Digital Temperature Controller

This is a very useful digital temperature controller where it can control a device within a user define two temperature set points very accurately.

Features

*User define two set points (lower & upper limits)
*0.5C accuracy with a temperature range 00.0C to 99.5C
*Built in software hysteresis for stable operation
*Temperature limit indicators
*Easy menu system for adjust & view temperature

Operation

If the user sets the lower temperature limit to 27.0C & sets the upper temperature limit to 39.5C, the relay will be “ON” if the current temperature is in between these set points. And whenever the current temperature goes above or below of these temperature limits the relay will goes “OFF” & waits until the current temperature comes between the two set points.

How to set the lower & upper limits?

Press the “MENU” button. You will see the lower limit indicator will light & shows the lower temperature. Press the “ADJUST” button to change the lower set point to a desired value.

After setting lower set point press the “MENU” button & it will light the upper limit indicator & displays the upper temperature. As above press “ADJUST” button to change the upper set point.

After adjusting set points pressing the “MENU” button will direct you to come to the normal mode to display current temperature & you will see the decimal point is blinking in this mode & is ready to do the task you have already assigned.

Note: LM35 works well with temperature starting from 2C onwards.Getting below 2C will require additional diodes in the hardware itself.

Schematic