Wavelength Electronics WTC3243 User manual

© 2005
WTC3293-14000 BOARD WITH DISPLAY
WTC3293-14400-A Rev E www.teamwavelength.com
GENERAL DESCRIPTION:
Simply stable temperature control. Wire your
thermoelectric cooler and thermistor to the
board with the cable provided. Add the
appropriate DC power supply and indicate the
expected voltage on the jumper. With the
output disabled, adjust the on-board 12-turn
trimpot and watch the setpoint temperature
change on the 4-digit display. Switch to Actual
and display your thermistor temperature.
Watch the LED tree to see “over / under
temperature” or “stable at setpoint” status.
Enable the output current and watch the
temperature quickly lock in on the setpoint.
Figure 1
Top View
WTC3243 Thermoelectric Temperature
Controller Board with Display
WTC3293-14000 Series
FEATURES:
• Low noise, maximum temperature stability
commercially available
• Display thermistor temperature directly - no
tables to convert resistance to temperature
• LED indicator shows over temperature,
stable at setpoint, or under temperature
status
• Adjust setpoint with a 12-turn potentiometer
or an external voltage
• Control temperature using a 10kΩ
thermistor
• Fixed resistors set Proportional Gain,
Integrator Time Constant, and
thermoelectric current limits
• Enable/Disable Output Current Switch
• Includes Output Cable & DC Power Supply
• Works with a wide range of thermoelectrics
WTC3243 INCLUDED
August, 2005
Online Design Tools at
www.teamwavelength.com

www.teamwavelength.com© 2005
WTC3293-14000 BOARD WITH DISPLAY
PAGE 2
WTC3293-14400-A Rev E
The display is calibrated for a specific 10 kohm thermistor, the TCS610:
where T is in Kelvin; R is in ohms,
A = 1.1279E-3; B=2.3429E-4; C=8.7298E-8
Bias Current is also chosen for this thermistor: 100µA
Fuse: For safety, a 3A fuse is included on the board. Replacement part number is Littelfuse 297 003
(ATO MINI 3A).
Power supply input jack accepts a 2.5mm diameter plug.
ORDERING INFORMATION:
The boards are configured for the power supply you intend to use.
+7V or +9V +12V
Order WEI part number: WTC3293-14001 WTC3293-14002
[WTC3243 & thermal
solution kit included]
Power Supply: 7V DC supply: PWRPAK-7V 12VDC supply: PWRPAK-12V
Order WEI part numbers: 9V DC supply: PWRPAK-9V
Note: Control temperature range for the 10kΩsensor is 10°C to 50°C.
Quick Reference: CONFIGURATION
1/T = A + B(ln R) + C(ln R)3

www.teamwavelength.com© 2005
WTC3293-14000 BOARD WITH DISPLAY
PAGE 3
WTC3293-14400-A Rev E
STEP 1: SELECT POWER SUPPLY VOLTAGE and INSTALL JUMPER
This board has been designed to work with various thermoelectrics. The power supply voltage must
be tailored to the resistance of the thermoelectric to keep the WTC3243 intact. You need a power
supply voltage high enough to drive the thermoelectric, but not too high to overdrive the WTC3243.
1. Determine your maximum thermoelectric voltage and current: Vmax, Imax.
2. The WTC3243 drops about 1.7V, so the minimum power supply voltage is Vmax + 1.7V.
3. Choose from available power supplies. For example, if your thermoelectric will need 5V, the
minimum supply voltage is 6.7V. WEI offers a 7V power supply.
4. Calculate the actual power dissipated in the WTC3243: Power = Imax x [Vsupply - Vmax]. For example,
if you need 1.5Amps and plan to use a 7V supply, Power = 1.5 x [7-5] or 3 Watts. The maximum
power dissipation of the WTC3243 is 9 Watts (with fan & heatsink).
Install a jumper indicating which power supply you have selected on the header near the DC input
plug. NOTE: When you plug in the supply, make sure the Enable Switch is OFF. Do not operate
with a voltage less than 7V.
WHY? The WTC3243 is designed to drive currents as high as 2.0 Amps. The resistance of
the thermoelectric will create a voltage drop across the thermoelectric proportional to the current
(Voltage = Current x Resistance). The voltage drop across the WTC3243 will equal the power
supply voltage minus the thermoelectric voltage. If the power dissipated by the WTC3243 is too high
(Power = Voltage x Current), the WTC3243 will overheat and be destroyed.
STEP 2: SELECT HEAT AND COOL CURRENT LIMITS
To protect the thermoelectric from over current damage, set the heat and cool current limits as follows.
The standard product is shipped with 2.00kΩresistors for 0.5A cooling and heating limits.
Resistors should be 5% metal film. Carbon resistors will introduce noise and instabilities.
OPERATING THE WTC3293-14000
Maximum
Output
Currents
(Amps)
Current
Limit Set
Resistor,
(kΩ)R
A
,R
B
Maximum
Output
Current
(Amps)
Current
Limit Set
Resistor,
(kΩ) R
A
,R
B
Table 1
Current Limit Set Resistor vs
Maximum Output Current
0.0 1.60 1.2 3.05
0.1 1.69 1.3 3.23
0.2 1.78 1.4 3.43
0.3 1.87 1.5 3.65
0.4 1.97 1.6 3.88
0.5 2.08 1.7 4.13
0.6 2.19 1.8 4.42
0.7 2.31 1.9 4.72
0.8 2.44 2.0 5.07
0.9 2.58 2.1 5.45
1.0 2.72 2.2 5.88
1.1 2.88 2.3 6.36
Online, SOA calculators are at http://www.teamwavelength.com/tools/calculator/soa/defaulttc.htm.
You can vary heatsink temperature, power supply voltage, etc. to design a system that will not
dissipate too much power in the WTC3243.

www.teamwavelength.com© 2005
WTC3293-14000 BOARD WITH DISPLAY
PAGE 4
WTC3293-14400-A Rev E
STEP 3: SELECT PROPORTIONAL GAIN AND INTEGRAL TIME CONSTANT
To optimize the control loop (minimize overshoot, settling time, avoid cycling, etc.) change the control
parameters as shown below. If the load doesn’t stabilize, contact the factory for troubleshooting
advice. Resistors should be 5% metal film. Carbon resistors will introduce noise and instabilities.
Note: If you want to use values not listed, use the web based WTC3243 design calculator to
determine resistance values.
STEP 4: WIRE OUTPUT CONNECTOR
Connect the Thermoelectric wires to the Red and Black cable wires as shown. If the polarity is
reversed, the system will only heat. Connect the thermistor wires to the Green and White cable
wires (polarity is not important).
OPERATING THE WTC3293-14000
Table 3 Proportional Gain and Integral Time Constant settings
P value; Resistance
P = 10 A / V
R = 10kΩ
P = 10 A / V
R = 10kΩ
P = 20 A / V
R = 24.9kΩ
Load Size
Small (~0.25 oz)*
Medium
Large
*Default
I value; Resistance
3 seconds
R = 31.6kΩ
3.75 seconds
R = 24.9kΩ
4.5 seconds
R = 20kΩ
Table 4 - OUTPUT CABLE wiring for Thermoelectric
Wire Color FunctionPIN #
RED
GREEN
WHITE
BLACK
1
2
3
4
OUTPUT B - Positive TE wire
SENSOR +
SENSOR -
OUTPUT A - Negative TE wire
Table 5 - OUTPUT CABLE wiring for Resistive Heater
Wire Color FunctionPIN #
RED
GREEN
WHITE
BLACK
1
2
3
4
OUTPUT B - One side of RH
SENSOR +
SENSOR -
OUTPUT A - NO CONNECT
Connect other side of RH to V+
Change RLIM A to 1.5kΩto limit the
cooling curent to ZERO.
Resistive Heater operation assumes
NTC sensor.
Note: If you want a wiring diagram with values, use the online WTC3243 design calculator.

www.teamwavelength.com© 2005
WTC3293-14000 BOARD WITH DISPLAY
PAGE 5
WTC3293-14400-A Rev E
OPERATING THE WTC3293-14000
STEP 6: ADJUST THE SETPOINT TEMPERATURE
The setpoint temperature can be adjusted from 10 to 65°C either by using the onboard 12-turn
potentiometer.
The VSET wire pads can be used as test points to monitor the potentiometer setting or for
connecting an external voltage source (such as a function generator). If an external voltage source
is used, set the setpoint potentiometer approximately mid-range (1 to 1.5V). The input voltage
range is 0 to 2.5V which corresponds to 0 to 25kΩof thermistor resistance. [Transfer function is
10kΩ / V.]
STEP 7: ENABLE THE OUTPUT CURRENT & MONITOR IN-RANGE STATUS
The switch next to the In-Range indicator enables and disables current through the thermoelectric.
The green LED on the In-Range indicator lights when the actual temperature is within 0.05°C of the
setpoint. If the actual temperature exceeds the setpoint, the upper LED will light. If it is below the
setpoint temperature, the lower LED will light.
STEP 5: VIEW THE SETPOINT and ACTUAL TEMPERATURE
The switch next to the setpoint potentiometer determines whether Setpoint or Actual temperature
is displayed. When the setpoint is displayed, the rightmost decimal point is lit. The resistance to
temperature conversion software assumes the thermistor bias current is 100µA and the thermistor is
characterized by the Steinhart-Hart relationship:
where T is in Kelvin; R is in ohms, A = 1.1279E-3; B=2.3429E-4; C=8.7298E-8 (TCS-610)
If another thermistor or bias current is used, the temperature display will not be properly calibrated.
To use another sensor or change the calibration, contact the factory.
1/T = A + B(ln R) + C(ln R)3
Setpoint Potentiometer
Setpoint/Actual
Display Select Switch
In-Range Indicator
Enable/Disable
Switch

www.teamwavelength.com© 2005
WTC3293-14000 BOARD WITH DISPLAY
PAGE 6
WTC3293-14400-A Rev E
MECHANICAL SPECIFICATIONS
2.25”
2.25”
Max height from top side of PCB to fan is 1.5”
Standoffs are 0.625” tall
Board thickness is 0.60”
Allow 0.375” clearance from bottom side of PCB for airflow.
2.00”
0.125”
1.00”0.625”
0.08”
0.36”
0.115”
0.125” dia thru 4x

www.teamwavelength.com© 2005
WTC3293-14000 BOARD WITH DISPLAY
PAGE 7
WTC3293-14400-A Rev E
NOTICE:
The information contained in this document is
subject to change without notice. Wavelength
will not be liable for errors contained herein
or for incidental or consequential damages in
connection with the furnishing, performance, or
use of this material. No part of this document
may be photocopied, reproduced, or translated
to another language without the prior written
consent of Wavelength.
SAFETY:
There are no user serviceability parts inside
this product. Return the product to Wavelength
Electronics for service and repair to assure that
safety features are maintained.
LIFE SUPPORT POLICY:
As a general policy, Wavelength Electronics, Inc.
does not recommend the use of any of its products
in life support applications where the failure or
malfunction of the Wavelength Electronics, Inc.
product can be reasonably expected to cause
failure of the life support device or to significantly
affect its safety or effectiveness. Wavelength
Electronics, Inc. will not knowingly sell its products
for use in such applications unless it receives
written assurances satisfactory to Wavelength
Electronics, Inc. that the risks of injury or damage
have been minimized, the customer assumes
all such risks, and there is no product liability
for Wavelength Electronics, Inc. Examples or
devices considered to be life support devices are
neonatal oxygen analyzers, nerve stimulators (for
any use), auto transfusion devices, blood pumps,
defibrillators, arrhythmia detectors and alarms,
pacemakers, hemodialysis systems, peritoneal
dialysis systems, ventilators of all types, and
infusion pumps as well as other devices designated
as “critical” by the FDA. The above are
representative examples only and are not intended
to be conclusive or exclusive of any other life
support device.
CERTIFICATION AND WARRANTY
CERTIFICATION:
Wavelength Electronics (WEI) certifies that this
product met it’s published specifications at the
time of shipment. Wavelength further certifies
that its calibration measurements are traceable to
the United States National Institute of Standard
and Technology, to the extent allowed by that
organization’s calibration facilities, and to the
calibration facilities of other International Standards
Organization members.
WARRANTY:
This Wavelength product is warranted against
defects in materials and workmanship for a period
of 90 days from date of shipment. During the
warranty period, Wavelength, will, at it’s option,
either repair or replace products which prove to be
defective.
WARRANTY SERVICE:
For warranty service or repair, this product must
be returned to the factory. For products returned
to Wavelength for warranty service, the Buyer
shall prepay shipping charges to Wavelength and
Wavelength shall pay shipping charges to return the
product to the Buyer. However, the Buyer shall pay
all shipping charges, duties, and taxes for products
returned to Wavelength from another country.
LIMITATIONS OF WARRANTY:
The warranty shall not apply to defects resulting
from improper use or misuse of the instrument
outside published specifications.
No other warranty is expressed or implied.
Wavelength specifically disclaims the implied
warranties of merchantiability and fitness for a
particular purpose.
EXCLUSIVE REMEDIES:
The remedies provided herein are the Buyer’s sole
and exclusive remedies. Wavelength shall not be
liable for any direct, indirect, special, incidental,
or consequential damages, whether based on
contract, tort, or any other legal theory.
WAVELENGTH ELECTRONICS, INC.
51 Evergreen Drive
Bozeman, Montana, 59715
phone :[phone] Sales and Technical Support
[phone] Accounting
fax: [phone]
e-mail: [email protected]
web: www.teamwavelength.com