One Minute Power:
I am trying to implement a one-minute power function, as shown in the picture , but for some reason the capacitor won’t load in the spice simulation. What am I doing wrong?

 

R2 is wrong. You have it set to 6.2milliohms! Try 6.2meg.
Welcome to AAC!

 

You made a common Spice syntax error.
A 6.2m resistor is 6.2 milliohms.
You want 6.2meg.

And note that V1 is a voltage not a switch, so when its voltage goes to zero, the capacitor will rapidly discharge back through R1.
You want to use the switch (sw) model to simulate the push button and use V1 to control the switch.

Also, R3 should not go to that node.

Here's the simulation with those changes:

 

Note that in the original circuit figure 1.38, the output pulse width is 1 minute *plus* however long you hold down the button. If you camp out on the button for 30 seconds, the total output pulse width will be 1.5 min.

ak

 

YES,
thank you all about circuits forum!
you guys solved a big headache!

 

YES,
thank you all about circuits forum!
you guys solved a big headache!

Unfortunately, simulators do exactly what you tell them instead of what you meant to tell them.

 

Unfortunately, simulators do exactly what you tell them instead of what you meant to tell them.

Just like real circuits operate exactly as they are wired not perhaps as how you want them to.