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wireless reflective switch

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Scooter

New Member
I want to monitor two air activated switches but they can't be powered. Has anyone heard of a polarized reflector that could be closed when not active and open when active, thus utilizing a transceiver type circuit to signal my controller?. If this isn't feasible, the next idea is to use some low power ir of rf signal. The battery would have to be extremely long lasting. Any ideas??

Thanks,
Scott
 

john1

Active Member
Hi Scott,

I have seen a type of electric air heater with an 'air activated'
switch, its job was to prevent the element from being energised
if the fan wasn't running.

It was a sort of flap that worked a micro-switch.
I suppose the element would burn out if the fan didn't run.

The only switch that i can think of which is not powered,
and can be operated by radio transmissions,
is a 'coherer', a very early detector.
Their disadvantage is that they close ok, but need help to open.

Perhaps you could explain a little clearer what you actually
want, as i cant quite make it out.

Regards, John :)
 

Scooter

New Member
a little more info

Hey John,
Thanks for the interest in my project. I have two dynamic air bladders attached to two air switches. If the bladders are compressed, it sends a puff of air into the switch, which then switches states. In my case they are open until activated. The switch has two terminals on it which are used as dry contacts to signal a plc to monitor whether or not the bladders have been compressed. I've been using a "telephone" type coil cord to hard wire the switches but would prefer to go wireless, thus eliminating the need to repair the cord continuously. I can build filters and such to isolate the signal from interference. I just want to be able to "see" the switch change state without having to externally apply power to it. Maybe an infrared signal that will excite or charge a small battery to transmit a signal back to the receiver??? What do you think?
 

john1

Active Member
Interesting.

A puff of air?
A puff of air to send a signal without wires ?

well,
that suggests a pipe-whistle to me.

Two of them, maybe two different pipe-whistles.
A suitable circuit could pick out a tone easily,
even from a lot of background noise.

If i wanted to do that,
i would probably get one of those 'whistle key rings'
then i would fiddle with the pipe whistle until it
made the key ring respond, and take it from there.

How come its a puff of air, not continuous ?
 

john1

Active Member
I have re-read your posts carefully,
and i think that your switches are to indicate
that the bladders are inflated,
and that they move about in some way, causing the
cord to fail regularly.

I take it you want to tell that the bladders are
inflated without any trailing wires which could fail.

Have you considered having a length of tubing like
that on a fishtank pump over to a stationary switch
from the bladder(s),
the stationary switch could be operated by a diaphragm.
Such small bore plastic tubing is very sturdy and
flexible, i would think it could flex for a very long
time before sustaining any damage.

Still thinking about this.
Could you give me some more details of the set-up or
arrangement you are using please.
Does it involve water and things that float ?

Regards, John :)
 
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