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led temperature/humidity addon

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cbiblis

New Member
I have designed and built a thermostat for my incubators. It works awesome. Just recently with help from MikeIM i have incorporated a motor control for the egg turner. My next addition is to add a led humidity sensor displayed in a blue 4 number 7 segment and a temperature display in red 4 number 7 segment led. I want to stress " I DO NOT WANT A LCD DISPLAY" I want led because they are viewable from a distance and i like the colors. I would appreciate any help that you could give me. I also don't have a programmer so advise on one that i should have to program multiple types of chips would also be appreciated.

I have attached the schematic for what i am currently using.
 

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  • new thermostat.jpg
    new thermostat.jpg
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cbiblis

New Member
actually i am using a 10m on the r7 for now. I am getting a .3 degree hysteresis but i am also getting a relay chatter. Probably a 4 to 5 click chatter. I am waiting for my new resistor assortment to try out a 9.09m to stop the chatter. If i can get .5 degree variance between cycles without the chatter i will do cartwheels in the front yard.
 
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mneary

New Member
It's a waste of your time posting fuzzy jpegs. We can't read them.

You just have to tell PAINT you want PNG in the drop down menu on the 'save as' window.
 

cbiblis

New Member
I was using a screen shot of eagle. Here is the eagle sch file to view.
 

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  • new thermostat.zip
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mneary

New Member
Ah, to reduce the relay chatter, R7 should be decreased. This does decrease the precision.

Maybe it would be more stable if you put a 100uF cap from the pot pin 1 to GND.
 

cbiblis

New Member
I could try that. I will build it on the bread tomorrow to see if that will fix it. Problem is that it will work on some boards and not on others.
 
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mneary

New Member
That is better. How did you transfer from sch to png?
Screen capture.
Open Paint.
ctrl-V, esc
select desired area
ctrl-C
ctrl-N (new document) answer 'no' to save
ctrl-V, esc
save-as
choose directory. choose name.
just below the name you typed, click in the window that reads JPG, and select PNG.
 
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cbiblis

New Member
Ah, to reduce the relay chatter, R7 should be decreased. This does decrease the precision.

Maybe it would be more stable if you put a 100uF cap from the pot pin 1 to GND.

By the way if this pans out i will have to add to your rep with " He's a super genius"
 

cbiblis

New Member
Ah, to reduce the relay chatter, R7 should be decreased. This does decrease the precision.

Maybe it would be more stable if you put a 100uF cap from the pot pin 1 to GND.

I put in a 100uf cap in like you said and it didn't fix the issue. i even dropped the value of the r7 to 4.7m and this one specific thermo continues to chatter. All of my other identical circuits works with the original design without chatter. I did have to drop the r7 on one of them to 6.8m to stop the chatter. 6.8m widens my variance to 1.5 degree differance. I assume i would get a much wider valiance if i was forced to use the 4.7m.
 
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mneary

New Member
Is the voltage across ZD1 stable? Variance there could also cause problems, although the sensor circuit is ratiometric and should be immune to most reference changes. Try the 100µF across ZD1.
 

cbiblis

New Member
Is the voltage across ZD1 stable? Variance there could also cause problems, although the sensor circuit is ratiometric and should be immune to most reference changes. Try the 100µF across ZD1.

Which side of the zener do i try it on?
 

cbiblis

New Member
Will pay for the help.

Ok, once again i need to finish this project. I am waiting for someone to help me so i can produce these thermostats for my incubators. I will pay for a working schematic, Eagle would be awesome but i can rebuild it from a emulator like tina. They have to be accurate to 1/10 of a degree and refresh every second. I will need the program for the chip as well. Run off of 12v or 120v and be able to calibrate. Thanks.
 
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