CWE TC-1000 User manual
TC-1000
Temperature Controller
©CWE 2023
Read instructions carefully before operating this device.
This device is not to be used for Human Life Support applications.
To avoid possible electrical shock, do not operate this device if is wet or has had liquids spilled onto it.
Service or calibration procedures should only be performed by qualified personnel familiar with the
electrical hazards of line-powered devices.
Instruction Manual
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TC-1000 Instruction Manual 2
© 2023 CWE, Inc.
STATEMENT OF WARRANTY
IF THIS INSTRUMENT FAILS WITHIN A PERIOD OF ONE YEAR FROM THE DATE
OF DELIVERY OR INSTALLATION, CWE, INC. WILL, AT ITS OPTION, REPAIR OR
REPLACE IT FREE OF CHARGE. THIS WARRANTY EXCLUDES DAMAGE
INCURRED THROUGH MISUSE OR ACCIDENT. CWE, INC. DOES NOT ASSUME
ANY LIABILITY FOR ANY CONSEQUENTIAL DAMAGES RESULTING FROM THE
USE OF THIS INSTRUMENT.
DEFECTIVE UNITS SHOULD BE RETURNED TO THE FACTORY ALONG WITH A
NOTE DESCRIBING THE NATURE OF THE FAULT. THIS WARRANTY IS
APPLICABLE TO THE ORIGINAL PURCHASER OF THE INSTRUMENT ONLY, AND
IS NOT TRANSFERABLE.
FACTORY SERVICE
Out of warranty or damaged instruments may be returned to the factory freight prepaid
for service at prevailing rates. Upon request, a written or verbal quotation for such
service will be issued after examination of the unit but prior to commencing repairs or
service. Address requests for service or technical information to:
CWE, Incorporated
Technical Support
Ardmore PA 19003
(610)642-7719
LIFE SUPPORT POLICY
Instruments manufactured by CWE, Incorporated are not authorized for use as critical
components in human life support devices or systems. "Life support devices or
systems", as used herein, are devices or systems whose failure to perform, whether
through misuse, failure, or proper operation, can reasonably be expected to result in
significant injury to the operator or subject persons.
This document was last edited on January 25, 2023.
TC-1000 Instruction Manual 3
© 2023 CWE, Inc.
1.0 INTRODUCTION
The TC-1000 Temperature Controller is used to monitor and control body
temperature of small animals over the range of 25 - 45°C. A linear PID
(Proportional-Integral-Derivative) controller smoothly adjusts DC current flow
through the heating pad, without the voltage transients associated with simple
on/off controllers. It accepts thermistor temperature probes in the Yellow Springs
Instruments (YSI) 400 series. A front panel LCD display shows the actual animal
probe temperature, the set-point temperature, the alarm band hysteresis, and
various status messages. The TC-1000 may be used for measuring and
controlling body or bath temperature within the measurement range, using
resistive heaters or heating pads. A range of suitable probes and heating pads is
available, including rectal probes and other fast-response probes.
Front panel view of TC-1000 Temperature Controller
2.0 PROBE CONNECTION
Plug the thermistor probe into the THERMISTOR PROBE input jack. The probe should
be one of the YSI Series 400 family, which are terminated with a ¼” phone plug. A
variety of probes is available. Normally, probes are inserted rectally (but see
Section 8.0 for other possibilities). See Ordering Information at the back of this
manual for descriptions of the available probes.
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© 2023 CWE, Inc.
3.0 TEMPERATURE MONITOR OUTPUT
The TEMPERATURE MONITOR OUTPUT jack provides an analog voltage corresponding
to the displayed temperature measurement. This output can be monitored or
recorded on an external instrument if desired. The scaling of this signal is
100mV/oC. For example, 37.0oC = 3.7V.
4.0 HEATER CONNECTION
The TC-1000 is intended for use with resistive-type heating elements in the range
of approximately 4 - 20 ohms. This corresponds to the mouse-size, rat-size and
cat-size heating pads supplied by CWE, Inc. The maximum available heater power
is approximately 12VDC at 3.5A. The lower the resistance of the heating element,
the higher the heating current that can flow. The heating element is connected to
the 5-pin HEATING PAD jack on the front panel.
CAUTION! Do not use heating elements with a resistance less than
4 ohms using the internal power supply. Lower resistance (i.e.,
higher current) heaters can be accommodated using an external
power supply. See Section 9.0 for details.
5.0 STARTUP AND PAD SELECTION
When power is switched ON, the following dialog will appear on the LCD display:
The display shows the currently configured heating pad; either MOUSE, RAT, or
CAT. If the display does not show the pad you are using, press the TEMP SET knob
repeatedly until the desired type appears. This setting will be stored and
automatically applied the next time the TC-1000 is powered on. This dialog will
time out in 10 seconds if no operator input is received.
The purpose of this configuration is to optimize the heating properties of the
instrument for the size of pad being used.
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© 2023 CWE, Inc.
6.0 SETTING THE TARGET TEMPERATURE AND ALARM BAND
The image shown below is the main operating and control display. The monitored
temperature is shown on the first line of the LCD display panel. The second line
shows the target (set-point) temperature and alarm hysteresis band:
The SET temperature is the desired body temperature that is to be maintained.
Rotate the SET TEMP knob until the desired set-point is displayed.
The second number shown on line 2 is the alarm band hysteresis. This is the
deviation from the set-point that is allowable before the alarm will be activated. In
the example above, the alarm band is set to 36.5o - 37.5o. The alarm band is
always symmetrical around the set-point temperature. If the measured
temperature goes outside these bounds, the temperature alarm will be activated.
To adjust the alarm band hysteresis, push in the SET TEMP knob while turning it,
until the desired alarm band is displayed on the LCD. Both set-point temperature
and alarm settings are saved in non-volatile memory, and will be restored when
the unit is next used.
The third line shows the alarm status, In this case, the audible temperature alarm
is turned OFF.
The fourth line shows a bar graph of the relative heater being applied. In the
bottom right corner is an indicator showing which pad configuration is being used:
M = mouse, R = rat, and C = cat.
7.0 ALARMS AND FAULT CONDITION ALERTS
The TC-1000 is equipped with a user-adjustable temperature alarm, and additional
fault condition monitors. The various conditions and operator messages are
described below.
Temperature Alarm –This is a user-adjustable temperature band that is set up as
described in Section 6.0. When triggered by an out-of-temperature condition, the
ALARM pushbutton switch will be illuminated, and the third line of the LCD display
will show the message Temp Alarm!
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© 2023 CWE, Inc.
If the audible alarm is active, a short beep will sound every four seconds. To turn
off this beep, press the ALARM pushbutton switch. The visible alarm light and LCD
warning message will be displayed regardless of the audible alarm setting.
Probe Error - The message Check Temp Probe indicates that there is a problem
with the thermistor probe: it is either unplugged from the TC-1000, broken, or out
of the normal operating range. Be sure the probe is connected properly, or replace
the probe if necessary. A short beep will sound every 1.5 seconds to alert the user
that this condition must be corrected. While this message is displayed, heating
power is turned off to avoid overheating of the animal.
Probe-Animal Error - The message Check Animal/Probe is displayed if the TC-
1000 has been heating the animal for some time (10 minutes), but the animal
temperature remains at least 6oC below the desired set point. The most common
cause of this condition is that the probe has become disconnected from the
animal. A short beep will sound every five seconds to alert the operator to correct
this condition. When this message is displayed, heating power is turned off to
avoid overheating of the animal.
NOTE: After the probe/animal connection is re-established, press the
ADJUST knob momentarily to reset the alarm condition and re-start the
heater. Normally, the animal’s body temperature will be sufficient to
reset the alarm condition.
8.0 HOMEOTHERMIC WARMING STRATEGIES
While the operation of the TC-1000 Temperature Controller system is
straightforward, some simple considerations will help in achieving good results.
Keep in mind that the controller actually works by attempting to keep the
thermistor probe at the set temperature.
Strategy 1: Simple, continuous warming --- This is the most common
application. It is desired to keep the experimental animal warm during a surgical
procedure or other experimental session lasting an indefinite time.
Procedure: Place the animal on the heating pad and insert the probe rectally. Be
sure there is some minimal insulation underneath the pad to prevent excessive
heat loss to surgical table, stereotaxic apparatus, etc. If possible, try to cover the
animal with a small drape (or even a paper towel). This reduces heat radiation to
the environment, especially in a cold room.
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© 2023 CWE, Inc.
Strategy 2: Intermittent use with one or more animals --- In this situation, the
animal is warmed for a while, then removed from the pad (perhaps for a separate
test or measurement, etc.), then returned to the pad. A similar situation would be
to sequentially warm a series of animals (e.g., during surgery, with the pad being
unoccupied between animals).
Procedure: Place the animal on the heating pad as usual and insert the probe
rectally. When the pad is not in use (i.e., the time between animals), place the
temperature probe on the surface of the heating pad. This simple procedure
prevents the controller from ramping up its heat output when no animal is present,
and prevents overheating the next animal in the sequence.
Strategy 3: Fail-safe simple warming technique --- If the object is to simply
keep the animal warm, and it is not too critical to maintain an exact body
temperature, then use this procedure.
Procedure: Place the animal on the heating pad as usual, but place the
temperature probe underneath the animal, i.e. between the animal and the heating
pad. The controller will then keep the surface temperature of the pad at the set
temperature. This prevents any possibility of overheating or heat injury to the
animal. Researchers who use this technique typically set the target temperature a
few degrees above the normal body temperature (say, to 40o C) to allow for heat
loss to the environment.
Note: This procedure can also be used to keep a number of small animals (e.g.,
newborn rodents) warm at the same time. Use this technique to create a small
incubator by placing the pad on the floor of a small plastic enclosure.
Strategy 4: General hints and suggestions --- Please observe the following
suggestions and precautions to enable successful operation of this instrument.
Do not: Place the heating pad directly on a cold table, metal plate, or other heat
conducting surface. You will be asking the heating pad to warm a far larger mass
than it is capable of, and it will not work!
Do: Place a small insulating layer between the heating pad and the underlying
surface. This will serve to isolate the pad/animal thermal system.
Do: If possible, place a small covering over the animal. This limits heat loss to the
environment, especially if the area is cold or drafty.
Do: Allow sufficient time for the system to stabilize. It will take a minimum of
several minutes for the controller to adapt to the prevailing conditions. The
controller is designed not to overshoot the set temperature. Consider the task: the
heating pad is radiating and/or conducting heat to the body of the animal, and thus
eventually to the thermistor probe. There is a considerable time lag in response,
and the controller tries to anticipate the future temperature of the probe/animal,
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© 2023 CWE, Inc.
without applying so much heat that the desired endpoint will be exceeded. Not
such an easy task!
9.0 CONNECTING AN EXTERNAL POWER SUPPLY
The TC-1000 is designed for direct use with heating blankets or immersion heaters
in the range of 4 –20 ohms. Lower resistance heaters can be used, but require a
higher current power source than is built into the TC-1000.
To use a higher power blanket or other heater (up to 10A, or resistance down to
about 1 ohm), an external power supply should be connected to the rear panel
binding posts, using the following procedure:
WARNING! Be sure power is turned OFF before connecting or
disconnecting an external power supply!
1. Locate the three binding posts on the rear panel of the TC-1000.
2. Remove the jumper that connects the INTERNAL (red) and EXTERNAL (yellow)
binding posts.
3. Connect a suitable power supply to the EXTERNAL (yellow) and GROUND (white)
binding posts, observing correct polarity (positive to yellow, negative to white).
CAUTION: The external power supply or battery should be capable
of supplying 12VDC, with a current rating consistent with the
heating pad being used. Be sure to remove the jumper between
the INTERNAL and EXTERNAL binding posts when using an external
power supply. Do not connect any external power source to the
INTERNAL (red) binding post!
4. Replace the HTR POWER FUSE with a 10A fuse. Be sure to replace this fuse with
the original 4A fuse when again using the internal power supply.
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© 2023 CWE, Inc.
10.0 SETTING MAXIMUM PAD HEAT OUTPUT
The controller firmware stores a maximum power output level for each type of
heating pad. This value is automatically used when the user sets the “Pad in use”
as described in Section 5.0. The purpose of this is to limit the maximum power
available during heating, and thus limit the pad surface temperature. It is possible
for the user to change this limit using the following procedure:
CAUTION: The factory-set values are carefully determined to
prevent excessive heating pad surface temperatures. Do not
change these values unless there is a real need to do so. A valid
reason would be an unusual heating situation requiring more heat
than usual. When using our standard heating pads, you should not
need to alter the default values.
To activate this procedure, press the ALARM pushbutton briefly while powering the
instrument ON. After the usual “Pad in use” screen has appeared and timed out,
the following display will appear:
To display shows which pad will be affected (MOUSE, RAT, or CAT), and the
current power level limit. To change the limit, rotate the SET TEMP knob. When the
desired reading appears, press the SET TEMP knob to store the value and exit. This
value will be stored internally, and active whenever this pad is being used.
The maximum setting is 4095, which will allow full power to be applied by the
controller. Effective settings are within the range 3000 –4095, with higher values
permitting more heat to be delivered to the pad.
Note: If you just want the maximum power, select [CAT] in the “Pad in use” dialog
at startup. Because of its large surface area, the cat pad is already configured with
the maximum power setting.
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© 2023 CWE, Inc.
11.0 ORDERING INFORMATION
Part No.
Model
Description
08-13000
TC-1000 Mouse
Temperature controller with mouse probe and heating pad
08-13001
TC-1000 Rat
Temperature controller with rat probe and heating pad
08-13099
TC-1000
Temperature controller, main unit only
08-13013
Heating Pad, Mouse
Flexible flat pad, 3 x 6” (7.6 x 15.2cm)
08-13014
Heating Pad, Rat
Flexible flat pad, 5 x 7” (12.7 x 17.8cm)
10-09012
YSI-451
Mouse thermistor probe, 1mm dia.
10-09010
YSI-401
Thermistor probe, cat-size, 4.75mm dia.
10-09020
YSI-402
Thermistor probe, rat-size, 3mm dia.
08-09214
THPROBE-EXT
Thermistor probe extension cable, 12’ (3.6m)
08-09215
THPAD-EXT
Heating pad extension cable, 12’ (3.6m)
