Disable outputs, 74LS24x

[stevendt]

Hi,

newbie question please . . . . . .

I have the following circuit which will be part of a diagnostics card for a hobby system that I am buildiing. It is intended to turn on some LEDs based on the status of the inputs to the LS240. I would like to have the option to easily disable all of the LEDs, i.e., turn them off. If I set /1G & /2G HIGH, I think that the outputs will go tri-state?

Will the tri-state outputs be enough to keep the LEDs off? - I don't have enough space on the prototype board to include additional pull-ups.

(The enable inputs are currently shown open, but are actually tied to 0V in the design at the moment)

regards
Dave

 

[ronsimpson]

This circuit should work fine. You can turn off all the LEDs with the disable pin.

 

[stevendt]

Hi Ron,

that's great - thanks a lot for the super-quick reply!

regards
Dave