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Tuesday, August 9, 2016

WE Project: Peltier Temperature Controller

I spent the weekend learning about TEC controllers and Peltier elements and attempted to build a basic Peltier controller. On the electronics side I used a 2 channel buck converter as shown in the simple schematic. For the inductors i used a pair of 230uH coils,  2 x 3A Schottcky diodes and identical pair of n Channel switching MOSFT I found in my inventory.

I used a small Peltier element (7108AC) with these characteristics: -dTmax = 70°C, Qmax=43.1W, Umax = 8.8V, and Imax= 8.5A 

The overall design is based on Information provided by this website,  The Peltier device is what you would expect with, An Aluminum disk  fixed to the cold side of the peltier element a small Heatsink and a 24V Fan as seen in the photo are mounted on the warm side of the peltier. All Is built inside a cubic tin can.

To generate the PWM , first I used a microcontroller and then I experimented with a PWM IC (TL494)
The setup includes a step-up converter for the Fan and a linear regulator for the 5v Fan to cool the mosfets.

In the first test I could cool the metal Plate to 7.5 °C consuming about 8.5 W at Room temperature of 25°C