Maker Pro
Maker Pro

555 to CD4013: Direct Connection?

The New Guy

Jun 6, 2017
8
Joined
Jun 6, 2017
Messages
8
Hello All,

Attached is a schematic for a frequency divider circuit, that I want to build. I found it on the internet. I see that there is no resistor between 555 Pin 3 (Out), and CD4013 Pin 3 (Clock). Can this be done?

Thanks
 

Attachments

  • 555_4013_1.png
    555_4013_1.png
    34.9 KB · Views: 17

bertus

Moderator
Nov 8, 2019
3,307
Joined
Nov 8, 2019
Messages
3,307
Hello,

When the NE555 and CD4013 are on the same powersupply, that should be fine.

Bertus
 

Harald Kapp

Moderator
Moderator
Nov 17, 2011
13,700
Joined
Nov 17, 2011
Messages
13,700
I agree with Bertus. What makes you think there should be a resistor?
 

Audioguru

Sep 24, 2016
3,656
Joined
Sep 24, 2016
Messages
3,656
Why is the CD4013 not connected to the power supply?
Why is the +5V missing a decoupling capacitor?
Why are you using an old 555 instead of a new Cmos 555 in the Cmos CD4013 counter circuit?
 

Harald Kapp

Moderator
Moderator
Nov 17, 2011
13,700
Joined
Nov 17, 2011
Messages
13,700
Why is the CD4013 not connected to the power supply?
It definitely needs to be connected to +5 V and GND. However, this may simply be a typical omission you will find in many schematics. If only one supply voltage is present, it s often assumed that all ICs are connected to that voltage. Doesn't make it easier for amateurs, though :(
Why is the +5V missing a decoupling capacitor?
Possibly because this is a not too well designed hobby circuit? Who knows. I totally agree, better yet, each chip (IC1, IC2) should have its own decoupling capacitor, right next to the supply pins, connections to the IC as short as possible.
Why are you using an old 555 instead of a new Cmos 555
Where do you take this information from? The schematic says only "IC1 555).
Of course, it is highly recommendable to use the modern CMOS variant.
 

Audioguru

Sep 24, 2016
3,656
Joined
Sep 24, 2016
Messages
3,656
The thread starter's first post here was about a "555". Maybe he does not know about its antique problems and does not know about a Cmos 555.
Intersil shows than an old 555 has a 400mA (!) shoot-through current each time it switches and the datasheet for an old 555 says that its decoupling capacitors are mandatory to protect associated circuitry. The Cmos 555 has no huge shoot through current.
 

Attachments

  • 555 current spike.PNG
    555 current spike.PNG
    12.6 KB · Views: 1
Top