Electronic gurus - regarding tilt sensors?

[Chalkie]

I'm currently working on a uni assignment and am designing a Blender type product. The design is a hand held unit and requires the motor to turn on ONLY once the product it is inverted. Here's a simple example with a water bottle to demonstrate. The motor would be in the highlighted regions.

Anyway, I know you can get tilt sensors that engage contact at a certain angle but its normal less than 80°. But, I havent been able to find any that engage at around 180°, does something like this exist?

 

[rayza]

it needs to be fairly compact,yes? most cheap tilt switches are mercury type, so you wont get the 180degree's out of them. usually, for that sort of range, you'd be looking at using an incliometer, but this requires having an sensor and controller to most like end up with an analouge signal which you then convert to suit your application, none of this i believe will suit your application. in my opinion, the cheapest way to get what you wanted would be to use a regular micro switch with a weight setup to operate at 180degree's. though remeber, the switch must be rated to handle the current draw of the motor.

 

[Jon]

nhp.com.au

All sorts of switch type shit on there. We use them for work applications.

 

[Binaural]

A simple tilt switch might not be reliable enough for you. One other option other than sensing the orientation of the bottle is detecting whether fluids/solids are pooled in the very top of the neck (i.e. upside down). I see a couple of ways you could detect that:

1) a cheap and nasty solution for a concept prototype is to use some sort of resistance measurement. You could use a simple circuit to switch on when resistance between two probes is low (i.e. liquid connection). Dead simple, can be done in a few minutes for a demonstration system.

2) a capacitive proximity sensor (similar to a touch sensor) to detect filling of the head. These are pretty simple, and you can buy chips that do the hard work of interpreting a capacitance signal for you.

In any case (including with microswitches), you need to get a second or two of on-delay timing to prevent the motor going off whenever the bottle is shaken. A 555 timer and resistor could do this and there's lots of "cookbook" style building instructions on the web.

 

[Chalkie]

Cheers for the posts guys. I don't need to build a prototype, but I do need to specify parts from suppliers that would be used if the thing went into production (its a 'design for manufacture' project).

Jon
No luck with the link there. Got another one I can try?

Rayza
Yeah, compact is the key here. The smaller the better. after doing some further reading tilt sensors defiantly aren't what I'm looking for. Will try look for some more info on micro switch circuits and see what I can come up with.


Binaural.
A capacitive proximity sensor sounds like a good option but from looking around, will be very expensive. I'm aiming for under $10ish for the mechanism (switch, resistor, timer, etc...) (quantities of 2,000+ though) Already been looking into timers. I reckon a 555 timer will work for this as you said.

Do you have any links or more information to the other suggestions you have... I'm know only the very basics when it comes to electronics?

Edit: I don't need to have a full working circuit diagram for this (although it'd be a nice extra) but I do need to have all the right components that will work together.

 

[Chalkie]

So, this was the solution (as suggested by a member over at OCAU).

So simple and it works perfectly.