Hello,
My name is Dave and I am a student at SDSU. I am not an engineering major, so I cant speak the engineering language too well, but I have taken level 2 college physics and 2 years of chemistry.
I origionally wrote this question to the esteemed Tim Wescott, who offered some great advice and suggested that I post my question up here. I believe he will post his origional response up here as well.
With that said, I am trying to build a heater that uses a 35w halogen light bulb as the heating element to heat an object. The thermocouple sensor I am using is a type "J" sensor. I was wondering if you could offer some advice on how I could regulate the temperature of my light bulb with a digital PID controller.
Essentially I want the PID to surve as a dimmer switch that smoothly increases or decreases the power to the light bulb in ordere to have the object maintain a set temperature.
Since the temperature of the object will be changing temperatures due to external forces, I want the light bulb to remain on for the duration of the heating. And because I am looking for accuracy, I don't want to use the basic on-off style regulation. I was hoping to find a way to use the differential integral method (PID) of precisely giving power to the bulb.
However, in order to do this, I have been told that I need a very expensive and complicated PID device that has a linear output (0-5V) or (2-20mA) and then build a DC power amplifier that can convert the DC low power signal to a 35 watt output, and/or use an SCR. This sounds way too awkward and expensive, and I was wondering if anyone knew of a more simple and sophisticated way of accomplishing my task? I would even go as far as building the circuit myself if knew what components to use!!
Ultimately, I just want the device to be as accurate and consistent as possible. There are a million PID controllers out there, and I am just having the trouble of figuring out what I need to make it work as a dimmer with a 35w halogen light bulb.
Can anyone answer to this call???
Respectfully,
Dave Deriso
Overview:
Input: 110v AC (house) Sensor: Type "J" Thermocouple Controller: hopefully PID that can eventually function as a dimmer Element: 35w halogen lamp Interface: 2 line lcd with current and set temp plus ability to set new temperatures easily with up, down, and set buttons for the lcd display Budget: