Students Muhammad Sheroz Malik
Time Frame Summer 2015
Supplementary Materials Student Report Peltier Heater Control VI File

A bi-directional current source is needed so as to exploit the Peltier device’s heating and cooling phenomenon: one face of the device heats up when current flows in one direction and the same face cools down if the current through it flows in the opposite direction.

The idea is to use transistors as a voltage to current amplifiers. The op-amp is used to complement the same purpose: it provides the initial voltage signal at the base of the transistor so that the transistor may operate at such ADC-biased base voltage configuration where current to voltage amplification takes place. Another consideration is the fact that the DAQ (we use DAQ as out input voltage source) only provides a certain amount of output voltage. Keeping this practical constraint view, the op-amp or any voltage to voltage amplification device becomes a necessary part of the circuit.

Mainly, following components have been used:

  • Dual polarity power supply
  • 741 Op-amp
  • Resistors of various values as indicated in the diagram above
  • BJT BD 243C (NPN transistor)
  • BJT BD 244C (PNP transistor)
  • Betatherm NTC thermistor 2.2k3A359I
  • NI-USB 6001
  • Peltier device labelled as LOAD in the above diagram