Hello, djs. Are you sure you meant to tag me? I'm not a participant in this thread. Didn't you mean a different thread, or was this thread split from a previous one in which I was a participant?

Oops! Meant @crutschow !

 

@crutschow : what’s the purpose of R3 and C4? And is R1 really necessary? And although the CD4013B power connections aren’t shown, shouldn’t a 0.1 uF decoupling capacitor be connected between Vcc and ground? Just asking for my own curiosity.

 

Hello everyone. Just wanted to say thanks for the help. I got my project working great now. Really appreciate it!

 

what’s the purpose of R3 and C4

Do you mean R3 and C2?
They provide a power-on reset in case you want to insure that the output will be off when power is first applied.

And is R1 really necessary?

Yes, if the input is from a mechanical contact.
R1 and C1 provide contact bounce protection by generating a delay in the D input feedback, so that the FF can only change state once for the duration of any input contact bounces.

shouldn’t a 0.1 uF decoupling capacitor be connected between Vcc and ground?

Good idea.

 

I m

Do you mean R3 and C2?
They provide a power-on reset in case you want the output to be off when power is first applied.
Yes, if the input is from a mechanical contact.
R1 and C1 provide contact bounce protection by generating a delay in the D input feedback, so that the FF can only change state once for the duration of any input contact bounces.
Good idea.

I meant C3 and R4.

I got the power on reset part. And my understanding of the problem was that the input was NOT a mechanical contact. If it was, I understand.

 

I meant C3 and R4.

Those are left over from the original design, which was for an automotive application.
It provides filtering for the noise spikes that can occur in vehicle power.

 

And my understanding of the problem was that the input was NOT a mechanical contact.

The statement below is from the TS's first post so I assumed it was a mechanical contact.

Basically, a push button turns relay on and keeps it on. I push the button again and it turns relay off.

 

Not to be argumentative. I saw the following

My pulse source is from a counter that sends a 20ms signal to my relay.

...and I thought it wasn’t mechanical. No worries.

 

Perhaps he was using the PB circuit as an example of what he wanted when the input was a pulse from a counter.

 

I just came across this thread, the functionality seems to be similar to a project that I repaired many years ago.
But I have a big question, which is what sort of motor reverses instantly? And one work-around for a short counter pulse is to use the greater or equal function instead of only the equals function.
And with an encoder like the one shown it might work to have the counter count up and then count down. Some of them will work that way.
And please describe whatever the actual solution was so that we can all learn something.