Looking for commercially available Temperature and or Humidity Sensors. Looking for the brands not the shopping stores. They could be digital or analog, however universal not specific to a single controller (I.e. HAI Temp/humidity Sensor only works with HAI controllers)
Checkout Veris senors. 4-20Ma, 0-10v, 0-5V
You need to be more specific. Are you looking for low level sensors like those made by Sensiron and Humirel which usually require additional electronics or are you expecting to find finished generic products. What type of output? Some are 0-5V, some are frequency, some are pulse width.
And, it's doubtful that HAI's sensors will >Looking for commercially available Temperature and or Humidity Sensors.
honeywell humidity sensor analog out
Peter Anderson has circuitry suitable for each type at
One can buy a single entire Honeywell temperature and humidity display with LCD display and case at a big box store for less than the price of the Honeywell humidity sensor alone in qty 25.
...Marc Marc_F_Hult
Omega is the go-to supplier of convenience for scientific and engineering markets and their equipment is priced accordingly. I use them very sparingly even for well-funded scientific research for this reason. Most everything they sell can be purchased elsewhere less expensively.
... Marc Marc_F_Hult
Basically looking for an low cost sensor either temp only, humidity only or combined, commercially available with specs and protocals.
At this point I dont have any requirements, just trying to see what is available, so I can determine how I can use them and implement them in a upcoming project for a client.
HAI's are fine sensors, but what does everybody feel about the cost, are they good, are they high or low?
I have no experience with HAI's sensors and thus no opinion as to whether they are "good".
But HAI modules are prohibitively expensive for my purposes and budget.
You write "sensor" without elaborating, but it is beginning to seem that what you want are _modules_ that can communicate rather than a bare sensing element.
Some very accurate temperature sensors (a silicon diode for example) cost
1/1000th of what I'd speculate that a HAI temperature module costs And calibrated thermistors, Dallas 1-wire devices, and LM34/35's cost on the order of US$1 and so enjoy about a 40-fold cost advantage compared to HAI (and Adicon and ELk and Aprilaire ) temperature _modules_.Of the humidity _modules_ that I know something about (HAI, Adicon, Aprilaire/Enerzone) and that are available (Elk's humidity sensors have not been released yet, but the temperature modules have) I've chosen to use Aprilaire's because: 1) they are industry standard for HVAC, 2) have a publicly available, simple ASCII protocol for communication over RS-485, 3) are compatible with my existing Aprilaire/Enerzone thermostats 4) which in turn are supported by all the common HA programs -- but not HAI which has its own stuff to sell.
HTH ... Marc Marc_F_Hult
Yes, Modules would probably be a better descriptor, thanks for the correction.
Thanks I will take a look at the Aprilaire version? Are there other companies outside of automation companies?
Humirel makes many sensors. Why recommend a specific one that is actually "non-stock" at Digikey, and is obsolete and so may never be back in stock? It has been replaced with the HTM1735 which costs $22.53 ea.
Marc Marc_F_Hult
companies outside of automation companies?
Aprilaire isn't really an "automation" company. They make HVAC equipment especially air cleaners, humidifiers and thermostats. For example they make humidifiers that Carrier sells. They purchased Enerzone several years ago. Enerzone made the Statnet communicating thermostats and Aprilaire adopted their design and, importantly their ASCII protocol over RS-485.
Honeywell makes bare humidity sensors (the HIH series that I've written about several times in comp.home.automation) and make/market a wide range of HVAC and security equipment.
Dunno what Honeywell may have in the way of a non-propriety communicating modules that isn't BACnet or LONWORKS -- the two principal open control protocols for building HVAC control automation. I assume that you don't want to go 'there' because of costs -- but building automation equipment (contrasted with home automation equipment) is not too different cost-wise from Crestron and other high-end HA.
... Marc Marc_F_Hult
On Thu, 5 Jan 2006 12:08:09 -0800, "Brett Griffin" wrote (with possible editing):
I was going to mention omega.com, but someone beat me to it! Another good source:
"Marc F Hult" wrote in
Why *IS* that? I was dismayed by the price and the restricted function of the ADI "Bobcat" line of temperature and humidity sensors. I see that Worthington has some very cheap sensors listed with their ADI, HAI and ELK offerings. I would ideally line to monitor temperature and humidity info for perhaps 20 different points in the house, with a wide array of temperatures, too (chimney temps, hot water heater, fridge, etc).
Monitoring temperature and humidity (as well as minute barometric pressure differences between rooms) from a lot of different locations *easily and cheaply* would be a very good way of making sure that everything in the house was functioning normally. With Bobcats, that will run me about $2500. :-( We'll see how well Jeff Volp's analog I/O -solution works for me when I get around to ordering the equipment. That depends on how well I predicted Christmas and travel related expenses.
-- Bobby G.
The Bobcat temperature node includes a power supply, an RS485 interface, an ADC chip (I think they use a PIC but it's been a while since I looked inside one), an enclosure and an LM34 temperature sensor.
The Bobcat humidity node includes all of the above but with a Humirel humidity sensor replacing the LM34. Humidity sensors are not cheap.
If you try to duplicate the design you will find that you really cannot build them and sell them through distribution channels for much less than what ADI charges.
If you already have some type of controller with ADC inputs and a power supply and a little knowledge you can DIY and save (if you conveniently ignore the cost of the controller). The cheap sensors need something like an SECU16 or other controller.
I think your plans are overkill but you should look at some of the one-wire interfaces which allow you to network lots of relatively inexpensive sensors (at least for temperature, RH is still not cheap). You still need some type of controller or PC to make sense of the data.
Humidity is really just two temperatures, dry and wet. Why not just get two temp sensors and a piece of cotton and some water? The formula is trivial.
A cool hack would be to use some ZigBee boards, the TI processor has a temperature sensor. Don't know what the prices are at hobby volumes.
I suggest that you close your pocketbook for now.
Let's back up a bit.
The Compleat Home Automation Controller needs to cause actions based on environmental thresholds (aka "events", "triggers") *AND* be capable of 1) measuring, 2) interpreting (performing calculations in order to define an event) 3) recording (storing) and 4) reporting continuously variable parameters such as temperature, pressure, illumination level and so on.
Most of the current crop of HA controllers and programs to a credible job at event-based control, and some are adequate for many purposes at measurement and using those measurements to define event thresholds.
But despite whatever comp.home.automation's well-intentioned "brand advocates" might lead folks to believe, the devices known in these parts as Home Automation Controllers (Adicon Ocelot, HAI, Elks etc) are mediocre or useless for general-purpose monitoring purposes for a variety of reasons.
The answer to your question of why these sensors cost so much lies in large part in that fact. If one needs only a few sensors, the add-on modules may be cost effective and have adequate performance for many purposes. However, as you have found, this approach becomes prohibitively expensive as you add more modules.
If one compares the capabilities of today's HA controllers with even
20-year-old environmental data loggers one is immediately struck by:1) Inadequate signal resolution (and in the case of some, precision) of the analog-to-digital converter (Adicon/Ocelot, Elk) or no analog input (HAI)
2) Inadequate data storage/retention.There are excellent, inexpensive solutions. Do check out
The key to good analog measurement is proper signal conditioning. I will post the design for the conditioned four-sensor pcb where I posted the
16-channel analog input multiplexor a couple of weeks ago.With the addition of a Dallas 1-wire DS2450 Quad A/D converter
More later ... Marc Marc_F_Hult
The _fundamental_ problem is that Ocelot is stuck with an 8-bit Analog to Digital converter which is a major obstacle to wide-range, high resolution temperature measurement. Adicon's expensive solution is have more smarts in the module and transmit the data digitally.
One better solution is to use an apppropriate logger/controller in the first place. Environmental data loggers have been around for decades. I don't know of a single one that is limited to 8-bit resolution -- for good reason.
The SECU16 is the same kettle of fish.
Did you know that you can monitor multiple locations in a home with a
*single* humidity sensor. And also detect smoke. And monitor volatile organic compounds such as gasoline, and natural gas. And ....ROTFL "Overkill" for what? The fish are already dead when you choose the Ocelot and try to kludge a solution for its shortcomings for this task.
( "When all you have is a hammer, everything looks like a nail." )
Yes, you need to be able "to make sense of the data". And once one moves beyond using the data to define a threshold for action in real time (Event-based trigger in ladder logic ala Ocelot and other current HA controllers), this requires being able to store the data which the Ocelot and SECU16 are next to useless for -- current efforts for a fix notwithstanding.
... Marc Marc_F_Hult
No. Humidity has units of Mass/Volume, often expressed as the ratio (in percent) of two humidity values (= "relative humidity").
One can estimate/measure humidity with the wet-bulb/dry-bulb method, but modern humidity sensors make this _much_ easier.
Most every formula is trivial ;-) What isn't trivial is making a compact, reliable device with the method you suggest for less than the price of a humidity sensor ($15-$20 ). They were invented and are purchased for a reason.
(Okay. I put "two temp sensors and a piece of cotton and some water" in each room of my house. Now what ? ;-)
... Marc Marc_F_Hult
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