In need of help....choosing electronic components!

[user1234]

Hi guys
Complete novice here.......

Scenario: to build a circuit that cuts out electricity to a motor that is inflating and air bed.
So basically, when a certain pressure is reached, the motor will cut out to ensure over inflation doesn't occur!

My thoughts are a digital air pressure gauge but i have no clue which chip to use to help compute this

Any help is greatly appreciated

Thanks

 

[Diver300]

Something like this:-

SENSORTECHNICS|RBIP015DB|PRESSURE SENSOR, AMPLIFIED | Farnell United Kingdom

That will measure the pressure. Then you need an op-amp to decide when the pressure has got to the right level, a transistor to amplify the output of the op-amp, and a relay to turn the motor off.

Or buy one of these. **broken link removed**

Certainly cheaper than a on-off electronic solution.

They tend to use centrifugal pumps that are very quick at shifting a lot of air, but can't produce too much pressure. Filling an air bed from a high pressure pump takes ages but you can easily over inflate it.

 

[Hero999]

How are you going to stop the air bed from deflating when the motor turns off?

Is the motor connected to a fan or a reciprocating pump? Does it have a non-return valve?

Awhile ago I made an air bed inflating machine from an old vacuum cleaner motor which the bed inflated in under a minute. The fan was also powerful enough to inflate balloons which was difficult because it inflated them so quickly that the balloon normally burst before you had time to turn the motor off.

What about something simple, such as a balloon that pushes against a normally closed micro switch when it inflates past a certain point, thus opening the switch and cutting oof the motor?