Author Topic: Question hygrometer (Read 2449 times)

micksmelanie · « **on:** July 01, 2020, 12:06:11 pm »

Which hygrometer thermometer is more accurate efficient? analog or digital? i need help choosing a good cheap hygrometer from Aliexpress

digital some use Cr2032 battery others use LR44 battery

GlennSprigg · « **Reply #1 on:** July 01, 2020, 12:23:42 pm »

Ermmm... Green leafy hydroponics in the home is not my 'forte'

micksmelanie · « **Reply #2 on:** July 01, 2020, 08:24:42 pm »

rdl · « **Reply #3 on:** July 02, 2020, 02:57:26 am »

Most cheaper hygrometers are going to use an electronic sensor and you pretty much have to go on faith that the specification given is reasonably accurate. Calibration or verification of such a device is a bit of a pain.

Couple of years back I grew some lettuce on my kitchen counter and some nice bell peppers in the bedroom closet. All done hydroponically, no hygrometer required.

micksmelanie · « **Reply #4 on:** July 02, 2020, 01:28:14 pm »

any hygrometer is precise?

Ysjoelfir · « **Reply #5 on:** July 02, 2020, 01:41:38 pm »

Yes. All of them. To some extent.

micksmelanie · « **Reply #6 on:** July 02, 2020, 03:08:32 pm »

the precision humidity and temperature sensors used in cheap digital hygrometers also have the same efficiency as expensive hygrometers?

Benta · « **Reply #7 on:** July 02, 2020, 08:50:40 pm »

Quote from: micksmelanie on July 02, 2020, 03:08:32 pm

the precision humidity and temperature sensors used in cheap digital hygrometers also have the same efficiency as expensive hygrometers?

Yes. Of course. Just as a cheap alarm clock is just as precise as a Breitling chronometer.

Ysjoelfir · « **Reply #8 on:** July 02, 2020, 08:52:01 pm »

Efficiency as in... they work? Yes, sure.
Cheap and precision is also something that just doesn't fit.

RoGeorge · « **Reply #9 on:** July 02, 2020, 08:56:24 pm »

Buy a passive hygrometer. No battery ever, it just sits there and works.

micksmelanie · « **Reply #10 on:** July 03, 2020, 12:05:38 am »

on aliexpress there are many cheap hygrometers which one would be more accurate in measuring humidity and temperature?

https://www.aliexpress.com/wholesale?catId=0&initiative_id=SB_20200702160524&isPremium=y&SearchText=higrometer+thermometer

Gregg · « **Reply #11 on:** July 03, 2020, 12:29:30 am »

How about old school wet bulb / dry bulb with a chart something like this: https://www.amazon.com/Taylor-Precision-Permacolor-Mercury-Free-Hygrometer/dp/B002E0EH3A
Low maintenance, no batteries and no calibration necessary; just use distilled water to keep deposits to a minimum

micksmelanie · « **Reply #12 on:** July 03, 2020, 12:56:07 am »

a model sold on aliexpress

Ysjoelfir · « **Reply #13 on:** July 03, 2020, 06:06:19 am »

I'd choose this one https://de.aliexpress.com/item/32850539410.html?spm=a2g0o.productlist.0.0.9188261fO63SP6&algo_pvid=8b5ef314-1c35-4a41-9f00-b7b3df7974fb&algo_expid=8b5ef314-1c35-4a41-9f00-b7b3df7974fb-1&btsid=0ab6d67915937563598901326e6e53&ws_ab_test=searchweb0_0,searchweb201602_,searchweb201603_

steve30 · « **Reply #14 on:** July 03, 2020, 10:27:26 am »

I'd suggest one of these:

https://pt.aliexpress.com/item/32865734504.html?spm=a2g0o.productlist.0.0.473331a9XoSApp&algo_pvid=b63b661f-7361-4204-85fc-31c30ca18e10&algo_expid=b63b661f-7361-4204-85fc-31c30ca18e10-22&btsid=0be3764515937719199577390e340a&ws_ab_test=searchweb0_0,searchweb201602_,searchweb201603_

They're cheap and work fine.

Ysjoelfir · « **Reply #15 on:** July 03, 2020, 11:15:43 am »

To be a bit more serious: thats also an option. I use one of those in the lab and they don't differ that much from my Lambrecht 252 - only difference was the price and that the cheap one is easier to read. Sort of.
But since micksmelanie is very concerned about longevity an analog one might be the better choice, one like that, used eg. in humidors to keep the moisture of the cigarrs constant comes to mind:
https://de.aliexpress.com/item/32914628508.html?spm=a2g0o.productlist.0.0.2c1e5ccbk4ovRZ&algo_pvid=c9ef7ff7-2589-45e6-aeb3-b9f9563f422a&algo_expid=c9ef7ff7-2589-45e6-aeb3-b9f9563f422a-1&btsid=0ab6d67915937749006011703e7d4e&ws_ab_test=searchweb0_0,searchweb201602_,searchweb201603_

micksmelanie · « **Reply #16 on:** July 03, 2020, 12:32:14 pm »

Quote from: steve30 on July 03, 2020, 10:27:26 am

I'd suggest one of these:

https://pt.aliexpress.com/item/32865734504.html?spm=a2g0o.productlist.0.0.473331a9XoSApp&algo_pvid=b63b661f-7361-4204-85fc-31c30ca18e10&algo_expid=b63b661f-7361-4204-85fc-31c30ca18e10-22&btsid=0be3764515937719199577390e340a&ws_ab_test=searchweb0_0,searchweb201602_,searchweb201603_

They're cheap and work fine.

I already had this hygrometer but it didn't have this cable, is this version with a cable better than the version without the cable? I will put it in the bedroom and living room

steve30 · « **Reply #17 on:** July 03, 2020, 01:07:30 pm »

The cable just means that you can measure the humidity in one place, and put the display in another place.

For example, put the sensor in a box, and have the display visible outside the box.

There will be no difference in accuracy.

micksmelanie · « **Reply #18 on:** July 03, 2020, 01:46:40 pm »

Quote from: steve30 on July 03, 2020, 01:07:30 pm

The cable just means that you can measure the humidity in one place, and put the display in another place.

For example, put the sensor in a box, and have the display visible outside the box.

There will be no difference in accuracy.

digital and needle hygrometer have the same precision?

tggzzz · « **Reply #19 on:** July 03, 2020, 02:47:16 pm »

Quote from: micksmelanie on July 03, 2020, 01:46:40 pm

Quote from: steve30 on July 03, 2020, 01:07:30 pm
The cable just means that you can measure the humidity in one place, and put the display in another place.

For example, put the sensor in a box, and have the display visible outside the box.

There will be no difference in accuracy.
digital and needle hygrometer have the same precision?

Which bit of steve30's answer did you not understand?

If that sounds petulant, consider a moderator's question to you at https://www.eevblog.com/forum/chat/moisture-and-electronics/msg3117256/#msg3117256

steve30 · « **Reply #20 on:** July 03, 2020, 02:52:14 pm »

Quote from: micksmelanie on July 03, 2020, 01:46:40 pm

digital and needle hygrometer have the same precision?

Yes.

ocw · « **Reply #21 on:** July 03, 2020, 04:14:28 pm »

Typical electronic hygrometer sensor accuracies range from 2 - 5%. Often that accuracy is only valid over a portion of their measurement range. Accuracy suffers at the extremes.

A reasonable cost (though far from the least expensive) option is a Renesas SDAH02 evaluation kit using a Renesas HS3001. The evaluation kit has the sensor mounted along with a display, battery holder and some switching, but no case. A simple measurement change over time display is available. The accuracy is +/-1.5% for humidity and +/-0.2 degrees C. Most less expensive options do not have that accuracy. It has overkill resolution: 0.01% and 0.01 degree. Its limitation is not having a remote sensor, although the SDAH02's sensor could be detached and connected via a cable. I have not tried that modification. For more information see: https://www.idt.com/us/en/document/man/sdah02-kit-user-guide

I have a SDAH02 mounted in a ventilated case and use it for air measurements at the same time that I am taking soil moisture and temperature measurements at a variety of depths using other sensors.

micksmelanie · « **Reply #22 on:** July 03, 2020, 07:19:06 pm »

low cost would you recommend the electronic hygrometer or the needle hygrometer?

ocw · « **Reply #23 on:** July 03, 2020, 07:54:35 pm »

Quote

low cost would you recommend the electronic hygrometer or the needle hygrometer?

Compare their accuracy specifications. If none are listed that generally means that they are not proud of those figures. Even if good accuracy figures are shown, make sure that they are reliable numbers.


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Author Topic: Question hygrometer (Read 2449 times)

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