cd4013 different than 74hc74


Joined Nov 28, 2009
just a thought...

the 74hc74 doesnt like voltage over 6 volts at Vcc
the 4013 doesnt like to function below 6 volts at supply.

Have you adjusted the supply accordingly?


Joined Apr 20, 2004
The CMOS logic family is characterized for operation from 3 to 15 volts.

I cant see my output in pin 9
That might be because pin 9 is a D input. Look on pin 13(Q2) or 12(Q^2).

Make sure unused inputs are tied high or low as appropriate to prevent oscillations and enable predictable operation. With the SET and RESET inpyts low, Q should follow D with each clock.


Joined Jul 17, 2007
Actually, 4000 series CMOS IC's can function from around 3v to 16v; some slightly higher, some slightly lower.

What are you using for a clock input? CMOS should be OK, but if you're driving a bunch of TTL loads you may have problems.

Do you have an 0.1uF cap across the Vcc/GND pins?

Do you have long interconnecting wires?

Very important: do you have any unused INPUTS connected to either Vcc or GROUND? Particularly, the SET and RESET inputs connected to GROUND?

Oops, Beenthere - pin 9 is Q2.

8 - Q2\
9 - Q2
10 - SET 2
11 - CLOCK 2
12 - DATA 2
13 - RESET 2

Connect 8 to 12
Connect 7, 3, 2 to GND
Connect 14, 13, 10, 4, 1 to Vcc
Connect 0.1uF cap from 7 to 14
Connect clock to 11
Output on 9
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Joined Apr 20, 2004
Het, Gunny, my 1978 National Semi CMOS data book gives pin 9 as the D2 input. My 1991 Motorola CMOS logic databook agrees. Are we talking CD4013 CMOS?


Joined Jul 17, 2007
Het, Gunny
psst... I never got past Sgt... Gunny is two ranks above...;)
my 1978 National Semi CMOS data book gives pin 9 as the D2 input. My 1991 Motorola CMOS logic databook agrees. Are we talking CD4013 CMOS?
Ahh, OK - that's where you got confused.

He was originally using a CD4013B, but tried changing to a 74HC74, and ran into problems. The pinouts for the 74HC74 are completely different from the CD4013B which he figured out, but got bit by the SET and RESET inputs working differently on the 74HC74 than they do in the CD4013B.

I got it backwards in my reply, too. No wonder he had a lousy-looking output.


Joined Feb 24, 2006
HAHA got it working. , the set and reset must be at +5v , not ground level like the 4013

Totally different than the cd4013 .

What kind of stupidity is this to not make it pin compatible and inverted connections lol .

just like this
Do you seriously expect us to believe that 4000 series CMOS and 74HCxx series chips were EVER supposed to be pin and function compatible? Sorry chum, but that was never the idea. 4000 series CMOS was a competitor to 74xx TTL and rearranged the pinouts and functions for what seemed at the time like really good ideas to the original designers at RCA, National, Harris and other early CMOS vendors. You really ought to learn some history before you go throwing stones at your predecessors.

Another piece of obviously useful advice would be to carefully read the datasheet before resorting to hairpulling.


Joined Feb 24, 2006
Heres something frikkin illogical for ya .

Heres what I used to get from my cd4013 when I was pulsing it this way set and reset as shown .

I connect the D,clock ,and Q-bar to ground OR + 5 volts wich is pin 2,3,6 on the 74hc74 , here what I get now with this 74hc74 , total BULLCRAP .

The set positive edge actually ends the Q pulse and the negative edge starts it back up , WTF !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! . The reset just leave a little bump on the high side , it doesnt even register !!

I can't follow what you are doing with the poor chip, but hooking Q-Bar to ground is a definite no-no. How about a schematic to remove the doubt and ambiguity. BTW this chip has been happily chugging along for almost 40 years. Any problems you are having are almost certainly your fault, assuming that your previous misadverntures did not fry the little beastie.


Joined Jul 17, 2007
I have to plead distraction. We have company here, and I was trying to answer your question in-between conversations.

The SET and RESET inputs must be kept high, unless you want to either SET or RESET the output. They must not both be low at the same time.