Humidity Indicator Cards

A pack of humidity indicator cards arrived from far-off Pennsylvania and work just about like you’d expect.

The silica gel really does pull the interior of the Basement Safe down below 15%:

Humidity Indicator card - 10 percent
Humidity Indicator card – 10 percent

The dehumidifier struggles mightily to keep the rest of the basement around 50%:

Humidity Indicator card - 50 percent
Humidity Indicator card – 50 percent

They’re not dataloggers, but I can now keep an eye on more locations…

8 thoughts on “Humidity Indicator Cards

  1. Have you ever looked at Dallas Semi’s thermochron’s with the humidity option? Pricey, but self-contained and runs for years.

    1. Pricey

      Those things run $100 each: you have obviously mistaken my toy budget for a suitcase stuffed with unmarked currency! [grin]

      On the other paw, the Hobo datalogger equivalent to the ones I’m using is around $130.

      If I were in the market, I’d prefer the Dallas / Maxim button: their data format seems well-documented and isn’t locked to a goofball Windows-only program.

      There was an unsuccessful Kickstarter for a nominally cheap temp/humidity datalogger, but … it’s a specialized market.

      1. I’ve worked with the Dallas “one-wire” protocol (I’m pretty sure their buttons all use it), it’s pretty simple to bit-bang, at least on a sane processor. In my case, I had to do it with a DSP that didn’t really grok anything other than its 36-bit words, so it was a little tougher. Somewhere I have a couple of the button-to-DB25 adapters, I saw ’em at a hamfest and the seller had no idea what they were.

  2. You can find them for a little less than that ($85 in onesies – $50 in K-sies) but, yes, they are pricey! I have their non-hygro brothers currently on a “mission” (as Dallas likes to call the data-collection runs) from China. They are really nice – I was first introduced to the iButtons when I got a Segway, and later incorporated 1-wire products on a few designs I’ve worked on over the years. I’ve used Hobo’s before, but the iButtons run longer on battery than the Hobo’s IIRC. The smaller iButton form-factor (about a piece of a mentos candy) is an extra bonus.

    1. the iButtons run longer on battery than the Hobo’s IIRC

      And when the battery goes flat, you toss the whole iButton and start over; I like the size & shape, but not that part. Of course, the size & shape dictate the battery capacity & disposable lifecycle: they solve different problems than the ones I have.

      currently on a “mission”

      Love the terminology: HOBOware has you “deploy” their loggers. Cuing Secret Agent Man on Turntable 2…

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