Is this a switch?

[boscoe99]

When the two exposed terminals of the device depicted below are surrounded by water the water bridges the two terminals and through the magic of electronics a light illuminates or a horn sounds. Water is now doing what a piece of metal might be doing, although with a piece of metal the electronics need not be involved.

Who considers this to be a switch and who does not? Why?

Just trying to better understand difffering opinions and the basis for us having them. I even argue with myself from time to time.

[99yam40]

I would call it a sensor probe as it does not do anything but send a signal to some other electronic device to do something with that signal/
a switch will connect or disconnect a circuit

[fairdeal]

that is a good one.
imagine it is labeled for sale as a "water sensor"....

I suppose the answer depends on the details of that attached "electronic magic"


on my F225, there are temperature switches, and a temp sensor.

The switches tell the ECU that their state has changed - so the ECU alarms.

Whereas the temp sensor "reports" a varying range of values -

from which the ECU "decides" to switch on an alarm -



nah - its just semantics.....

[boscoe99]

I would call it a sensor probe as it does not do anything but send a signal to some other electronic device to do something with that signal/
a switch will connect or disconnect a circuit

If, instead of water bridging the terminals to complete a circuit, a float was used to raise a piece of metal to bridge the terminals and complete a circuit would that now be a switch or would it be a sensor?

[fairdeal]

haha yes I was thinking of the float type.

So yes, that would clearly be a "switch"

(or could we say that the float "senses the water" ?)

[Sequoiha]

It is a switch, either on or off, it completes a circuit .

[zenoahphobic]

A switch would in the past be regarded as having open circuit and then "switch" to very low resistance.
As the thing in question has relatively high resistance it would have been relatively useless as a switch. That is prior to electronics, that enabled "trans resistance" to enable any amount of resistance to be amplified to drive higher current uses.
I think it technically provides information to electronic gizmos to switch some thing that we can detect without further modification.
We have accepted that these things are all sensors or probes at one end and perhaps in this case it's output is interpreted as a switch, stablising the output resistance, as water resistance between salt, brackish and fresh varies greatly.

[rodbolt17]

pure water as in reagent water has almost no conductivity.
most water conducts.
it is a switch just like a mercury switch.
the resistance of water is measured in micro mos.
but once enough water is present the circuit closes it is an on or off switch.

[cpostis]

beat a dead horse by Charles Postis, on Flickr

Well, it contains a switch. However, it is also a sensor. The two sensor probes measure continuity the circuitry reacts to the sensors input. Once the continuity rises above a certain level (when water is between the two probes) it closes another circuit (the switch). It does not send a variable measured field signal.
Same as the typical Yamaha thermo-switch. It contains a switch, a bi-metal that reacts and expands with temperature (the sensor) and makes contact above a certain temperature (the switch) closing the circuit. It does not send a variable measured field signal.
So, maybe they both should be called a "sensor switch"?
Now, a typical Yamaha engine temperature sensor is not a switch. It reacts to temperature change and decreases resistance as temperature increases, a negative temperature coefficient thermistor. A “valve” if you will. It does send a variable measured field. So, “sensor” is correct name for this?
What about a cooling circuit thermostat? Not electrical in any way, shape, or form but It does sense temperature and reacts by opening the “valve” (if you will). As temperature increases, the valve opens more to increase flow through the cooling circuit. It is variable. Should it be called a “thermostat sensor valve”?

Bottom line, Yamaha and other manufacturers calls its components what they do, others may want to call them something else. If you know what they do, how they work, and the effect they perform; you’ll be ok. In the forum, call them what Yamaha does as not to confuse any/all!

[fairdeal]

Here is Boscoe's "device" - clearly and unequivocally a "switch"




Here is the exact same device - but now its a "sensor'

[99yam40]

But the 1st pic shows it turning on a light which the device cannot do without something else to carry the load that the light requires to light up

[cpostis]

Terms are terms, how each interpret them can and will be different.

Why not call the component in the first diagram a "sensor switch" (it senses and makes breaks a switch, technically the closing of the switch sends a signal that a parameter has been reached) and the component in the second diagram a "sensor transmitter" (it senses and transmits a variable signal)?

Man, that horsemeat is sure gonna be tender!

[fairdeal]

But the 1st pic shows it turning on a light which the device cannot do without something else to carry the load that the light requires to light up

Not true. Although it is probably not used that way.

Here is a similar device that was used by the Continental Water Co. to monitor deionization canister output;

nothing more than two bare probes which threaded into the outlet pipe,
a neon bulb, and some lamp cord - plugged directly into a 120V wall outlet.

When the canister became exhausted (IIRC, water resistivity dropped to <1 megohm)
the neon bulb lit. Time to change out the canister.

[99yam40]

did not think about a neon, LED, or other types of lights that do not take much voltage or current to make them work.
I guess I would call something like that , that could do the job on its own a switch.

But other situations where it would send a varying amount of voltage,current, or resistance to something else to so it could turn something on and off I would not.

most everything I had seem had the alarm system isolated from the product with electronics, so the Battery System (power)would not get compromised going to ground or stray voltages from the processes

[boscoe99]

If a switch being closed is on and a switch being open is off, what about a door?

Why isn't a door on when it is closed and off when it is open?

Isn't the English language silly as hell?

Reminds me of Gallagher. He was just learning about words. He first learned the word big. Then he learned the word little. Then he learned what they meant. He was confused. The word little was twice as big as the word big. He knew then that going to school was going to be hard. Or difficult.