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JK flip flop help

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intensenex

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I am really having trouble with my dual JK flip flop 4027bp
I have all my connections right and inspite of that i get output as high from all pins. And not only that, at times the voltage is swaying from 3v to 5v. (Battery is a little down so i am getting 5V)


here is my circuit diagram
**broken link removed**

I have built the same circuit and the output never goes down upon playing with the switch infact i even get output from the second flip flop pin on the left side of the IC. Also sometimes output goes around 10V wen i connect the Vcc back again.

i have hopelessly give up for now. i think my IC is messed up.
 
I am really having trouble with my dual JK flip flop 4027bp
I have all my connections right and inspite of that i get output as high from all pins. And not only that, at times the voltage is swaying from 3v to 5v. (Battery is a little down so i am getting 5V)


here is my circuit diagram
**broken link removed**

I have built the same circuit and the output never goes down upon playing with the switch infact i even get output from the second flip flop pin on the left side of the IC. Also sometimes output goes around 10V wen i connect the Vcc back again.

i have hopelessly give up for now. i think my IC is messed up.

hi,
The 4027 is CMOS technology, you must connect the Set and Reset pins.

I am trying to attach a drawing without success.! sorry about that. Connect the Set and Reset to 0V.

AAesp01..gif
 
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Also, connect all unused inputs, including those on the unused FF, to ground or Vcc. Vss must be connected to ground.
 
Thx everyone for ur quick reply, i connected all unused pins (including the left side unused flip flop pins) to ground including Vss and all used pins(only J,K and Clock,VDD)) to positive 9V, i get a glimmer of hope. I see that my output compliment is showing no signs of voltage and my true output is showing voltage but wen i flick the switch connected to J,K and C with VDD i don't get on/off. But wat i did notice is wen i check the true output to have 9V (using 9V on VDD) and flick the switch it doesn't go off. But i wen i check the compliment output that shows no voltage and wen i flick the switch it goes ON (shows 9V). I check true output then which now shows no sign of voltage and flick the switch again and i see 9V but again doesn't go off wen i flick it again.

DON'T understand wat's going on there but i do see 9V on compliment output on the left side of my CMOS.( i am using right side)
 
K i just found out this. I connected my Jk flip flop clock to my 555 timer give output of 6.5 Hz and i see my true output changing according to that Hz but sadly shows no signs of voltage rise wen i change frequency to 0.7 Hz.
 
To make the FF toggle (divide by 2), connect the clock input to the 555 output (pin 3), and connect the J and K inputs on the FF you are using to Vcc. Use a fresh battery.
 
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Connect to Vcc??????? i don't see any pin for Vcc. Btw i don't care much for using clock input to make it work at this moment i jus want my JK flip flop to simply work i.e on/off using a switch. i grounded evrything except VDD,J1,K1, clock and Q2 and its compliment Q2. ALso i don;t see how fresh battery might change things
 
It's not a pin. You mentioned vcc in post #1, so I assumed you knew it is the positive battery terminal.
What I meant was, connect J and K to the positive battery terminal.
You said that the nominal battery voltage is 9V, but you are seeing 3V, and 5V, and 10V. This implies that battery impedance is very high. Flip-flops (and most other ICs) don't work well with high impedance supplies. That's why I suggested a fresh battery.
I suggest you to use the 555 to start out, because a switch needs to be debounced. That requires another IC. After you get your 4027 working, we can show you how to debounce your switch.
 
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Oh forgive my last reply, i am already frustrated for not getting it to work. So yea in my previous reply i already said that my 4027 flip flop seems to be working wen i connect it with my 555 timer at 6.5 Hz but not 1 Hz but then i noticed from my buzzer that my frequency has lowered after i connected to my 4027. Btw any suggestion to fix that will be appreciated. Anyway since flipflop works with my 555 timer i guess we can move to debouncing my switch. I don't really know what that means. Also can you explain the term battery impedence. Do u mean internetal resistance by that cuz correct me if i am wrong but i think impedence is just resistance in AC circuit.
 
Oh and i gotta wait till tomorrow to get a fresh 9V battery so yup i tried it with my downed 9V battery and my flip flop with 555 timer runs fine. (gives 5V output). I have been dealing with some kinda electrical magic, evreytime i go near that switch the voltage goes down and goes up wen its down and yea its not perodic. ( i tried waiting for a min and going near it again). Sometimes wen i make a loud noise it changes again. So yea u can guess there's something wrong with my CMOS, i even tried manually touching wires instead of switch still no difference.
 
Oh forgive my last reply, i am already frustrated for not getting it to work. So yea in my previous reply i already said that my 4027 flip flop seems to be working wen i connect it with my 555 timer at 6.5 Hz but not 1 Hz but then i noticed from my buzzer that my frequency has lowered after i connected to my 4027. Btw any suggestion to fix that will be appreciated. Anyway since flipflop works with my 555 timer i guess we can move to debouncing my switch. I don't really know what that means. Also can you explain the term battery impedence. Do u mean internetal resistance by that cuz correct me if i am wrong but i think impedence is just resistance in AC circuit.
Yes, when I said battery impedance, I did mean internal resistance. Either term is correct. Resistance is a type of impedance.
Please post a schematic of what you have working with the 555, then we can get on to a switch debouncer. Bounce is a characteristic of most mechanical switches. The contacts will close and open multiple times within a few milliseconds. If you don't clean this up, each bounce will clock the FF. Google "switch debouncing".
 
THere...

**broken link removed**

The 1K with LED in output of 4027, i have it replaced by my buzzer. I was aware of switch debouncing so i manually tried touching wires (a simple tap) and still no success. U missed my other reply just above urs. I think it might give u more essential detail. Also can u suggest how to get back the same frequency of my 555 timer from my 4027 ? If nuthing can be done about it can u give out any equation to determine wat frequency will my 4027 ultimately output.
 
Touching wires will cause more bounce than a switch.
The reason you are having problems with proximity of your hand is that CMOS inputs have extremely high impedance (essentially infinite resistance in parallel with a few picofarads of capacitance). Your clock input needs a pulldown resistor to ground when the switch is open, to keep it from floating. 100kohms will work, but you still need a debouncer between the switch and the clock input. If your debouncer is another IC, like a CD40106 Schmitt trigger with appropriate filtering on the input, that moves the location of the pulldown to the input of the Schmitt trigger.
Why would you want to get the clock input frequency to appear on the FF output? FFs are good for several things, but a buffer is not the most efficient use of their capabilities. The circuit I suggested (J and K to +V) will result in the input frequency being divided by two.
 
ok i just tried ur suggestion for pull down resistor (100k) to ground. The circuit describes below ( pull down resistor marked in red)
**broken link removed**

I bought a new JK FF MC14027bcp and a fresh 9V battery and the voltage swaying had stopped but now continuing even with pull down resistor and 555 timer as debouncer. I forgot to buy CD40106 Schmitt today, any alternate method ? I did buy a lotta and and or gates and my beloved 4017, will any of them do for a debouncer ? I just wanted to get the clock input frequency to appear on the FF output to see my 555 timer worked along with my FF but yea i certainly won't use it as a buffer.

I have been wondering, i saw ppl on youtube with thier JK flip flop (not sure if 4027) and one guy had it workin with 5 to 6 connections from its IC. I just don't understand y am i having so much problems with it.
 
You don't need the pulldown on the clock input. The 555 prevents it from floating. As I said twice before, tie J and K to +V, and the FF output should toggle (divide 555 frequency by 2). You will only need the pulldown on a switch to +V, which is when you do the debouncer so you can use a switch for the clock input. You need a schematic for a debouncer. If you can't find one (search), I can provide one.
Do not tie the unused outputs to either rail. Leave them disconnected.
 
i got confused over "Do not tie the unused outputs to either rail. Leave them disconnected" i thought u said put them all to ground but then again i am assuming cuz of pulldown resistor i don;t have to. And lol i am putting JK to +V i even show that in my pic (except for J2, K2, but then again i am connecting them to +V along with Clock2) and yea i would appreciate if u can draw a debouncer circuit for my circuit along with pull down. And yea i thought pulldown resistoris connected to ground and pullup to Vcc, (correct me on that). Btw i put a pulldown from clock input since 555 timer output is basically my switch so and, correct me if i am wrong, 555 timer like u said is cud work as a debouncer so i thought pulldown resistor should be connected to that. So which is again y i am requesting u a debouncer circuit. I think if it wud be better if u edited my circuit pic and add debouncer there.
 
i got confused over "Do not tie the unused outputs to either rail. Leave them disconnected" i thought u said put them all to ground but then again i am assuming cuz of pulldown resistor i don;t have to. And lol i am putting JK to +V i even show that in my pic (except for J2, K2, but then again i am connecting them to +V along with Clock2) and yea i would appreciate if u can draw a debouncer circuit for my circuit along with pull down. And yea i thought pulldown resistoris connected to ground and pullup to Vcc, (correct me on that). Btw i put a pulldown from clock input since 555 timer output is basically my switch so and, correct me if i am wrong, 555 timer like u said is cud work as a debouncer so i thought pulldown resistor should be connected to that. So which is again y i am requesting u a debouncer circuit. I think if it wud be better if u edited my circuit pic and add debouncer there.
Here's what I said:
Also, connect all unused inputs, including those on the unused FF, to ground or Vcc. Vss must be connected to ground.
Note that I did not say anything about outputs.
Here's a circuit that will cause the output to change state every time the switch is pushed.
 

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YYYYYYYYYYYYYYYYYYYYYYYYYYYAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY !!!!!!!!!

THank You so much u eased my pain IT FINALLY WORKS FLAWlessly

but i only used the debouncer switch to make it work

Sir Roff now u gotta explain how does this debouncer really work and plz provide some equations to calculate R1 and Capacitance. The de-bouncer circuit u made, is this the only configuration or there r plenty others?
 
K i am having problems with 4017Bp now. I connected all data to Vcc along with MR. and i only get output from O4 only. I even connected the clock to my new de-bounced 555 output and its still not working. i am trying out the below connection...

**broken link removed**
 
WHooops Nvm i got my 4017 working. Ignore my last message completely. infact i was even lookin at the wrong datasheet , i was looking at 40174bp. That debouncer switch is working wonders for me. THx again
 
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