Junebug bug w/ USART?

[.W4GNS]

Yes sir, some folks do and a few actually read the manual and datasheets

Actually I wounder dose any one ever look at the samples. There real helpful

 

[Pommie]

Plan to use a 1440watt Hot water tank element, a pump, and PID controller (home-built would be cheaper and more sataisfyting. Using the DS18B20 if I read all the 12 bits for temp, then the temp will display down to .065 instead of .5

You don't seem to understand what accuracy means.

Mike.

 

[be80be]

MrDeb is this what your looking for how to get a 25.C on the LCD

LCD.Write(DecToStr(TempA),".C ",DecToStr(TempB),".C ")

That's it.

 

[MrDEB]

Yo Pommie, nice to hear from you again.
Am I missing something concerning accuracy?
Plan is to try an build a PID using a PIC and a temperature sensor. Maybe the DS18B20 is not the desired sensor?
Contemplating maybe a thermocouple but can it be as accurate.
I only want a max temperature fluctuation of 1 degree.
The heater, pump etc are ideas from this example https://seattlefoodgeek.com/2010/02/diy-sous-vide-heating-immersion-circulator-for-about-75/
They are using three heaters. Found one - 1440 watt 110v hot water tank element is $10.
Enlighten me if I am going down the wrong path.

 

[be80be]

Type T thermocouple are .1%

 

[MrDEB]

.1% is better that .5 for sure but .0625 is better? at least that"s what the data sheet says on the DS18B20?
Digital output = 25.0626C = 0000 0101 1001 0001 or 0191h
maybe I is reading the data sheet wrong (read interpreting)?
Using the thermocouple would require say temperature compensation ic?

 

[be80be]

Have a look your missing something 25 could be 24.5 0r 25.5

 

[MrDEB]

Maybe I am missing something?
.5 degrees C = 32.9 degrees F
1 degree C = 33.8F
.9 degrees F accuracy
I assume IF you are reading all 12 bits

 

[ghostman11]

Hi Mr DEB, forgive me if i am wrong, but from reading this thread i think you have a slight mix up with the meaning of terms. accuracy isnt the same as resolution (number of bits).
the sensor your using is pretty much the same as the ones i use. the quaoted accuracy is 0.5c. wich basicaly means if you read the sensor and it says the temp is 32.5c then the real tempreture could actualy be 32c or 30c, resolution is the number of digits after the decimal point. for example you may have the temp displayed as 32.542457 but again the reality is the actual tempreture your measureing could be anything between 32c and 33c.
now in real life it dosnt matter much, i use theese sensors for running high end incubators where temp fluctuation matters a great deal, but i only read upto 2 decimal places i dont think there is any gain in reading more. also keep in mind you dont actualy read the sensor constantly. by this i mean there is always a delay of between 750 ms and a second. so you never actualy gets readings from the sensor like 32.532c 32.533c 32.534c what your more likely to get is a reading of 32.5 32.7 ect etc. bottom line is the reading MAY or MAY NOT be plus or minus 0.5c from the actual tempreture.
hope this helps

 

[MrDEB]

after some research I am under the impression that a thermocouple may be a better choice as the resolution is better.

 

[be80be]

"ghostman11

now in real life it doesn't matter much, i use these sensors for running high end incubators where temp fluctuation matters a great deal

If ghostman11 can hatch a egg and keep the temp right I'm sure you could cook one to 140 or good enough to eat and say it was the best you ever ate.

 

[ghostman11]

another thought that occured to me. i keep tropical fish i only have 2 aquariums theese days but i like Discus fish and breed them, they are notoriously hard to keep and breed well there water has to be spot on, it has to be the correct PH and hardness as well as a host of other parameters.
so whats this got to do with cooking?? well i heat the aquariums with normal aquarium water heaters they are the bog standard heaters and they keep the water at exactly 83f on occasion it can vary to 84f or 82f but it rarely moves. this is probaly due to the facy that a liquaid takes a while to heat up and loes heat. dont try and over engineer a heater for a liquid you will just be wasteing money!

 

[be80be]

I looked at a bunch of pid controllers where I worked they make nylon and raylon and A lot more. Heat had to be good. But to get a 140f dead on it takes manual
calibration.

If you put a gallon of water on the stove put a thermometer slowly bring the water up to 140F I bet you can keep it there with little or no trouble.

This is easier then you would think.

Now put the same gallon of water on there and forget about it burner on high when it hits 140F turn it off this would need pid to keep it where you want it.

The first is how my wife did it always good and never burnt any thing

The last is me some time need a trash can and start over

MrDeb I wonder it that's what happen