HELP WITH 4017 RESET

sghioto

Joined Dec 31, 2017
8,634
yes, i admit i was surprised it didnt work
Did you find the problem, bad solder connection or something?
I have the circuit on my breadboard working perfectly.
Additional design improvement.
Leave C1 at 0.1uf and R7 at 100K, this provides a better reset if the 9 volt supply is slow to come up to full voltage.
Install R7 from pin1 to pin15.
Keep C4 and R10
1768073791330.png
 
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sarahMCML

Joined May 11, 2019
697
If the reset still doesn't work I'd suggest replacing the R7 between pins 1 and 15 with diode D2, as in @sghioto's #7 post, and replace the red wire connecting C1 to V+ with another diode, with its anode to V+. This totally decouples the capacitor from the reset circuit after the initial power up reset, but needs power removed to discharge the capacitor.
 

Thread Starter

dave321

Joined Dec 10, 2010
65
hi all,
i tried a new 555monostable one shot i had lying around and believe it or not the circuit now works perfectly !!:). so the on board 555 circuit must have had a problem somewhere.

sghioto i will bear in mind your improvements suggested for the 555 one shot circuit when i have need to make another.
once again your help has helped me succeed, thank you all for your time and knowledge !!!
 

dl324

Joined Mar 30, 2015
18,329
i tried a new 555monostable one shot i had lying around and believe it or not the circuit now works perfectly !!:). so the on board 555 circuit must have had a problem somewhere.
That doesn't explain how the counter was sometimes counting to 8 (and not 9) because it should have been reset by the Q5 output. What are the loads on the transistors? Is the power supply a battery?

Did you put the ICs in sockets? You never know when you'll need to replace one; or want to use it in another circuit.
 

Thread Starter

dave321

Joined Dec 10, 2010
65
That doesn't explain how the counter was sometimes counting to 8 (and not 9) because it should have been reset by the Q5 output. What are the loads on the transistors? Is the power supply a battery?

Did you put the ICs in sockets? You never know when you'll need to replace one; or want to use it in another circuit.
yes the ics are in sockets and yes its a 9v battery.
with the new 555 one shot it works fine and resets as it should after 5 outputs
 

MisterBill2

Joined Jan 23, 2018
27,530
Your problem is that C1 capacitor is too large in the orginal 4017 circuit. Try 10 nF instead of 100 nF.
It is not likely that either the capacitor or the resistor are needed in the reset circuit. CMOS outputs are active both high and low, and so the reset is always connected properly and not floating.
 

eetech00

Joined Jun 8, 2013
4,705
hi,
i need your help again guys......
i have made the attached circuit, which i wanted to reset after the 5th output, so i connectected the reset pin15 to pin 1, but it behaves erratically and outputs up to 8? not 5.
C1 is between pins 15 and 16
(the trigger is a ~200ms pulse from a 555 monostable feeding pin 14)
what have i done wrong ?
1. If R1 is 180k, then C1 needs to be 1uF to generate a 200m pulse.
2. Change the PB circuit to differentiate the signal. This ensures that only 1 pulse will trigger the timer until the PB is released. Like this:

1768452423414.png

Pin 3 would connect to pin 14 of the CD4017.
 
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