Weird 4017 behaviour

[greggles]

hi Audioguru

Yes that is right, when diodes are used they are usually in pairs and act as gates, this is just another method.

Seems to be a lot of conjecture when it comes to the scanner circuits with 4017's i thought this would at least cure the dilema.

No hard feelings Guru and yes your help seems well recieved around here. keep it up, if i can help with anything let me know.
regards Greg

 

[Oxbo Rene]

Well,
What about that one wire up there in the corner, it looks a bit out.......?

 

[Smonjirez]

Hi,

Been a while since I posted something.
I've got the 4017 to work just fine, finally =P. Added 2 bypass capacitors (10 uF and 47 uF) and, well, a 1k resistor from the clock pin of the 555 chip to the capacitor connected to the potentiometer (don't know how to explain it different =P).

So, I got that to work.
Added a 4081 chip for and-gates, also seems to work just fine.
But, when I add my second 4017 chip THAT one starts behaving odd.
Now the clock input from my second 4017 chip comes from the AND-gate from the 4081 chip.

Is this clock output useable or should I also connect this output to the capacitor connected to the potentiometer if you know what I mean?

 

[Smonjirez]

Ok well I double checked the circuit and now both 4017 chips are working fine. One problem. I want my first chip to do the "upwards" movement (i.e. led 1,then 2, then 3 etc) and the second to switch on the same leds, but in backwards movement (i.e. led 8, led 7 etc.). But, when I connect one of the second 4017's pins to one of the other 4017's pins where a LED is attached, that LED won't light up a single time (I find this strange since the 4017's have internal diodes at the output ports). Ofc. both chips don't switch on LED's at the same time.

 

[audioguru]

The CD4017 does not have internal diodes at its outputs. The outputs go high or go low. Connecting two outputs together shorts them.
To make a Knight Rider bunch of LEDs that light back and forth then make a Knight Rider circuit (look for it in Google) that uses diodes in series with the outputs.

 

[Smonjirez]

Yea I noticed just after I posted my last message.
Circuit is working just fine =) I've got my own knight rider lights =D.
Besides, my pot. meter works fine, but the lowest speed is still quite fast and when you set the pot. meter to the "middle-speed" the speed is insane, can't even see them flickering anymore.

Do you know how I can fix it so that my pot. meter changes the speed from very slow to quite fast instead of mid-speed to INSANE-speed?

 

[audioguru]

You did not post your latest schematic.
The value of the timing capacitor affects the speed. Increase it to slow down the speed.

 

[marvel6869]

Your CD4017 is not connected to 0V so it cannot do anything.
I don't see the important supply bypass capacitors.

is there any way to test the 4017 chip if its good or deffective..?

 

[audioguru]

is there any way to test the 4017 chip if its good or deffective..?

Make a simple chaser circuit with a fairly low clock frequency so you can see each output light its LED.

 

[d_6789]

i need help schematic two CD4017 connect, out from Q1 to Q20 !

 

[audioguru]

I have never seen a circuit that cascades two CD4017 ICs to make Q1 to Q20. But most datasheets show a circuit that has 9 outputs on the first IC and 8 outputs on each next IC.