led temperature/humidity addon

**cbiblis** · 24th November 2009 05:23 AM

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.

**cbiblis** · 24th November 2009 06:02 AM

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.

**mneary** · 24th November 2009 07:28 AM

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** · 24th November 2009 07:36 AM

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

**mneary** · 24th November 2009 07:47 AM

And here's the screen capture in PNG.

**cbiblis** · 24th November 2009 07:49 AM

That is better. How did you transfer from sch to png?

**mneary** · 24th November 2009 07:50 AM

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** · 24th November 2009 07:54 AM

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.

**mneary** · 24th November 2009 07:54 AM

Originally Posted by cbiblis

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.

**cbiblis** · 24th November 2009 09:18 AM

Originally Posted by mneary

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** · 26th November 2009 12:13 PM

Originally Posted by mneary

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.

**mneary** · 27th November 2009 09:30 AM

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** · 28th November 2009 09:09 PM

Originally Posted by mneary

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?

**mneary** · 29th November 2009 12:06 AM

Positive to cathode, negative to anode.

**cbiblis** · 29th November 2009 10:16 PM

Originally Posted by mneary

Positive to cathode, negative to anode.

Are you telling me to piggy back the diode?

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