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This is a
handy little board if you are interested in controlling the
level of a liquid in a vessel. It works based on
conductivity of the liquid so it does not require a moveable
float switch (although they can be used with this design).
It uses Darlington Transistors which enable this circuit to
work with very clean (low conductivity) water. It detects
the presence or absence of liquid at the tip of the probes.
The controlling probes are placed at the desired upper and
lower limit levels. When the liquid level in the
vessel drops below the lower limit probe (opening the
normally closed contact), the 10A relay is activated which
turns on your filling device (pump, solenoid, etc.) and
remains on until the liquid level reaches the upper limit
level probe (a normally open contact) at which time the
relay opens and shuts off your filling device. The
probes for this board can be moveable level switches or
simply stainless steel screws screwed into the
(non-conductive) vessel at the desired levels. They
require 12VDC for operation.
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Version 1 - Control
Only: $23.25 This version will control the
level of water in a reservoir. It is available
in a "Pump Up" (refill when empty) version or a
"Pump Down" (drain when full) version. Please
specify which version you want when ordering.
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Version 2 - Control
and Alarm: $45.25
This version has 4 probes. Two
“controlling probes” and 2 “alarm probes”. The
controlling probes are placed at the upper and lower
limit levels and the alarm probes are placed at
positions outside of the upper and lower level
limits to signal when the level exceeds those
limits. When the liquid level in the vessel drops
below the lower limit probe (opening the normally
closed contact), the 10A relay is activated which
turns on your filling device (pump, solenoid, etc.)
and remains on until the liquid level reaches the
upper limit level probe (a normally open contact) at
which time the relay opens and shuts off your
filling device. If the level exceeds the upper and
lower limits and triggers either alarm probe, the
associated relay will close powering the alarm. The
alarm relays only stay activated as long as the
alarm condition exists. As soon as the alarm
condition ends, the alarm will go off. Only
available in a "Pump Up" (refill when empty)
version.
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