Hello Team.

I have a very simple circuit.

I1 is a smoke detector - NC

I2 is a momentary push button for reset

Q1 supplys power to external item

Q2 supplys a fan and a green light

Q3 is a sounder

Q4 is a red light.

Normal operation - q1 & q2 are going.

Smoke is detected, q1 & q2 is switched off and q3 & q4 are on.

Smoke clears q3 stays on until I2 is pressed then it returns to the beginning.

Issue is, if the smoke detector I1 goes off again, it starts cycling through the whole series without needing reset I2 to be pressed.

Is there a way I can stop I1 from doing this while also being able to have the ability to turn on q3 & q4 is smoke is detected again?

Any thoughts and ideas would be appreciated.

Thank you

Hello Ixo65,  thank you for that suggestion.

I cannot have a timer in the circuit as if smoke appears then Q1 & Q2 need to turn off & Q3 & Q4 need to turn on. 

When smoke is cleared and I1 turns back on, then Q3 needs needs to turn off.

When I2 (reset) is pressed then Q4 turns off, Q3 is still off, (its a very loud sounder) and Q1 & Q2 come back on.

My main issue with my original design (apart from feeling like I am over complicating it) is that if you continuously press I1 it cycles through all the stages.  eg Q1&Q2 on, Q3&Q4 on, Q4 on, all off, Q1&Q2 on...

in a perfect world until the reset I2 was pressed, the only things I would want on would be Q3 & Q4 

Thank you

Hello rick_wright198,

Do you mean it like this?

Greetings Ella_68

Hello Ella_68,  Thank you for that suggestion.  Unfortunately not quite.

What I currently have is...

I1 - Normally closed - system runs normally. Q1 & Q2 running.

I1 - Smoke Detected, circuit opens... Q3 & Q4 running. 

I1 - Smoke Clears Q3 turns off, Q4 stays going.

I2 - Reset pressed - System returns to normal.

Main issue is if the smoke detector on I1 goes off again before the reset switch is pressed, I1 will reset the system back to the beginning.  If I1 continuously detects smoke and then clears it will keep resetting without needing I2 to be pressed.  

The problem with your program is the use of the impulse relay B002 (also B005). Use simple RS modules.

One question for understanding. The sounder (Q3) should be active as long as the smoke detector (I1) emits a low signal ?

Ella_68

(translated by google)

Thank you both of you.  You both gave me great ideas.

the final solution was...

Thank you for your assistance.