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Electronics => Projects, Designs, and Technical Stuff => Topic started by: Jim-0000 on April 08, 2019, 10:43:15 am

Title: Bistable Flip/Flop circuit second LED required. (Solved).
Post by: Jim-0000 on April 08, 2019, 10:43:15 am

I have this little circuit wired up and operational for indicating the state of a device which will be either activated or not.

http://www.circuitbasics.com/555-timer-basics-bistable-mode/ (http://www.circuitbasics.com/555-timer-basics-bistable-mode/)

It is working and doing part of the task required.
It shows the LED on until it is triggered via a 4N25 opto coupler.
All good.
Except that the user would like a (different colour)  light on when the 555 flip flop was in the other (or second) state.
Can someone advise where a second LED should be wired into this circuit to indicate the alternate stable state please?

Jim.

Title: Re: Bistable Flip/Flop circuit second LED required.
Post by: Zero999 on April 08, 2019, 02:03:32 pm

Connect another LED between pin 3 and the positive power supply, via a suitable current limiting resistor.

Title: Re: Bistable Flip/Flop circuit second LED required.
Post by: Jim-0000 on April 08, 2019, 09:17:34 pm

Thanks for the prompt reply. I will give it a try this morning.

Edit:

I just tried it as suggested by zero and it all works fine!
I'll mark this thread as solved.