Bad 4017 or Bad circuit?

[Zebo]

I am new to the 4017 so I tried the most basic circuit I could find. See photo attached.
I use 4.5V with a resistor to protect the LED.
Pin connections:
4 (output 3) to the LED via a resistor
8 = 0V
13 (Latch enable) to 0V
14 (Clock) to button to pulse 4.5V from the + rail
16 to +4.5V
Pulsing the switch never turns on the LED.
I also tried a Re-set from pin 4 (output 3) and the LED to pin 2 (output 2), no improvement.
If I move the LED from 4 (output 3) to 3 (output 1) then I get a continuous LED on. It stays on even if I pulse 4.5V to pin 13 (clock).
I have tried 3 different chips.
Can anyone give me some clues?
B.T.W. there seems to be a lot of stray energy around as moving my hand over the board produces flickering which makes me believe the chip does work. I turned off all the 50Hz power in the vicinity and the flickering stopped.

I sure hope someone can help me with this.

 

[crutschow]

Do you have all the unused pins tied to ground or the plus rail, which is rule number one when using CMOS? Any floating nodes in CMOS will cause erratic behavior. That's likely what cause the flickering when you waved your hand.

 

[ronv]

Try adding a resistor (maybe 10k or so) from pin 14 to ground. The clock is "floating" when the switch is open.

 

[MRCecil]

First, the negative rail of your breadboard shows no return to the supply (pin 8). Is the return out of the picture? Second, the reset (pin 15) is floating. For full count, it should be tied to the neg. rail, or it should be tied to one of the outputs to count to that point then reset. Third, the switch can cause multiple triggers and should be debounced for predictable results. Lastly, is that resistor a 220K? If so, you'll need to lower the resistance to a level based on the source current limitations for the 4017 at Vdd.

 

[Zebo]

Do you have all the unused pins tied to ground or the plus rail, which is rule number one when using CMOS? Any floating nodes in CMOS will cause erratic behavior. That's likely what cause the flickering when you waved your hand.

All outputs are left open except 4 which goes to the LED. 8 to ground, 12 open, 13 to ground (I see in the photo the jumper to 13/gnd is missing, now put back), 14 to the switch wich is open. Should all open outputs be connected and if yes to which rail? 15 is tied to gnd.

 

[Zebo]

Try adding a resistor (maybe 10k or so) from pin 14 to ground. The clock is "floating" when the switch is open.

With the 10K resistor the LED does not flicker any more, but now I guess it is contact bounce because it is difficult to get it to stop on output 4. I see it flicker when it goes past. I will try the pulse from the GPS receiver which will drive my circuit eventually. Thanks for this reply.

 

[Zebo]

First, the negative rail of your breadboard shows no return to the supply (pin 8). Is the return out of the picture? Second, the reset (pin 15) is floating. For full count, it should be tied to the neg. rail, or it should be tied to one of the outputs to count to that point then reset. Third, the switch can cause multiple triggers and should be debounced for predictable results. Lastly, is that resistor a 220K? If so, you'll need to lower the resistance to a level based on the source current limitations for the 4017 at Vdd.

Negative supply is off the photo. It is ground to 8 and +Vs to 16.
Sorry, I had pin 15 to ground, somehow I lost the jumper for the photo. It makes no difference with the jumper fitted. Yes, I am aware of switch bounce, but with the LED on it does not turn off when I press the switch, so it is not counting.

Fitting a 10K resister as suggested by ronv it seems to count. I now have to work on teh bounce. Thanks for your help.

 

[DemonicSandwich]

First, the negative rail of your breadboard shows no return to the supply (pin 8). Is the return out of the picture? Second, the reset (pin 15) is floating. For full count, it should be tied to the neg. rail, or it should be tied to one of the outputs to count to that point then reset. Third, the switch can cause multiple triggers and should be debounced for predictable results. Lastly, is that resistor a 220K? If so, you'll need to lower the resistance to a level based on the source current limitations for the 4017 at Vdd.

Looks more like 110K which is still vastly too high and still the main reason for the LED not lighting.

 

[Boncuk]

Hi,

Pins13(CLOCK INHIBIT) and 15(RESET) must be connected to ground to enable count. Pin14(CLK) requires a pull down resistor of 10KΩ.

(Now pin13 is tied to VDD and pin15 is floating)

with R2 being 820Ω the max LED forward current will be ~7mA at 9V - so the LED will light up pretty dim.

For a bright LED connect T1 as shown in the second schematic.

Boncuk