Ideas for circuit requested

[Qvize]

I am looking for ideas for a circuit that will allow a motor to be turned on when the container which houses it is picked up and turns off again when it is put back down.

I know this could easily be achieved by mounting a push-to-break switch on the base of the container but would ideally like to be able to achieve it without any moving parts showing.

Any ideas on achieving this would be greatly appreciated.

 

[David Bridgen]

Anything which must be hidden within the box must surely be a momentary action device such as a mercury or trembler switch.
This implies some latching circuitry and logic to prevent switch-off before the box is put down.
Interesting.

 

[Qvize]

I had thought about using a vibration sensor as a trigger for this but can't see how to use this form of input and still have the motor turn off as soon as it has been put down.

I'm currently wondering whether a couple of flat ended steel probes slightly protruding from the base and linked as an input to a field effect transistor would do the job if the output were to then be run through an inverter. Any ideas if there would be enough resistance in typical surfaces to cause a "trickle" of current to run between the probes and allow this?

 

[David Bridgen]

I think results would be unpredictable.

Does the power have to be removed immediately the box is put down, or could you tolerate some delay?
If you can, then perhaps the movement sensor idea, i.e. mercury or trembler switch, might do it if you incorporate a retriggerable switch-off delay so that once the box is lifted any movement would keep the motor running.

Care to tell me what it's for?

 

[guzzimac]

How about a light sensor in the base of the box?

 

[zachtheterrible]

I don't know the first thing about them, but could a hall effect switch be implimented?

 

[David Bridgen]

How about a light sensor in the base of the box?

Ah, yes. That sounds promising.

 

[k7elp60]

There are all kinds of lever action micro switches that would do that. Mount the switch near the bottom so that when the container is sitting down the level to activated. When the container is picked up the NO contacts will close and start the motor. When the container is set down the N0 contacts will open and turn off the motor.

 

[Phasor]

How about a light sensor in the base of the box?

Schmitt trigger comes to mind. How about this?

Only problems with light sensor - 1) It doesn't work if the box happens to be in the dark, 2) What if somebody accidentally (or deliberately) puts their hand over the sensor?

 

[vne147]

How about an ultrasonic motion detector that would look through a small hole in the bottom of the box. If the box was moved it would see movement but wouldn't be triggered by other movement in the room while it was just sitting on a table or similar surface. Just an idea.