Power Drive Circuit Methods
PID stands for Proportional - Integral - Derivative control. These are mathematical terms that anyone
without an engineering degree probably is not familiar with. There are many places where you can find
information on this online if you want to know more. However there is one aspect of the common PID
temperature controller I would like to discuss as it has material implications for temperature control
applications.
The picture on the right shows a test setup which controls a small 20 watt light bulb. Because the bulb
only draws less than one ampere of current it can be operated without a heatsink. This is one of my
test setups. When in operation you will observe 3 notable points:
1) The temperature of the bulb starts off at room temperature
2) The temperature of the bulb moves up to match the set point of the controller
3) The bulb does NOT stay on constantly and dim or brighten depending on how much
it needs to cool down or warm up but rather pulses on for various amounts
of time.
4) Since the controller is set to 120 degrees Fahrenheit the bulb does not stay on
much. Most of the time it is off. The hotter you set the controller the longer
the heating element of whatever type, in this case a light bulb, stays on.
PID Light Bulb Controller Movie
