I saw some discussion, but it seemed intended for more complicated projects.
I've set up a very simple alarm circuit to monitor an 80mm 25 CFM fan (110VAC) using a Stego air flow monitor switch (500mA 10W), 6V 20mA piezo buzzer and 6V 200mA AC adapter. The Stego switch is normal closed with a threshold air flow 8.2 feet/sec, which this fan just barely exceeds. I'm getting some nuisance alarms due to occasional backdrafting.
I want to introduce delay between switch closing and buzzer buzzing. Fan failure is not an emergency, so adjustment from at least 15 seconds to a few minutes (hours?) would be nice.
Seems to be a job for a variable resistor controlling a capacitor which switches a transistor that shows 6V to the buzzer. Or some kind of 555 timer circuit.
That's the limit of my understanding of circuit design. I can, however, breadboard from a diagram or put together a kit.
BTW, higher CFM fan would exhaust more air than necessary, a waste of heat in winter. And maybe I can learn something along the way here.
I've set up a very simple alarm circuit to monitor an 80mm 25 CFM fan (110VAC) using a Stego air flow monitor switch (500mA 10W), 6V 20mA piezo buzzer and 6V 200mA AC adapter. The Stego switch is normal closed with a threshold air flow 8.2 feet/sec, which this fan just barely exceeds. I'm getting some nuisance alarms due to occasional backdrafting.
I want to introduce delay between switch closing and buzzer buzzing. Fan failure is not an emergency, so adjustment from at least 15 seconds to a few minutes (hours?) would be nice.
Seems to be a job for a variable resistor controlling a capacitor which switches a transistor that shows 6V to the buzzer. Or some kind of 555 timer circuit.
That's the limit of my understanding of circuit design. I can, however, breadboard from a diagram or put together a kit.
BTW, higher CFM fan would exhaust more air than necessary, a waste of heat in winter. And maybe I can learn something along the way here.