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I need to toggle a MOSFET after I hold a button for 3 seconds. Here is my circuit:

enter image description here

I have a JK flip-flop for the toggle function. When the clock pin of the JK flip-flop goes high to low, output of the flip-flop toggles. There is no problem here. The 555 timer gives a single shot signal after holding the button for 3 seconds. The problem is that when I press the button, the JK flip-flop toggles instantly though even 555 timer doesn't give an output.

My theory is that when the button is off, the 555 timer output is a floating around 0.150 volt. When I press the button, the output of the 555 becomes 0 volt, no longer floating and it becomes ground. The JK flip-flop therefore thinks this is a clock down and toggles the output.

How can I fix this?

JRE
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Alican Uçar
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  • Is this supposed to be a hold-for-3-seconds to turn off device kind of thing? Or something else? – periblepsis Nov 07 '23 at 06:42
  • Yes, i want to turn on and turn off when i hold the button 3 seconds or more. – Alican Uçar Nov 07 '23 at 07:07
  • That's probably a sot23-6 MCU then. Cheap. Easy to use. Easy to adapt, where needed. But I did find this on this site if 555s are to be used. – periblepsis Nov 07 '23 at 07:25
  • You're switching the Vcc to the 555. Maybe try an RC on the /RESET input. But I don't like this circuit much. – Spehro Pefhany Nov 07 '23 at 07:29
  • i don't have microchip programmer, so it is not kinda viable solution. @SpehroPefhany maybe i can keep vcc of 555 timer high all the time and connect only the reset pin (with pull down) after button i will try that. – Alican Uçar Nov 07 '23 at 09:10
  • A bipolar 555 draws quite a bit of current just sitting there, so it’s inappropriate for a battery-powered device. Otherwise it might be okay. – Spehro Pefhany Nov 07 '23 at 12:46

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