Remote temp sensing help??

This is probably overkill for your application, but I sell a kit of my own design that can do that...

It's really intended to be used over amateur radio, but if you don't have a license you could probably use it with a radio on one of the nonlicensed bands. MURS, maybe - I'm pretty sure telemetry is forbidden on FRS and GMRS.

I've got a number of users using these for temperature and voltage monitoring on remote mountaintop repeater sites. The cool part is that if you do have a ham license (easy enough to get), you can use an existing nationwide APRS network on 144.39 MHz that'll get your data onto the web. And because I've got so many people using these things for enviromental monitoring (I originally designed them for GPS-based vehicle tracking) I'm working on developing an email notification system, so you could be notified when the temperature crosses a defined threshold. That's assuming you're on the APRS network - standalone, you'd have to run a receiving station yourself.

Yeah, at 800 feet you're probably better off using off-the-shelf home automation stuff. But for ranges of many miles, this is a pretty slick (and cheap) solution.

Scott

--
Instead of having a continuous readout of temperature, probably the
cheapest way to go about it would be to have the sensors send you a
signal if the temperature at the sensor sites went below a certain
preset limit.  Something like, say, if you had a panel in your house
with four red and four green LEDs on it (one red and green pair for
each sensor) and the LEDs would stay green as long as the temp at the
sensor never went below, say, a few degrees above freezing.  If you're
interested, I'll work up something and post the schematic so you can
build it or have someone build it for you.  If you'd like to buy it
already built, email me with what "CHEAP" is and I'll see if I can do
it for that. :-)

I think I would look into the X10 wireless controls that use the 110 line as a signal path. There may be a thermostat type (alarms on low temperature) or sends actual temperature available.

If you can't find one a set that transmits temperature and alarms on received temperature, you can always get the simple switch kind (used as securuty sensors) and connect an ordiinary thermostat to it that opens or closes its contact it the warning temperature.

The fancy ones will call you at work.

--
John Popelish

Thanks guys,

I am keeping the temp around the 50 deg F mark using lots of insulation and a 7-1/2 W light bulb in the pump heads and small oil filled heaters with thermostats set at 1-1/2 (1-10 scale) in the insulated pump rooms. Not a cheap approach for the pump rooms but can't figure out what else to do as there's pressure tank and pipes and filters and softener and...

I have already had one scare on the day after Christmas morning just past. I awoke to no water. Fortunately the bulb in the wellhead must have died about an hour before I got up. The pipes had frozen (12 deg F outside) and as the pump pushed it would jam a slug of ice in the pipe, so no water. I stuck a fan heater in there for 3 hours and it finally melted it and all still OK.

John Popefish, the problem with the X10 stuff apart from it being crap (I have a bunch to sell if anyone is interested) I have two electric meters. Power company's idea!! One for the distant pump setup and another for the house and closer one. I don't think the X10 would span the grid, would it?

John Fields, your solution sounds fine to me. I can toss a solder iron around and can build from your schematic. I would very much appreciate that. I am happy with red/green LED's. In fact I'll probably add a piezo with the red LED. Someone might need to get down there in the middle of the night. Bbbrbrrrrrrrr.

Thel lowest I have seen the wellhead is 38 deg F, so I'd want it to trigger the red LED at 40. That way if it does hit 38, I can scoot down and make sure the bulb is still OK.

How involved would be setting up the transmitter and receiver frequencies after building? I have a a'scope but no signal generator. Could I buy a Tx/Rx set and just add your stuff? Say Vellerman/Ramsey or something? As to "cheap" probably $100 or less. Not wishing to whine, but single mom, couple of kids, so a walk around looking at harbor freight temp meters needs a lot of justifying to spend more than that.

Scott your solution does seem a little more than I have in mind, but thanks for the suggestion.

The distance one isn't actually used anymore, (long story) but because it is still a fully functional system, I don't want to just let it kill itself in the cold. Just don't seem right to let it die.

Thanks again for the quick reply.

--
Kind regards,
  Jenny and her tribe of survivors.

Good with kids, can handle a soldering iron, hangs out at harbor freight... sounds like my kind of woman. =] (Single parent myself, I know what it's like...)

I don't think you specified in the original post if this needed to be a wireless solution or not. If you don't mind running wires, you might be able to get away with a Dallas 1-wire bus. 800 feet is a lot of wire (and possibly a lot of trenching) though - but the sensors are cheap, and you only need two conductors.

Most of the wireless stuff I deal with is either short range (e.g., ZigBee, keychain remotes) or long range (many miles), not much in between. FCC rules aside, if I was doing this I'd probably hook a couple of my kits up to cheap Walmart FRS radios, with a third back at the house connected to a soundcard on a PC running a software modem program. The temperature sensors are built in, so no extra hardware there. Definitely helps to have a spare PC and soundcard available, though. There's hardware that'll do the decoding without a PC, but that'd probably go over your $100 budget.

Ceramic space heaters are pretty cheap. How about putting one of those in each enclosure, with a thermostat set a few degrees below the normal heater's range? Then just inspect the sites from time to time to make sure the primary heater hasn't failed.

Scott

LOL

Thanks Scott. Been at this alone stuff so long I am now convinced a woman needs a man like a fish needs a bicycle. I know, it's a copied joke but my life has been a LOT less complicated over the past 5 years.

You are correct, forgive me, I scooted right past that one as I was thinking "radio" but just forgot to let you guys in on the secret too. Oooops. The frailties of mere humans of the weaker sex, I guess.

I have an overhead link back to the house via wires from all four, so I guess I could use wire. I am not sure why the link on the distant wellhead is there, but it is. I have just recently bought this place and still learning, but I could run wires overhead.

--
Kind regards,
  Jenny and her tribe of survivors.

If both meters run off the same pole (or buried) distribution transformer, they should.

--
John Popelish

OK, thanks guys, too many to answer individually so will try and remember all suggestions.

I think so, there is a can at the top of the main pole into the property so maybe the X10 is worth a try. My bitch with X10 was when using them to control lights in the house. The controller would occasionally scramble it's brains and I have to fire up the software and reset all the start/stop times. A real pain in the arse. The other thing was that the wall outlets use relays and when they switch on/off there is a hellasious clunk. I had assumed they would use solid sate relays. DOH! Just as you are dozing off to sleep the X10 turns off the lights somewhere, bingo wide awake again. POS!

OK, back to the issue. I think I see a woman walking the rounds looking at the temp meters. Although someone suggested a light I can see from the house. That might be a good alternative, I can't see one wellhead but I can run a 30' wire to the pump shed for it's light. As to sleeping with a window open in Winter, who ever suggested that obviously lives in Florida. LOL. With 12 deg nights, it's hard enough to stay warm as it is.

I had thought of the R/C thing and actually have a 2-channel here somewhere. However given the obvious complexities involved with most of the suggestions, I think I will thank you all very much for your help and head out the door to read my meters.

It seemed like a good idea at the time, but it is just getting too complicated compared to a 5 minute walk. The only thing I might do is rig some sort of warning siren and screw the neighbors. Just kidding they wouldn't hear it.

Thank you very much to all of you for trying to help.

--
Kind regards,
  Jenny and her tribe of survivors.

This has all been very interesting for me to read. Jenny, thanks!

My own situation is quite similar to Jenny's. I also have a pumphouse, for example, that is also on a separate power meter *and* a separate transformer system, as well. My own pumphouse is approximately 1200 feet away, as well as downhill from the main house by about 150 feet (so I have about 75 PSI difference between the pumphouse pressure and house pressure.)

There is wiring between them, for pump control relative to the storage tank pressure at the house, but it's a buried line (sadly, it appears that at least some of it is buried without any conduit, as well -- I've seen it near the house.) Trenching for new wiring would be ... very expensive. And there is no existing set of poles for mounting above ground wiring.

There *might* be a line-of-sight possibility between the house and the pumphouse, but there are many fir trees as well as maple, birch, and ash in between, so providing a clear path in winter and summer might be tricky.

I do *not* have a HAM license.

Data rates could be very low and high error rates could be tolerated, as long as command/status updates of once per 10 minutes or so could occur in each direction.

Bidirectional laser communication would be an idea, assuming I can find a suitable optical path (maybe) -- I'd consider using a 4X gunscope for the receiving end of each side, I suppose, with a detector placed appropriately. And an adequately powerful and appropriately aimed laser emitter. But it would still need to operate in broad daylight or even in the not-infrequent heavy snow and ice environment in the winter. Optical filtering as well as tight control of modulation with a narrow band receiver as used in street light controls might be appropriate. But it starts getting pretty tough for something reliable, I think.

An RF arrangement would be simpler in ways, but it would require a sufficient transmitter/receiver combination. And for that distance, I imagine that operating on a single wavelength would probably violate FCC regs. one of the several (two, I think) non-military spread spectrum techniques might be an option, but I'm not sure. It's possible that accepting very high bit error rates through the use of encoding and decoding protocols may permit legal use of a single prime frequency.

Sounds like the FRS two-way radio idea is worth considering for this, though. I've already checked out a pair and they work excellently for voice over this distance. I'll start looking into that further, now. If there are some other interesting thoughts about it... I'd be interested in those, too.

Jon

I've had X10 on my list of Things To Try for about 10 years, so I still have no practical know how. But, like JP, I'd have thought that a sound approach too for this spec. Potentially compelling advantage that all the mains wiring is already in place. Has your experience with it really been that bad?

But, excluding that, for reliability and cheapness I think I'd favour the hard-wired approach. The wire itself will be the most expensive outlay. Despite needing to carry only a low current signal, the cable diameter will probably need to be fairly substantial for robustness. (My garden lamp relay box is probably only 100' from the shed-based control circuit, running along a fence behind flower borders, but the original thin wire I used proved inadequate against careless hedge cutting and rose pruning.) The cable would link JF's temperature detecting circuit to your house LEDs and piezo.

BTW, for further simplicity (and cost reduction), wouldn't it be possible to use just *one* sensor? If the general temperature is close to danger level, then I'd have thought all four sites would be close to their 'risk thresholds' ?

If the distance had been much less I'd have gone for adapting a wireless door-bell. I've used that successfully for several projects. But I suspect a radio-based approach for reliable 800' operation would be rather expensive.

I don't suppose you can *see* all 4 sites from the house? If so (and if other factors like neighbours don't rule it right out) I wonder if it might be possible to use a mains-operated lamp at each of the four sites. If necessary, with an additional appropriately-positioned mirror or two. And, again subject to the neighbour proviso (and your willingness to sleep with a window ajar in winter), maybe a loud but cheap piezo at each location, or shared if some of them are close?

Hmm ... on reflection, and thinking about safely routing all that wire, radio begins to look attractive . I think I'd look at a cheap R/C model kit (plane or helicopter, for the range). Adapting one for simple on/off switching could be fairly simple. Fun too.

--
Terry Pinnell
Hobbyist, West Sussex, UK

An issue of Circuit Cellar several years ago had an article on an X-10-based system for something similar to what you need. The author wanted to turn a fan ON/OFF in his kid's 2nd- or 3rd-story bedroom, depending on temperature. PIC-based trnasmitter queried upstairs receiver for temperature via X-10 (TW-523?). Receiver measured temp., sent back either a HIGH or LOW signal. Transmitter could then either ignore the situation altogether or send an ON or OFF command to the fan's X-10 appliance module.

I was on the verge of building the thing when my need evaporated. If you'd be interested, I'll look up the article.

By the way, I agree than some X-10 stuff is junk. But for the past 15+ years I've used the simple desktop manual X-10 controllers, the bedside table clock/controller, and lamp modules to great advantage. If I had to get out of my TV chair to make a light brighter or dimmer I wouldn't know how to act. And the last time I turned OFF the downstairs lights

*before* going upstairs to be was in the late 1980's.

Thanks Michael,

I think I will stick with the walk and the temp meters for the time being. It isn't as simple as I suspected or hoped it might be.

I agree on some of the X10 stuff, but it drove me nuts about every 3 weeks the lights would start coming on in the middle of the night or day, or stay on all the time.

I called them and they said spend more money on their filters. I figured I had thrown enough good money after bad so put up with resetting them for about 12 months then tore out all the outlets and went back $3 timers from walmart. Not quite as hitech but they work and still are 3 years later. The timers don't have that loud relay CLUNK either. KISS in place now, and I suspect that's the best idea for my wellheads and pump rooms too.

Thanks anyway

--
Kind regards,
  Jenny and her tribe of survivors.

Hi Jenny,

You didn't say as to what the overhead link wires do - AC power; DC power; telephone or intercom link; or other ?

Oz-Rod

--- You could make the thing wireless if you wanted to, but I seem to recall that you said in another post that you have wiring available to all four locations. Is that the AC mains wiring or do you have something like an extra pair of wires going to each location? If you do, that would make it far more robust, easier to set up, cheaper, etc.

Also, it would make it possible to power the temp sensors from the house unit and eliminate the four power supplies in the pump rooms.

What I'm thinking of is something like four little boxes (senders) with temp sensors and the necessary circuitry in them to trigger the receiver alarm, a 2-terminal terminal block to connect them to the wires going to the house, and a box (receiver) in the house with a green POWER LED, 4 red and 4 green LEDs to indicate OK temp and undertemp for each channel, a piezo sounder and a RESET pushbutton switch to reset the sounder, and an 8-terminal terminal block to connect the wires going to the senders.

The whole thing would be driven by a single (probably 12V) wall-wart with a regulated output which would plug into the receiver and run everything.

If you have that extra wiring, could you describe it? That is, its construction (lamp cord, twisted pair, twisted shielded pair, coax, ???) and the diameter of the conductors (or the AWG)?

Also, do you get much lightning where you are and are there any radio or TV stations close by?

-- John (a bicycle) Fields ;)

Hi Jenny,

Here in OZ back in July 2003 (would you believe it is now Jan 2005) - our local electronics magazine

- SILICON CHIP - featured an article on using an PICAXE chip for communications purposes AND even had a small section referring to 'wireless' linking using prebuilt hybrid 433MHZ UHF radio modules at each end - reasonably cheap & developed for licence-free radio links. Now with a simple directional RF antenna it is suggested that such links could reach up to a few kilometers.

If you think this type of circuit arrangement may be useful, you might want to look at getting a kit from one of our local suppliers -

- they can supply both the RF modules as well as the Picaxe chips - if you need any additional 'interface' circuitry then let me know and I'll see what I can draw up for you.

Oz-Rod

electronics magazine

purposes AND even

433MHZ UHF radio modules

with a simple

kilometers.

look at getting a kit

both the RF modules as

then let me know and

BTW: I forgot to mention that the PICAXE range of chips can do reasonably well at reading temperature from various sensors (part of the in-system program).

Oz-Rod

You must have missed her follow-up news: snipped-for-privacy@4ax.com in which she opted out of an electronics solution!

--
Terry Pinnell
Hobbyist, West Sussex, UK

--
Yup. Oh, well...

You should be using pipe heater tape and not a light bulb on that well head. What is the layout of those pump houses- can you daisy chain a path between them and back to the house? The simplest solution would be to buy a 1000' spool of 4-wire direct burial telephone cable off the surplus market for ~$50 - you can just string it out for now and wait until spring to bury it. If burial is not feasible, then a UV resistant type strung along a fence or whatever is another option. Then do a

4-20mA current loop transmission of the temperature.