3-way Valves
The ValveLink8.2 also supports 3-way, single-solenoid valves (2 wires
each). Operate the ValveLink8.2 as you normally would for 2-way valves,
after determining which of two inlets or outlets are opened with the on and
off states. Note that one inlet will always be open with these valves.
Power Supply
The ValveLink8.2 is normally supplied with a 1.5 amp wall transformer.
This is adequate for any valves provided by AutoMate Scientific or a
total of 1 amp of valves opened simultaneously. Please contact AutoMate
Scientific to request a larger power supply if you wish to exceed 1 amp of
valve power (i.e. two 12 watt valves opened at once).
Case and Valve Grounding
This equipment must be earth grounded. Use a #6 screw in any hole
on either side of the ValveLink8.2 case for grounding. Order AutoMate
Scientific part no. 01-05 “Low noise, valve and case grounding package”
for an extra grounding wire attached to each individual valve extending
back to the controller. Each of these items grounds four (4) valves. Please
order two for eight channel perfusion systems. This item must be ordered
at the same time as the valves. Connect the ground wire from the valves to
a screw on the side of the controller case or to your rig's ground point.
chamber where liquid would pass if it overflows. It can also be wrapped
around the outside of a light condenser or inverted microscope objective
turret where liquid would flow if it drips out of the perfusion chamber.
Researchers may create or use their own spill sensors with the
ValveLink8.2. Conductive mats or other commercially-available spill
sensors generally use the same principle as AutoMate Scientific's copper
strips. Likewise, you can easily create your own custom sensor using two
bare wires or conductive pens or epoxy. Inexpensive conductive pens
like those from "Circuit Works
™
" are designed for repairing circuit boards.
They leave lines which quickly dry into silver traces. A similar conductive
epoxy is also available. It makes the connection of two wires to your silver
traces even easier. Simply draw two parallel silver lines approximately
1
/
16
" (1 mm) apart on any surface where leaking liquids would pass. Make
sure the lines do not touch, or draw one wide line and etch a gap down the
middle once it has dried. Then connect a small wire from each trace back
to the spill sensor port on the ValveLink8.2.
Another nice feature of the ValveLink8.2 spill sensor circuit is its dynamic
recalibration. Competing spill sensors simply watch for a low resistance
and trigger. Unfortunately, their conductive mats keep a low resistance
and cannot be reused until they dry. The ValveLink8.2 lets you press
any button to override the spill. Because it is microprocessor-based, the
controller keeps a running value for the sensor resistance and watches for
a 5% drop in resistance. Therefore, even a damp sensor can be used again
immediately as the controller adjusts to the new resistance and watches for
any subsequent leaks by another proportional resistance drop. As the mat
dries, the ValveLink8.2 is constantly monitoring the increasing resistance
and watching for a drop from the latest value.
Where is the power switch? Sleep
The ValveLink8.2 does not have a power switch. As long as it is plugged-
in, it is on. The ValveLink8.2 is perfectly happy being left on forever
and consumes very little power when all valves are closed. However, an
optional sleep mode has been included. Press and hold the "Mode/Sleep"
button until the blue and yellow Mode LEDs begin flashing (about three
seconds) to put the ValveLink8.2 to sleep. In this state all valves and valve
LEDs are off, and all inputs (buttons, TTLs, USB, etc.) are ignored. Press
the Mode button again to wake the controller. Sleep mode can also be used
as an emergency "off" switch if you need to quickly close all valves and
stop the computer inputs.
12V AC Power (up to 2.4 amps @ 50-60Hz)
USB Port and address
(see USB chapter)
Digital inputs
(see earlier section)
Back Panel
12 volt DC valves
1A (12W) max per channel
2A (24W) max total
Spill
sensor
(prev. pages)
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