sig gen directly to my scope input and every pulse is perfect, so it must be my circuit to blame but I am not sure why.
Any help would be appreciated.