PART
II Cont..
Sensor and Control Electronics
If the diaphragm is misunderstood and maligned, the electronic
sensor component of automatic faucets by comparison is mired
by hate and loathing of many in the plumbing industry. There
seems to be an aura of mystery surrounding these sensors somewhat
reminiscent of that exhibited towards personal computers and
cellular phones when they first came into use. Well I'd like
to do my part in dispelling this mystery first by taking it
away on a long, hopefully entertaining, explanation, and then
by bringing it all home to you. Feel free to email me and
let me know if I did a good job, no hate letters please.
Automatic faucets are presence sensors and not motion sensors.
They employ Active Infrared technology which senses "presence"
and not "movement" of objects. Active infrared technology,
like the name implies is actively emitting infrared light
and actively waiting for this light to come back to it. On
the frequency spectrum, infrared light lies between radio
waves and light waves that are visible to the human eye. To
achieve the task of emitting and receiving, faucet sensors
employ 2 key components: an emitter AKA transmitter and a
collector AKA receiver each about ¼" in diameter and 5/16"long
or smaller. These components are housed within the sensor
capsule that is located either at the neck of the faucet spout,
in a separate sink hole to the side of the faucet spout, or
in a special compartment up next to the aerator. The emitter
is constantly emitting infrared light in a blinking method,
that is, the emitter is constantly blinking in the same way
that turn signals on automobiles blink when the turn signal
lever is engaged. The collector on the other hand, is always
ready to receive (collect) this blinking light, and when it
does, the control electronics take a factory preset action,
in the case of battery powered faucets, the control electronics
send an electrical pulse to the solenoid valve asking it to
open. When the collector no longer receive the blinking light,
the control electronics will then send yet another electrical
pulse to the solenoid, this time, asking the solenoid to close.
Since the emitter emits infrared light in a narrow and focused
beam (imagine the focusing apparatus on a common household
flash light), and since the collector also receives infrared
light in a straight and narrow beam, and since both emitter
and collector point in the same direction never in plane view
of one another, the only way that the collector can receive
the blinking light that is emitted by the emitter is to place
a reflective object in the path of the beam, in most cases
human hands.
I promised you earlier that I will bring it all home to you.
The reason that I want to do so is that some may read the
earlier paragraph and immediately conclude that this automatic
faucet "thing" is advanced technology, too complicated for
plumbing purposes, maybe even extreme, and should never be
used in any consumer level products. This assessment by some
is simply unfair and, more notably, far from the truth. In
fact this technology has been in the palm of your hand, literally,
for well over twenty year. I am talking about TV remote control,
man's new best friend, we all have them, we all love them,
and some of us, can't live without them. Your TV remote control
employs the same active infrared technology that your automatic
faucet does, sometimes the same exact emitter and collector
component. In the case of a remote control the emitter is
located inside the remote control itself and at the end that
points at the TV, whereas the collector is located inside
the TV generally hidden behind an amber color transparent
plastic guard. If you think that faucet sensor and control
electronics are complex .. think again. Whereas faucet sensor
and control electronics act as an On Off switch, a remote
control designed for an entertainment centers, for example,
sends and receives coded messages that are 100,000 to 1,000,000
times more complex than that of the simple on-off function
that faucet electronics perform. Aren't some of us lucky we're
in the plumbing business and not in the TV business?
Batteries and/or Wall A.C.
Automatic faucets draw power from two popular sources: Six
Volt seems to be the standard voltage for battery powered
faucets (for now), although 9 volt is not uncommon. Battery
powered faucets generally employ the services of AA batteries,
C batteries, standard 9 Volt alkaline batteries, or lithium
batteries. These batteries have storage capacities measured
in milliamp/Hour, 1000 milliamp/hour is equivalent to 1 amp/hour
which is enough energy to light up a 1 amp bulb for 1 hour.
Larger size batteries exhibit greater energy capacity than
smaller size batteries, similar to an automobile's gas tank,
the larger the tank the more fuel you can put in it, but only
efficient cars get the longer haul. Which brings us back to
automatic faucets, no discussion of battery powered faucets
is complete without briefly touching on faucet efficiency.
How often you need to replace the batteries depends largely
on how fast or slow the faucet consumes the energy stored
within its batteries. This principally is a none-issue for
AC powered faucets since wall AC is an inexhaustible power
source, until the power goes out of course. AC powered faucets
will be discussed in length later in this chapter. It is worth
mentioning here that the Faucet Automator model FA100sca is
the only faucet automation device- to the best of our knowledge-
with a true AC/DC automatic switchover feature. With the batteries
installed and AC transformer plugged in the device automatically
switches over to AC power from battery power, however, should
the power in the wall go out the device switches back over
to batteries for continuous, uninterrupted service. If anyone
out there is aware of another faucet automation device that
has this feature, please let me know and I will be glad to
revise this writing to include the brand name of that faucet.
AC powered faucets employ transformers and switching adapters
(more on those later) that plug into/or are hard wired to
the wall. Transformers and switching adapters transform wall
AC into 24, 12, 9, or 6 Volt AC or DC depending on the application.
These are generally the 4 voltage ratings that automatic faucets
operate on, at least here in the USA. Transformers and switching
adapters measure their output capacity in VAC, higher VAC
transformers and switching adapters are capable of delivering
steady current at rated voltage to loads that require more
"juice", in this case faucet electronics and solenoids. To
better understand the relationship between VAC and power consumption
by load, one only needs to look at automobile engines. The
larger the engine, the larger the carburetor and fuel line
that feed the engine. The larger the solenoid and electronics,
the larger the VAC rating should be.
I mentioned switching adapters earlier which are commonly
employed for the purpose of supplying power to electronic
equipment. They are generally found along side laptops and
cell phones. There are key reasons why switching adapters
are the power supply of choice for electronic equipment manufacturers,
automatic faucets are no exception. When employing standard
transformers to supply power to modern electronic equipment,
use of these transformers can lead to power quality degradation
and heating problems, here are some of the reasons why:
a. Single phase electronic loads can cause excessive transformer
heating.
b. Electronic loads draw "non-linear" currents, resulting
in momentary low voltage supply and output voltage distortion.
c. Oversizing for impedance and thermal performance can result
in a transformer with a significantly larger footprint, and
weight.
Switching adapters by contrast, are specifically designed
for non-linear loads and incorporate substantial design improvements
that address both thermal and power quality concerns. Such
devices are low impedance, compact, and have better high frequency
performance than standard transformers.
Faucet Spouts
Automatic faucet spoutare not dissimilar to standard faucet
spouts. They're mainly constructed of brass or in some cases,
Zink. It is proper to state a disclaimer here that all MAC
faucets are constructed of brass, MAC faucets does not build
faucets or faucet components out of Zink. Some automatic faucets
are machined, for example: European style faucets, (the MAC
200spl), some are die cast with the water passage made of
copper tubing, and yet some are made of brass that is sand
cast, this type is generally referred to as solid brass for
the large brass content in it. We will discuss the various
forms of castings in Part III.
Automatic faucet spouts are designed for several applications:
standard bathroom fixtures, lab or bar sink faucets, and splash
mount faucets chiefly for food service applications. Beyond
delivering water, spouts mainly encompass an aesthetic purpose.
Style and finish combined are the number one reason why buyers
choose one faucet over the next, therefore much attention
is focused on creating a faucet fixture that is aesthetically
pleasing.
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