Re: [DIYbio] Re: Making my own incubator inexpensively

On 04/23/2012 02:43 PM, Andreas Sturm wrote:
> Well, 2 Outputs for the LED indication of temperature, one ADC (you called it A2D).
> I use LM335 because it's very very easy to use. Of course, I could also use a PTC

That is $1 each in ones qty, so maybe you could use the inherent
temperature dependent volts in circuitry you already have. Often microcontrollers
take a known steady small current diode junction in the chip and arrange to
switch its voltage to the input of
the measuring ADC, with which you can use
a look up table of temperatures. A little more work in code and testing and
a whole dollar off! No big loss in accuracy for the range you care about.
Degrees C +/- 0.5 degree is easy. If there's not an internal convenient diode volts
to measure, you can add a diode and resistor to +DC power supply as your temp sensor
attached to a comparator/ADC input.

John

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