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Cmos bistable momentary push button help

diy didi

Member
Hi guys.
I have a need for a simple Cmos IC type bistable circuit.
My requirements are:
Must be able to work with 12V supply
Must have two output pins that go “hi”. If one goes HI, the other toggles LOW, and visa versa.

I have had a look at the 555 timer but it only has one output pin.
Any ideas would be much appreciated.
Thank you.
 

crutschow

Well-Known Member
Most Helpful Member
A 555 will work as a set/reset bistable circuit, not readily as a toggle flip-flop.

Here's a push-button controlled, bistable circuit using a CMOS CD4013 D-FlipFlop that includes a debounce function (R1-C2) for a mechanical push-button.
The Out and Not_Out are complementary outputs.
It can operate from a 3V to 15V supply.

118927
 
Last edited:

diy didi

Member
A 555 will work as a set/reset bistable circuit not readily as a toggle flip-flop.

Here's a push-button controlled, bistable circuit using a CMOS CD4013 D-FlipFlop that includes a debounce function (R1-C2) for a mechanical push-button.
The Out and Not_Out are complementary outputs.
It can operate from a 3V to 15V supply.

View attachment 118927
Thank you soo much. Appreciate it.
 

diy didi

Member
A 555 will work as a set/reset bistable circuit, not readily as a toggle flip-flop.

Here's a push-button controlled, bistable circuit using a CMOS CD4013 D-FlipFlop that includes a debounce function (R1-C2) for a mechanical push-button.
The Out and Not_Out are complementary outputs.
It can operate from a 3V to 15V supply.

View attachment 118927
What is the function of R1 and c2?
 

audioguru

Well-Known Member
Most Helpful Member
R1 and C2 prevent the pushbutton contact bouncing from causing many alternations of this circuit when you push the button only one time.
You did not mention how much output current you need then the CD3013 might be too weak.
 

crutschow

Well-Known Member
Most Helpful Member
What is the function of R1 and c2?
R1 and C2 delay the change in state of the D input (which occurs at about 1/2 the supply voltage) until any switch bounces has passed (delay time about 0.7RC).
Thus the flip-flop can only change state once, no matter how many switch-bounce clock pulses occur within that delay time.
Once past that delay time, the D input goes to the opposite state, and the FF can again change states from an input clock pulse.

Make sense?
 

crutschow

Well-Known Member
Most Helpful Member
So basically a debounce help circuit?
What do you mean "help".
It's normally just called a "debounce circuit".
It inhibits the circuit from responding to the bounce signals from a mechanical switch.
 

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