SensorPush

[AcousticDreams]

I find something new on the forum everyday to investigate! LOL
This item sounds great. I have a few questions:

1. Can you only monitor from Phone? Or can you monitor from Computer as well? I am a caveman and have flipphone. Yet oddly...very proficient on my Mac.

2. I am in the need of more hydrometers and this sounds great especially since one of my needs is to be able to Calibrate.
* So my question is, how do you calibrate this unit? Can you just tweak a dial and bring it up to the the correct Humidity level? I use multiple weather stations and place my hydrometer outdoors and then adjust to the reading of my nearest weather station.
Or is there a problem with this technique?

3. After reading this post I immediately looked up SenorPlush and noticed that Oasis has a new product similar?
Oasis OH-31 HT Tracker
It may just be a repackaged SenorPlush...but it has an extra eye? I have an email into Oasis.

4. Where do you guys place your sensor? And how do you adhere your sensor in the case?
As we all know...adhering a hydrometer can be an issue. Velco and the likes do not often stick to thick materials. Clips aren't great for better cases.

Found a good way for my Oasis by simply folding over cloth in the compartment case. This holds it in very tightly.
But remote sensoring would be idea especially for a couple of guitars that I do not play as much.

[Dbone]

Originally Posted by fazool

I tried the only option I could find (was ineffective) and haven ye to find a solution that will push text alerts out to my phone while I'm away.

I want to find something (don't even need battery) that connects to WiFi and sends limit alerts to my phone.

I know there are industrial and laboratory versions (I use them at work) but I want a simple home solution in case I'm away and my humidity dips too low.

Can't find that solution - might try building an Arduino-based system,

This is a solution. As I said above, they are soon adding email alerts when you have the gateway in their ecosystem running. Not a text message, but close enough, no?

[justonwo]

Originally Posted by ljguitar

Hi Db

Do you think they will protect a guitar better than a conscientious person who uses a sponge-in-a-zip-lock humidification system for his/her case, or a room humidifier for others?

Belt and suspenders. I suppose if you are worried about under-humidification (not the only concern, as you know), then if you’re really on top of things all the time and keep that sponge damp I suppose you don’t NEED the sensor. But it adds an extra layer of protection to alert you if you have a slip in conscientiousness. The system also allows you to study data and cause/effect relationships like, for example, how long that damp sponge will last you.

Given the cost of luthier built instruments, it seems like a good use of funds to me. But maybe not for you?

[Dbone]

Originally Posted by Knives&Guitars

I find something new on the forum everyday to investigate! LOL
This item sounds great. I have a few questions:

1. Can you only monitor from Phone? Or can you monitor from Computer as well? I am a caveman and have flipphone. Yet oddly...very proficient on my Mac.

2. I am in the need of more hydrometers and this sounds great especially since one of my needs is to be able to Calibrate.
* So my question is, how do you calibrate this unit? Can you just tweak a dial and bring it up to the the correct Humidity level? I use multiple weather stations and place my hydrometer outdoors and then adjust to the reading of my nearest weather station.
Or is there a problem with this technique?

3. After reading this post I immediately looked up SenorPlush and noticed that Oasis has a new product similar?
Oasis OH-31 HT Tracker
It may just be a repackaged SenorPlush...but it has an extra eye? I have an email into Oasis.

4. Where do you guys place your sensor? And how do you adhere your sensor in the case?
As we all know...adhering a hydrometer can be an issue. Velco and the likes do not often stick to thick materials. Clips aren't great for better cases.

Found a good way for my Oasis by simply folding over cloth in the compartment case. This holds it in very tightly.
But remote sensoring would be idea especially for a couple of guitars that I do not play as much.

To my knowledge you need iOS or Android...so phones or tablets...I do not believe a PC helps you much with this product. You could contact SensorPush directly to confirm that they do not have PC support, but I don't believe they do.

http://www.sensorpush.com

Never saw that Oasis product...Interesting...Doesn't sound like it is quite as sophisticated as the SensorPush in that it does not appear to have a gateway unit that can allow you to check status and get alerts from anywhere in the world over the Internet. If you don't care about that feature then I suppose it could be fine. The Sensorpush can run like that too though without the gateway, and it is essentially the same price. Advantage is that it gives you the option to add the gateway at any time should your requirements change. Also, its software is really good.

The calibration on the SensorPush sensors is done from within the Android or iOS app associated with the product. To my knowledge the absolute best way to calibrate is using the Boveda 75 RH calibration kit. Apparently you can also do it yourself by making an appropriate water and salt solution using basic table salt...There are videos out there on how to do it...The Boveda kit is certainly less hassle.

I personally will have one sensor in my guitar room where I do most of my practicing, and 2 in the case when the guitar is stored in that same room (one at the headstock and one at the sound hole). As for how I am mounting them, I do not yet know as I don't have my new guitar yet...coming in September...I'm just getting things ready and setup ahead now...The SensorPush sensors have a little hole in them that I presume you could loop at string through...If that could be helpful for mounting...

The guitar I have right now is all laminate and super cheap so I haven't done much of anything for humidity...I don't even have a proper case for it ;-)

[justonwo]

I went whole-hog on on SensorPush units. I have about 15. I noticed most of them were in the 60s, when the ambient RH around here has been in the low 50s for ages.

So I calibrated two units at 43% (saturated potassium carbonate). My cheap Oasis hygrometer hit 42%. One SensorPush read 51% and the other 48%. So I calibrated with the offset tool. Then I put all three sensors in a saturated NaCl system, which equilibrates at 75%. Oasis read 71%. SensorPush units were 65 and 64%.

Seems like these SensorPush units have pretty lousy accuracy.

[sinistral]

That’s odd. I have 10 sensors currently, with mini Oasis hygrometers in each case to compare against. They’re all within 1-2% of each other (using either Boveda or D’Addario Hydropaks). You might want to contact SP’s customer service.

[justonwo]

Originally Posted by sinistral

That’s odd. I have 10 sensors currently, with mini Oasis hygrometers in each case to compare against. They’re all within 1-2% of each other (using either Boveda or D’Addario Hydropaks). You might want to contact SP’s customer service.

How long have you had yours?

[KevinH]

Originally Posted by sinistral

That’s odd. I have 10 sensors currently, with mini Oasis hygrometers in each case to compare against. They’re all within 1-2% of each other (using either Boveda or D’Addario Hydropaks). You might want to contact SP’s customer service.

Same here. I have 3 SensorPush and several WirelessTags. All read pretty close to one another, and I've never seen them out of calibration by more than 1% or so. I've had mine for a couple years.

Possibly batteries getting low?

[sinistral]

Originally Posted by justonwo

How long have you had yours?

Only about five months, but they’ve been pretty stable/consistent during that time. Haven’t had to change batteries yet. It would be nice if the app had a battery life indicator.

[justonwo]

Originally Posted by sinistral

Only about five months, but they’ve been pretty stable/consistent during that time. Haven’t had to change batteries yet. It would be nice if the app had a battery life indicator.

Well, it does actually. The app tells you the battery voltage and warns hours when it drops below 2.3 VDC. The nominal new voltage is 3.0 VDC.

It’s odd because the sensor with the 3.0 VDC battery it pretty inaccurate, too. Maybe the voltage indicator isn’t accurate. One is those sensors is two years old. I ordered new batteries earlier today just to rule that out.

[justonwo]

Edited: Added two new sensors

So I've been busy collecting data on my SensorPush units, most of which I bought over a year ago. I'm measuring against the following:

1) Boveda 69% in a sealed bag
2) Boveda 49% in a sealed bag
3) Saturated K2CO3 solution, sealed in a bag (43% RH)

I'm also using my Honeywell and Oasis digital hygrometers for reference.

--------------Boveda 69%---Boveda 49%------K2CO3 (43%)
Honeywell-------68%-------------51%
Oasis-------------66%-------------52%-------------40%
SP #1------------69.7%-----------57.8%-----------50.3%
SP #2------------69.6%-----------58.1%-----------49.4%
SP #3------------72.2%-----------62.9%-----------56.3%
SP #4------------67.2%-----------55.9%-----------47.5%
SP #5------------68.3%-----------57.7%-----------49.5%
SP #6------------71.5%-----------60.8%-----------53.6%
SP #7 (brand new, latest gen)----------------------46.7%
SP #8 (brand new, latest gen)----------------------47.2%

The sensors are all generally in the right range with the Boveda 69%, but are wildly off with the other two (lower) RH standards. Looks like the slope of the calibration curve is really funky. If you "calibrate" the sensors at low RH, then they aren't accurate at high RH anymore.

The thing that tipped me off is that my guitars have been in the low to mid 60s RH for months, and the ambient RH here in the Bay Area is almost always high 40s to low 50s.

The folks at SensorPush were kind enough to send me two new units to try, but these old units are wildly inaccurate. (I have tried changing the batteries, by the way. No difference.) And, just for clarity, all units were allowed to equilibrate for a couple of days. I wait until the plot of RH vs time has converged on a steady reading.

[KevinH]

Wow, that is surprising. They're not only outside their accuracy range of the standard, but with each other as well for the most part. I'll be interested to hear how the new units stack up.

How do the temperature values compare with each other? I'm wondering if the sensors actually measure absolute humidity then convert that to relative using the temperature.

[justonwo]

Originally Posted by KevinH

Wow, that is surprising. They're not outside their accuracy range of the standard, but with each other as well for the most part. I'll be interested to hear how the new units stack up.

How do the temperature values compare with each other? I'm wondering if the sensors actually measure absolute humidity then convert that to relative using the temperature.

They're all room temperature, so 68-70°F. Sadly, although the new units are better, they aren't that much better. The two brand new units stabilized at 46.7% and 47.2% in the K2CO3 environment. I just moved them over to the Boveda 49%. I guess a few points off isn't too bad. We'll see how accurate they are using the Boveda 49% and 69% references. A calibration offset is not a big deal, but if the slope of the calibration curve is wrong, the sensors are more or less worthless.

[UncleJesse]

Oh man that isn't good...I need these SP to work properly I count on them in the winter.

[KevinH]

Originally Posted by justonwo

They're all room temperature, so 68-70°F. Sadly, although the new units are better, they aren't that much better. The two brand new units stabilized at 46.7% and 47.2% in the K2CO3 environment. I just moved them over to the Boveda 49%. I guess a few points off isn't too bad. We'll see how accurate they are using the Boveda 49% and 69% references. A calibration offset is not a big deal, but if the slope of the calibration curve is wrong, the sensors are more or less worthless.

Bummer. The humidity set point for K2CO3 is 43.2±0.3, and the quoted accuracy of the SP is ±3%. Closer, but still out of spec. The new ones are certainly close enough for guitar maintenance, but it's still kind of disturbing. Has Sensor Push hasn't had any other suggestions?