4013 IC Question

[psecody]

Ok I asked this same question earlier but has gotten no responses and I figure its because the title suggests that I want help on homework or someone to tell me a project when actually I was just having trouble with this IC. All I'm wanting to know is whats wrong with my circuit. It should work but I just can't get it to. When you connect the battery the led lights up then once you push the button the led goes out but then its supposed to light the led back up when tou press the button giving it another clock but it doesn't it just stays off. Can someone tell me what I'm doing wrong because I for the life of me can't figure it out and its driving me absolutely crazy. Thanks

 

[dinesh.s]

Did you take care of debouncing??

 

[psecody]

could you explain this debouncing please? I've heard it mentioned but no I haven't done it if it isn't in that schematic because that circuit in the schematic is the exact one I've been designing.

 

[dinesh.s]

When you press the switch the contact is not made, before the contact being made it would generate lot of glitches, which would act as clock for u r d-f/f. if u think u pressing it once but actuall many clock pulse is given, so u dont get the expected output.

Then tell what sort of output u r getting.

 

[psecody]

ok using the circuit I just showed in that pic when i plug it to a battery the led lights up then when I press the button the led goes off then thats it. I can keep pushing the button till I'm blue in the face after the first time and the led won't re light.

 

[dinesh.s]

Cau u try using a pullup resistor and a capacitor to ground in pin 11

 

[ljcox]

ok using the circuit I just showed in that pic when i plug it to a battery the led lights up then when I press the button the led goes off then thats it. I can keep pushing the button till I'm blue in the face after the first time and the led won't re light.

The reason is that there is no change when you press the button. So you need a pull down resistor between pins 11 and 8.

Then you will toggle the FF in a random manner due to contact bounce.

I suggest you search this forum for "contact bounce" There have been plenty of posts on it in the past.

 

[ericgibbs]

hi,
the 4013 is a cmos device, that is, the impedance of an input pin is very high.
From your diagram pin 11, clk2 input, is floating, any electrical noise will be
picked up on this pin and could switch the device into an unexpected state.

Connect a 4k7 from pin 11 to the 0v line, in parallel with the 4k7 add a
0.22mf capacitor and from your push switch put a 470R resistor in series with
the switch and pin 11. [ a simple debounce r/c filter] . If your switch is of
a poor quality you may have to increase the 0.22mF to say 1mF.
Place these extra components as close as possible to the 4013. keep the
wires as short as possible.

This type of 4013/cct is very noise prone. Have a look at the one posted
recently that uses two invertors in series, its a proven method.

If you need a sketch let me know

Important: never leave cmos device input pins floating, your circuits will do strange
things ie; work one minute not the next. Also they could be damage by ESD
electro static discharge from you or your equipment.
Tie them directly to 0v or to +5v via a 10K resistor.

Regards
EricG

 

[dinesh.s]

I agree with ericgibbs....

 

[ericgibbs]

hi
redraw with added components

EricG

 

[eblc1388]

Tie them directly to 0v or to +5v via a 10K resistor.

Why not directly instead of using a 10K resistor?

 

[ericgibbs]

hi,
From practical experience, I have seen cmos inputs fail when connected directly to the supply lines.
Quite often they fail in a short circuit mode. Possibly due to very fast voltage transients on the power lines taking out the internal clamps.
Problem is, its usually too late to determine the cause of the failure.
For the price of a small resistor is just not worth having the device fail in service and make the equipment unserviceable.

Regards
EricG

I would be interested to hear if other engineers have experienced this problem.

 

[dinesh.s]

Even i had experienced it. it is not too good to charge a capacitor with heavy current. COMS i/p are nothing but a capacitor, when we attempt to charge it with heavy current without a current limiting resistor the FET's fail, inshort the gates fail.

 

[psecody]

Thanks everyone for the help I reallyappreciate it. I'll have to try it when I can get to my board next. But one more question ericgibbs: when you are saying mf are you saying micro farads? Just making sure because I've never seen it abbreviated that way. Thanks again

 

[ericgibbs]

hi,
yes its microfarads. mF, I should have used uF, which of course is still not the
correct notation. I havn't got the micro symbol on my keyboard.

Sorry for any confusion.

Regards
EricG

 

[AllVol]

I may be wrong, but I think poster is trying to accomplish something with this circuit the Dual-D Flip Flop 4013 is not capable of doing in this configuration. As I understand it, he is trying to perform a counting function; however, in this configuration, repeated manual clock pulses via the switch will accomplish nothing more than a blue face, since the D FF is latched on NOT Q output in whatever state the chip is in on power-up. While the data sheet for the 4013 does indicate connecting the NOT Q to D input will provide a counting situation, it is my experience, using a comparable 74LS74 chip, that the NOT Q output of FF1 is to be connected to D input of FF 2 to accomplish toggle or 2-bit count.

Just sharing my experience.

AllVol

 

[ljcox]

hi,
yes its microfarads. mF, I should have used uF, which of course is still not the
correct notation. I havn't got the micro symbol on my keyboard.

As Nigel pointed out to me recently, if you go to the User CP you will find edit options. The second option allows the following symbols (under the smiles)

hm: :mu: :delta: :ltoet: :gtoet:

 

[psecody]

the only function I'm wanting it to perform is a simple toggle of
while Q=1 NotQ=0
and
while Q=0 NotQ=1
I just couldn't get it to change back to Q=1 after the first time.

 

[dinesh.s]

Can try changing the value of 470ohm to 20ohm. be it helps.

 

[psecody]

that doesn't do a thing but send to much power to the led