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Wp100

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Hi,

Have a little humidifier, the 12v type thats designed to plug into a car socket.

It works well, but the on /off switch is an inbuilt capacitive sensor.

We are using a micro to turn the power on, but need some method to 'press' the sensor electronically ?

Any suggestions please ...

000309.jpg
 

large_ghostman

Well-Known Member
Most Helpful Member
Hi,

Have a little humidifier, the 12v type thats designed to plug into a car socket.

It works well, but the on /off switch is an inbuilt capacitive sensor.

We are using a micro to turn the power on, but need some method to 'press' the sensor electronically ?

Any suggestions please ...

View attachment 106918
short it out then when the micro switches it on bingo. by short it out i mean at the circuit board connection not the switch end....if that kind of makes sense
 

Wp100

Well-Known Member
short it out then when the micro switches it on bingo. by short it out i mean at the circuit board connection not the switch end....if that kind of makes sense
Thanks, but think you mean the humidifiers circuit board, but I do not want to try and open as it will likely break it, plus the switch needs a single press / pulse, not a press and hold as when tied down/up.
 

Les Jones

Well-Known Member
Most Helpful Member
If it works by capacity loading to ground (Rather than capacity between two or more plates under the sensitive area.) then sticking some foil over it connected by a short thin wire to a normally open contact of a small relay with the other side of the contacts connected to something with a reasonable capacitance to ground may work. A cmos switch such as a cd4066 may work in place of a relay. You would probably need to collect the pin connected to the foil to the ground pin via a high value resistor (10M) so it was not left floating.

Les.
 

Wp100

Well-Known Member
If it works by capacity loading to ground (Rather than capacity between two or more plates under the sensitive area.) then sticking some foil over it connected by a short thin wire to a normally open contact of a small relay with the other side of the contacts connected to something with a reasonable capacitance to ground may work. A cmos switch such as a cd4066 may work in place of a relay. You would probably need to collect the pin connected to the foil to the ground pin via a high value resistor (10M) so it was not left floating.

Les.
Thanks, will give those methods a try.
 

KeepItSimpleStupid

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Most Helpful Member
I don't have anything with a capacitive switch, but I think if you try to activate one with a stick it won't activate. There is no travel with a capacitive switch.
Are you sure it's not membrane?

If it's membrane, the easiest way is an OPTO-FET. This http://uk.farnell.com/excelitas-tech/vtl5c1/optocoupler-single-channel/dp/1652517 isn't made anymore, but it's good for modding. An OPTOMOS relay should work too. It depends on the ON resistance you need.
 

dr pepper

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If your using an arduino you could try something like a 1mH choke in series with a 220 ohm resistor, then use the Tone function in the arduino to apply a frequency to that pin, with any luck you'll be able to create enough magnetic disturbance to activate the sensor placing the choke near it, if this did work your 'duino would be isolated from the device too.
 
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