Hello!

I'm building a count down counter with 74191 chip and intend to activate it using a push button. Already built a push button with switch debounced and it outputs a 1 second pulse. But I'm stuck at what appears to be a simple problem - how do I activate the counter only when the button is pressed?

Can't connect the debounced pulse to the Count Enable input because it's just a pulse, thus it will only enable the counter for one second. I thought of connecting a JK-Flip Flop to the push button, toggling the state. Is there a simpler way than this?

PS: I'd like to know a simple way using push button; for DIP switch it's straightforward - just connect the output to the Count Enable, since it will always remain asserted once switch is on.

 

Can you use another pushbutton switch? A latching switch will remain on with a single press. Something like the switch in this link.
http://www.adafruit.com/product/1478
If not, then I think using a flip flop is your best bet.

 

I see. Thanks DJ!