CMOS 4013 Toggling Issue

Thread Starter

Robin Mitchell

Joined Oct 25, 2009
819
Hi all,

So I am making that Z80 Computer (ZBM), and I am having issues with these 4013 chips. Firstly, they are from china and I have tried two different chips but the same problem is still happening.

Simply put:

I have a toggle made from the flops (connecting /Q to ), so when the clock line is pulsed the flop toggles. Now this works if I use a wire directly from the clock line and connect it to the power but if I use a tactile switch it will happily turn on but not toggle back.

Now get this... If I use a supply of less than 3V (currently using 5V), the tactile switch works perfectly every time! That makes no sense at all to me:S! Why would it work only at a lower voltage when these devices are rated up to 15V!

I measured the voltages on the pin and nothing unusual is showing up :(

I do have de-bouncing circuitry
All unused inputs are pulled to ground

For now I am digging around for an "official" 4013 as a reference incase these chips are rubbish.
 

Thread Starter

Robin Mitchell

Joined Oct 25, 2009
819
@crutschow

I would have posted the schematic if this new chip did not work. I have a feeling that it is either some kind of minor voltage breakdown where the higher voltage is interfering with the silicon and causing mayhem.

Lesson Learned :(
 

Thread Starter

Robin Mitchell

Joined Oct 25, 2009
819
Got them on Ebay and they are "supposedly" TI. I know that they are not but I am irritated that they work on low voltages but not at 5V which my whole system runs on!
Any who just bought some more from a UK supplier so that fixes that!

I am requesting a refund from the seller and claiming they are faulty and forgeries.
 

Thread Starter

Robin Mitchell

Joined Oct 25, 2009
819
What I cant understand is that it works when you take a wire and connect the clock to power but if you connect it through a switch then it suddenly does not work. And both attempts use the de-bouncer which is just a capacitor and resistor in parallel. It works flawlessly with a REAL 4013 but these chips, im going to have to throw 100 of these things away :(
 

Thread Starter

Robin Mitchell

Joined Oct 25, 2009
819
Here are two photos I took with my microscope.
The 4017 Chip is an official TI part where the 4013 is the fake chinese part.
FakePart.png RealPart.png
  • Font is bigger
  • Logo is wrong
  • Pins are too wide
  • E4 is in the wrong place
  • The notch is too big (not shown in the picture)
  • The epoxy colour is wrong
 
Top