CD4013B: Toggle switch not latching

Peter Bregman

Part Number: CD4013B
Other Parts Discussed in Thread: SN74HCS74

I'm trying to use a CD4013 to create latching multi-part switches actuated by momentary SPST switches. Unfortunately, the outputs (Q's and Q-bar's) only toggle while the switches are depressed, and return to the original value when the switch is let up - in other words, the output is not toggling, it's reacting in real time to the switch position. Here's a schematic of my circuit:

over 5 years ago

0 Dylan Hubbard over 5 years ago

TI__Mastermind 46275 points

Hey Peter,

Can you show scope shots?

Also I'd check out the SN74HCS74 device. In the applications section, you will see a similar application. It may work better for you.

0 Peter Bregman over 5 years ago in reply to Dylan Hubbard

Prodigy 20 points

Unfortunately, all the logic is running at 9V B+ and I'd like to use a SOIC package to make hand-soldering easier (still working on prototypes). I think CD4013 is my only option with those criteria. I'll try to take a look with a scope soon. If the issue is input sensitivity, would I be better off using using a Schmitt-Trigger inverter like CD40106 instead of CD4049?

0 Dylan Hubbard over 5 years ago in reply to Peter Bregman

TI__Mastermind 46275 points

Hey Peter,

Yes that will be a better option. The slow edges from the debounce circuit is probably causing issues. Schmitt-trigger inputs will not have issues with slow edges.

Logic

Logic forum

CD4013B: Toggle switch not latching