Digital Hygrometer

[Nrotik]

Quick question...I have a Little Havana digital hygrometer...When the temperature reads between 68 degrees and up it appears the humidity is accurate (65%-67%)...When the hygrometer reaches 67.9 degrees and below the humidty jumps immediately to 70%-73%....Is this accurate of what all digital hygrometers do?

 

[NullSmurf]

Just for shits and giggles, replace your battery. Observe again. If you still have the book, take another look. See if the accuracy listed, guessing +- 2%, is for a specific temp.

 

[McPhenius]

I have that model and I have not noticed that.

 

[NullSmurf]

I read up on the solid state devices used to sense relative humidity. This type of sensor is a relative of a diode. Most will operate at +/- 2% from 60 to 120 degrees F with virtually no drift. The constant is the supply voltage. As the battery declines, the operating voltage falls below threshold, the RH reading will also drop.

Going high based on a temp change of only a few degrees is something I can't explain.

 

[Fuscat]

I have one of these too. I have never noticed anything of what you describe with the temp, as mine has stayed pretty consistant in temp range +/- a couple of degrees. (usually 65d or pretty close) However the accuracy of the humidity reading is WAY off, as in 12%! And thats on fresh batteries out of the pack! It's my opinion that these are just not quality hygrometers. One of these days I will get around to replacing it. I know this doesn't really answer your question, but thought it might be usefull info..

 

[BlindedByScience]

I have three LH's and replace the batteries every year, just to be sure. Never seen anything like you mention. In fact, mine all salt test on the money and have been very consistant.

Be careful when you buy batteries; don't want to get batteries that have been on the shelf for a long time.....

Good Luck - B.B.S.

 

[NullSmurf]

Just to clarify since quite a few on here are geeks, the sensing device operates at less than a volt. The sensing voltage swing isn't much, usually less than .2 volts. The Radio Shack digital uses three AA batteries - big sucker at 7.5volt. The device most likely regulates to (uses) 3 volts giving it a great battery life.

My other two both use a single 1.5 volt button battery. I'd guess I have reasonable accuracy down till the battery drops below a volt. As the batter declines further, the display will look just like it does with a fresh battery, but will show a lower RH reading. I feel ok with replacing those button batteries about every quarter.

 

[emodx]

Just to clarify since quite a few on here are geeks, the sensing device operates at less than a volt. The sensing voltage swing isn't much, usually less than .2 volts. The Radio Shack digital uses three AA batteries - big sucker at 7.5volt. The device most likely regulates to (uses) 3 volts giving it a great battery life.

My other two both use a single 1.5 volt button battery. I'd guess I have reasonable accuracy down till the battery drops below a volt. As the batter declines further, the display will look just like it does with a fresh battery, but will show a lower RH reading. I feel ok with replacing those button batteries about every quarter.

Being a technician, I thought I was the electronics geek. What a nerd!

-Emo