The team has plans to create a closed-loop feedback system to control the temperature produced by the Peltier unit. A robust way of adjusting the Peltier supply power is an essential piece of the temperature control puzzle.
Today the team completed a proof-of-concept circuit which adjusts the power the supply delivers based on a PWM signal. First, this circuit was used to adjust the brightness of an LED as a cheap and obvious way to determine that everything was working.
PWM-controlled LED intensity
Once it was determined that everything was in working order the Peltier unit was connected to the circuit. Adjusting the PWM signal dramatically altered the rate at which the Peltier heated up and cooled down. It was also determined that powering the Peltier with the square waveforms from the MOSFET unit did not significantly decrease its efficiency. This is great news since it means that an inductor and flyback diode won't be needed to smooth out the current supply.
Test circuit with Peltier and thermocouple
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