Reverse switching a float sensor

[nextural]

Hi,

Standard float sensors are normally used to output to an LED meter so if the water level is above a certain point the LED is on, and when it drops below that point the LED switches off e.g. a small LED meter with red yellow and green level indicators in a motorhome.

Is it possible to reverse the operation of the LED or sensor so that the LED only lights up when the water drops below a certain point? I.e. to use the LED as a 'low water' indicator rather than a level indicator. e.g. Instead of a multi-LED water meter, only a single 'low water' warning LED.

Thanks

 

[Spoon]

You could use a changeover relay to do this.
The float switch would energise the relay and then you could use the Normally Closed contact of the relay to operate the LED.

 

[James]

Many float switches have both normally open and normally closed contacts.

The easiest way to achieve what you are trying to do would be to turn the float switch upside down.

 

[Darkwood]

As above, just buy a cheap relay matching the switching voltage of the device and have it operating the relay, you can then use the N/O or N/C contacts to suit your needs and just ignore the existing light if you cannot disconnect it.

 

[nextural]

thanks all! Shall try inverting it, and failing that relay it is.

 

[James]

The type of float switch you are showing,
When it is one way up, water makes the float rise to horizontal and makes a reed switch, when turned the other way up, when the water has dropped, the float drops back to horizontal and makes the Reed switch.