Incubators
Hello Tony,
I have made numerous incubators for zoology research. All have used the DS1620 or DS1629 and a simple PID to control either peltier devices or refrigeration compressors and heaters. I make the systems self contained with an LCD display and an UP, DOWN and ENTER buttons to change the setpoint. The LCD usually shows SetPoint, ActualTemp and sometimes time & date for units running any diurnal variation or executing a temperature profile.
I usually set the PIC hardware to stream ASCII characters out an RS-232 interface about once per 5~10 seconds giving setpoint, actual temperature, heating or cooling, PWM value for the heater/cooler and a timestamp.
There are a few tricks. With the DS162x clock line, I found I must terminate the clock line at the DS device end with 100 nF and 120 ohms to ground to stop ringing. The same for the data line but this seems less susceptible to noise. With this termination I can place the temperature sensor up to 5 metres from the electronics.
It also pays to make several readings and throw out any wild values, to have some hysteresis on the heat/cool changeover and a timer to prevent frequent short cooling bursts. Compressors will trip out on overload if you try to restart too soon before the high pressure side has had a chance to bleed the pressure off.
I gave Hyperterm the flick years ago - a heap of dingo droppings. I use TeraTerm for a much more robust and better terminal emulator.
HTH
BrianT
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