Hi - maybe being dumb - I have a 4017 chasing light circuit with a 555 clock signal that works fine with a HEF4017BP counter, but when I swap for a HCF4017BE chip it just lights the first LED - I got a load of the HCF4017BE chips to make these with my scout group, but they dont seem to work like my prototype! Is there any difference in how I should treat them? the HCF4017BE was about half the price of the other...
Thanks for any suggestions!
Alan

 

You really need to show your circuit diagram. A photo of your circuit layout might also reveal some wiring or construction issues.

What is the part number of the 555 timer?
I would suggest using a CMOS 555 such as LMC555 or TLC555.

Put a 0.1μF capacitor across Vcc and GND at the 555 chip.
AND put a 10μF electrolytic capacitor across Vcc and GND.

 

To measure the voltage of the first output of CD4017 with no load, adding the load and measure again, to see what's difference between two conditions, comparing them how many voltages drop down?

Changing the CD4017 and to do the measuring as above.

 

Last suggestion worked! Changed the chip and found that 2 of 9 ICs were bad.

The circuit was a simple 555 astable circuit to give a clock signal to the 4017 which then cycled forwards and back along a line of 6 LEDs. I skipped the capacitor on pin 5 of the 555 and didn't bother putting reset pin 4 high. I didn't protect any of the LEDs with resistors and didn't smooth the inputs to the 4017 with a capacitor between Vdd pin 16 and gnd on the 4017. It was all squeezed on the smallest breadboard with risks of the diodes from 4017 to the LEDs shorting etc etc Nevertheless, when I swapped a new (good) IC in, it all worked fine. No issue with the letters after HFC4017 BP and BE do the same. Rapid's HCF4017BEY is less than half the price that they have a HEF4017BP - anyone know what the difference is?

To test I laid it all out on a big breadboard with smoothing capacitors and protective resistors etc and found same symptoms and then changed the IC which then made it all work as designed. Stripping back to minimal circuit gave no problems with the good ICs...

Are teh 4017s susceptible to damage? the 555 chip seems to take anything put into any pin and then work fine when its wired correctly afterwards, but the two ICs that didn't work were both ones that the scouts had played with first... Anyway - thanks for suggestions - just needed telling to sit down and check it all out properly...

 

Yes, if scouts were running and jumping and fooling around as scouts usually do, they will zap 4017s with ESD (electro-static discharge) really fast.

You need to pay attention to ESD prevention rules.

 

I guess so - I used to tell them to be careful but have not had a prob with things for ages! Maybe the scout hut floor is particularly bad? (my kitchen quarry tiles are where we've done most of the recent stuff in an activity club rather than in a troop night... Are the 4017s very sensitive?

 

You didn't show the voltage of the all output when they added the LED and not.

You better connecting the all output of CD4017 together and in series with a limiting resistor, because some output of CD4017 that their current not so high, when you added the LED to GND directly with no resistor, it could drawn too much current and make the output voltage drop down, it will also stop the function of CD4017.

 

With the good chip I get 1.5V on the outs connected and about twice that when disconnected (outputs cycling with the clock signal). With the bad chip it gave 9v on output one and 0 on the rest when disconnected and tripped the voltage limit when I connected the LEDs ... Bad things happened to the chip I guess...
I've attached a pic! Little board on left is the production board and bigger board on left has it spread out a bit more...

 

I can't see your circuit.

 

tried and failed to load picture but then read FAQ - see image a couple of posts down

 

Hello,

We can not see your picture as it is password protected (you have to sign-in to see it).

Please upload the picture to this forum.
In the FAQ is given how to do this:
Attachments and Images

Bertus

 

Sorry - I'll delete failed picture uploads and try here.
Photo shows scout breadboard on left and a spread out one when I was testing stuff on the right...

Actually, I guess I could skip all the diodes and just use (coated) wire and avoid all the issues with shorts between the diodes...

 

Hello,

I see a lot of blank wires ( the ones on the diodes ) that might be touching each other.
If outputs of the 4017 are shorted by these wires, the voltages on the outputs will not be correct.

Bertus

 

Yep - all the diodes didn't really help and it works just fine with coated wire instead (why am I using diodes to protect the LEDs?). You can see the finished product here http://http://boreattonscouts.blogspot.co.uk/2013/10/chips.html

 

Hello,

You might be interested in the following thread:
Project: Knight Rider style sweeping light.

Bertus