addind dry contact output to an airflow alarm 1

[mcgreen]

This is for an airflow alarm. I designed this simple airflow alarm and all is working well. When the airflow is above the setpoint a green LED is on. When it falls below the setpoint a red LED comes on. If the airflow falls below the setpoint for more than five seconds a buzzer comes on. When a button is pressed the buzzer is silenced. I'm trying to add a dry contact output to my alarm. If I just used the buzzer output to drive the relay it would go off if the alarm was silenced. I would like for the relay to stay activated until the buzzer is silenced and the airflow goes above the setpoint. I've attached a better explanation.

 

[MikeHalloran]

Drive the relay from the green LED circuit.


Mike Halloran
Pembroke Pines, FL, USA

 

[mcgreen]

There is a problem with only using the green LED circuit. When the buzzer comes on it stays on, even if the green LED comes back on. It must be silenced by pressing the push-button. The green and red LEDs can "flicker" back and forth depending on what the airflow is doing. I only want the alarm to go off when the red LED stays on for more than 5 seconds. If it does, it stays on until silenced, even if the green LED comes back on.

 

[Skogsgurra]

I suggest that you contact an EE to have this device designed.

It has been said so many times that this is EngTips, not WeDesignForYou. There is a difference between tip and full service.

Gunnar Englund

http://www.gke.org

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