Cooking with HydraRaptor

2010-02-15 19:36:38

I needed to assemble some PCBs recently, so I set about making a temperature controller for my SMT oven.



First I had to replace the solid state relay on HydraRaptor.



Solid state relays are triacs with an optically coupled input, zero crossing switching and built in snubbers. I used it for controlling a vacuum cleaner when milling. It was massively overrated but for some reason it failed some time ago. I replaced it with a cheaper one and added a varistor across the mains input to kill any transients, as that is the only explanation I can think of for the old one's demise.





The next task was to write a simple graphing program in Python. I tested it by plotting the response of my extruder heater.



With bang-bang control it swings +/- 2°C with a cycle time of about ten seconds.

Here is the code for the graph: -
from Tkinter import *

class Axis:
def __init__(self, min, max, minor, major, scale):
self.scale = scale
self.min = min
self.max = max
self.minor = minor
self.major = major

class Graph:
def __init__(self, xAxis, yAxis):
self.xAxis = xAxis
self.yAxis = yAxis
self.root = Tk()
self.root.title("HydraRaptor")
self.last_x = None
frame = Frame(self.root)
frame.pack()
xmin = xAxis.min * xAxis.scale
xmax = xAxis.max * xAxis.scale
ymin = yAxis.min * yAxis.scale
ymax = yAxis.max * yAxis.scale
width = (xmax - xmin) + 30
height = (ymax - ymin) + 20