09-07-2011 03:22 AM
Hello
I generated an analog voltage from NI-SCC-68. The voltage is then measured using a voltmeter and produced exactly the voltage that I wanted. For example, if I generated 5V, the voltmeter reads 5V.
However, when I connect the voltage source from the NI-SCC-68 to a thermoelectric cooler (TEC) (at the same time, I measure the voltage output using voltmeter), the output voltage does'nt show the value that I generated. For example if I generated 5V, the voltmeter reads 0V.
Please help me. Is the problem comes from the thermoeletric cooler (TEC)? Because to operate TEC requires current source. So, do I have to change to current source instead of voltage source?
Thank you.
09-07-2011 07:13 AM
TECs are relatively low impedance devices. A 2 cm x 2 cm device might require several amperes of current. They can certainly be operated from a voltage source rather than a current source, but whatever source is used it must be able to supply watts of power. The analog outputs from most DAQ devices can only source a few miiliamperes. You need some kind of amplifier or electronically adjustable power source for your TEC controller.
Lynn