J-KEM Scientific Gemini User Manual - page 16
3.5
Timer Controls
The 100 hour timer works with Channel 1 only, it has no effect on Channel 2.
The timer section turns outlet 9 either ON or OFF in an unattended operation when the time in the counter
expires. To enter a value into the timer press the [UP arrow] or [DOWN arrow] buttons (19) to increase
or decrease the displayed time. The format of the display is ‘Hr : Min’.
A simple way to know whether outlet 9 is on or off is by the state of LED 17 which is lit when the outlet is
on and not lit when it’s off.
Outlet 9 will be ON or OFF depending on the position of switch 18 as outlined in the table below.
Switch 18
Time Remaining
Outlet 9
LED 17
Position
in Timer
is:
is
Comment
[When time = 0
turn outlet:]
Zero
OFF
OFF
OFF
>Zero
ON
ON
Outlet 9 will remain ON until the
timer counts down to zero, at which
point the outlet will turn OFF and
stay off indefinitely.
[When time = 0
turn outlet:]
Zero
ON
ON
ON
> Zero
OFF
OFF
Outlet 9 will remain OFF until the
timer counts down to zero, at which
point the outlet will turn ON and
stay on indefinitely.
3.6
Output Power Level
This circuit (Figure 1, #’s 10 & 11) is the user’s interface to J-KEM’s patented
power control computer which limits the maximum output power delivered by the controller. It
determines whether the controller heats at a very low (1-10 mL), low (10 - 100 mL), intermediate (50 - 500
mL), medium (300 mL - 2 L), or high (>2 L) power level. The power level set for Channels 1 & 2 are
independent of one another.
The output power circuit acts as a solid state variac. This circuit has an additional setting: “Heat Off”
which, when selected, turns heating off and allows the controller to act as a digital thermometer. The
table to the right shows the maximum output power from the controller to the heater depending on the
position of the power switch. The correct setting for this switch is the setting that supplies adequate
power for the heater to heat to the set point in a reasonable period of time while at the same time not
overpowering it.
Heating Liquids. Each power level is associated with a
volume range which acts as a guide when heating solutions
with heating mantles. When solutions are heated with
heating mantles set the power switch to the range that
includes the volume of solution being heated [Note: this
switch is set to the volume of solution, not the size of the
flask]. For example to heat 250 ml of toluene to 80o C in a
1 L round bottomed
Front Panel
Approx. % of
Volume Range
Full Power
1 - 10 mL
3
10 - 100 mL
10
50 - 500 mL
25
300 ml - 2 L
50
2 L
≥
100
flask choose the third power setting (50 - 500 ml) since the solution volume falls within this range. There
are situations when a power level other than that indicated on the front panel should be used:
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