Air actuated switches

[Barry_L]

I am working on a project that involves vaping I am looking to build something that will require the use a small air actuated switch so something that will turn something on a soon as air passes through it. Any ideas?

 

[KMoffett]

"small air actuated switch"
How small?
What voltage and current switch?
Maximum price?

Ken

 

[Barry_L]

"small air actuated switch"
How small?
What voltage and current switch?
Maximum price?

Ken

Small enough to fit in small tube about twice the size of a straw. The switch just needs to turn on a chip that controls the Vape mod its self. Price.... For prototype 10 bucks. At bulk $1

 

[Harald Kapp]

For one you can use a barometric pressure sensor. It will not detect the flow of air but the change in air pressure which is imho suitable for your application.

Or use a fork sensor (like e.g. this one) and add a small flap that is outside the sensor's light path when no air flows, buit is drawn into the sensor's light path by the flow of air, thus interrupting the ligt path and giving a sensor signal.

 

[KMoffett]

Berry,

Must the switch maintain a closed contact while there is an increased negative pressure/flow or can it be a momentary pulse closure?

Ken

 

[duke37]

Consider a thermistor with a suitable circuit.

 

[Bluejets]

Consider a thermistor with a suitable circuit.

Op is looking at changes in air flow

 

[duke37]

Op is looking at changes in air flow

Yes, he is wanting to detect flow. Heated thermistors will change temperature and therefore resistance with flow. I used such a device to measure wind speeds on a vehicle close to the brakes. It became known as the bee catcher.

Variation in ambient temperature may cause problems.

 

[KMoffett]

A thermistor Wheatstone bridge with two in the flow and two isolated works, and deals well with ambient. But needs to be powered and amplified.

Ken

 

[BobK]

How fast a response would a thermistor give? If he want to turn on the heater only when you inhale, the response has to be pretty quick, not seconds.

Bob

 

[KMoffett]

Bob,

Tiny thermistors can respond in fractions of a second. That said. since the Wheatstone bridge would be quiescent at ambient, sucking in ambient air would do nothing. The bridge would have to be powered to self-heat two of the thermistors, so ambient air would cool them and change the bridge output. But this seems to be getting too complex and require more power that some type of mechanical on/off device.

Ken

 

[Barry_L]

For one you can use a barometric pressure sensor. It will not detect the flow of air but the change in air pressure which is imho suitable for your application.

Or use a fork sensor (like e.g. this one) and add a small flap that is outside the sensor's light path when no air flows, buit is drawn into the sensor's light path by the flow of air, thus interrupting the ligt path and giving a sensor signal.

Berry,

Must the switch maintain a closed contact while there is an increased negative pressure/flow or can it be a momentary pulse closure?

Ken

Needs to supply continuos signal to the board

 

[Barry_L]

For one you can use a barometric pressure sensor. It will not detect the flow of air but the change in air pressure which is imho suitable for your application.

Or use a fork sensor (like e.g. this one) and add a small flap that is outside the sensor's light path when no air flows, buit is drawn into the sensor's light path by the flow of air, thus interrupting the ligt path and giving a sensor signal.

These are amazing however very cost prohibited. The type of switch I am thinking of is all ready in use for corner store ecigs I am just not sure what they use.

 

[Barry_L]

For one you can use a barometric pressure sensor. It will not detect the flow of air but the change in air pressure which is imho suitable for your application.

Or use a fork sensor (like e.g. this one) and add a small flap that is outside the sensor's light path when no air flows, buit is drawn into the sensor's light path by the flow of air, thus interrupting the ligt path and giving a sensor signal.

https://goo.gl/images/Fsw7QP As shown here