I intend to use WINAVR from Atmel to give instructions to a fan.
My computer is fifteen feet from the fan. The target device, a RISC-8 controller, is between.
If the fan is to be the one that I've salvaged for this purpose, it has two hot wires and would be governed by either being on or off.
Given that I have a hundred bucks to get necessary "software-hardware," what do I need to do *now* to get wires where they would need to be?
To repeat, I have a single fan to be driven by a microcontroller, what wiring must exist?
--
When a new source of taxation is found it never means, in practice, that
the old source is abandoned. It merely means that the politicians have two
ways of milking the taxpayer where they had one before. 8
H. L. Mencken
On Fri, 25 Jul 2008 08:29:42 -0700, John Speth posted:
I would think that a microcontroller could not supply the amperages that we're talking about. I would think the microcontroller would only complete a circuit that would have the regular house wiring as the source of power. I've never done this before, so I simply don't know what's involved.
I was thinking that having a black and a red wire as hot wires would be a good thing, so power could be supplied by the microcontroller completing a circuit on the black wire and the red wire could go to a regular switch.
I have no idea what to even google for to find out more. Who said "jeepers, mr. peabody," rocky the squirrel?
--
Unquestionably, there is progress. The average American now pays out twice
as much in taxes as he formerly got in wages. 1
H. L. Mencken
On Fri, 25 Jul 2008 19:40:53 -0400, CBFalconer posted:
Then a relay takes a signal from the microcontroller and completes a circuit that runs off the house or the opposite (cuts the juice to the hotwire)?
--
When a new source of taxation is found it never means, in practice, that
the old source is abandoned. It merely means that the politicians have two
ways of milking the taxpayer where they had one before. 8
H. L. Mencken
On Sat, 26 Jul 2008 07:32:19 PST, Everett M. Greene posted:
It's also a very unfriendly thing to do to remodelers like me. It's one reason a carry a non-contact voltage tester in my standard toolbox. Repairs here in the US southwest show the education level of the implementor: hardly existent.
The way I was thinking, there would be two ways to switch the state of the fan, since there are 2 hotwires on it:
1) a switch that works in the hallway like any other normal switches.
2) a circuit that is opened and closed by a microcontroller and relay.
The part (one of many) that I can't picture yet is how the homeowner can "overrule" the microchip and switch the state of the fan.
--
War will never cease until babies begin to come into the world with larger
cerebrums and smaller adrenal glands. 2
H. L. Mencken
I would add the switch (maybe 3-pole: automatic, on and off) to the microcontroller, which then can sample the switch state and control the fan.
Take care if your fan is powered by mains power when building the housing for the circuit and ask someone who knows how to make it safe. And for the low voltage side of the relais you'll need some more amplifier (maybe a FET), recovery diode etc.
--
Frank Buss, fb@frank-buss.de
http://www.frank-buss.de, http://www.it4-systems.de
On Sun, 27 Jul 2008 02:11:16 +0200, Frank Buss posted:
This sounds like a piece of hardware. Would it presumably be connected to the microcontroller by a wire appropriate for a 1.5-5 volt signal?
Even with this simple situation, at some point you need to provide a stimulus for the controller to react to, and that is, at a minumum, something that would be able to measure the temperature and able to send 8 bits of information.
I would need to measure temperature next to the woodburner and at the other end of the house, the part that is "downwind" of the fan. If they're inexpensive, I could have more.
I wouldn't know what to google for to inform what it is I'm looking for here.
--
When a new source of taxation is found it never means, in practice, that
the old source is abandoned. It merely means that the politicians have two
ways of milking the taxpayer where they had one before. 8
H. L. Mencken
Yes. You can use whatever you have, e.g. something like this one:
formatting link
?name=CKN1025-ND
Yes, they are inexpensive:
formatting link
?name=568-2051-1-ND
If you have long wires from the temperature sensor to the microcontroller, I would recommend a RS485 bus. Add a small microcontroller with UART support (about $1) and a RS485 driver, like this one:
formatting link
?name=497-2080-1-ND
at each temperature sensor. Then you can connect all temperature sensor boards in one line with one long 4-pole cable (2 for RS485, GND and supply voltage). Twisted cables for RS485 is a good idea. On each board you can add some jumpers to set a RS485 bus address.
--
Frank Buss, fb@frank-buss.de
http://www.frank-buss.de, http://www.it4-systems.de
On Sun, 27 Jul 2008 03:59:53 +0200, Frank Buss posted:
I'll assume that since no else objected amid a lot of opinions that this is a good way to go.
It really helped me to see the pictures that come with these listings. Temperature sensors look like cockroaches with eight legs. The first pin is on the left as you read the name left to right, and it is symmetric about the axis that would be the length.
Do these things need to be mounted on a board where they are to measure the temperature, else how do pins interact with wires?
--
Unquestionably, there is progress. The average American now pays out twice
as much in taxes as he formerly got in wages. 1
H. L. Mencken
There is (usually) no single best answer. The sensor noted above will offload a lot of the calculations at the cost of some complexity in its interface. Many other options, including (1) volts/degree sensors
(2) NTC thermistors
(3) thermocouples
(4) RTDs
(5) thermopiles
and I'm sure several more that just fell out of my head this morning.
One solution driver will be the expected temperature ranges next to the woodburner and also at the other end of the house. A single sensor or sensor family may not be the best in both situations.
Also pay attention to accuracy as well as precision. The SE95 "Ultra High Accuracy" sensor provides 13 bits of precision (0.03 C) but only
+/- 2 C of accuracy (depending on temperature range & supply voltage). That's probably a lot-to-lot max/min and individual chips can probably be calibrated more closely.
Yep. That's another solution driver. Other sensor types, e.g., thermistors, can be mounted remotely at the end of relatively long wire runs with a (also relatively) negligible effect on the result; 100K ohms for the thermistor, versus say AWG 24 hook-up wire at about 25 ohms per
FYI, those initial lines that say "Joe wrote:" are attribution lines. The attribution line is associated with quoted material lines with one less '>'. This both credits the original author, and uniquely identifies the individual sections. Don't delete them, unless you have deleted all material by that author.
Because you snipped attributions, I have no way of knowing who wrote the material with >>> or >> leading the sentences.
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[mail]: Chuck F (cbfalconer at maineline dot net)
[page]:
Try the download section.
Of course not. All you have to do is tell the cockroach where to sense the temperature. This requires a clear knowledge of cockroach language, together with clear enunciation. Then you can take proper advantage of the cockroaches extra-sensory perception.
--
[mail]: Chuck F (cbfalconer at maineline dot net)
[page]:
Try the download section.
Depending on your definition of "really matter" yes...no.
But I sure like to know who wrote what, it makes conversations much clearer. In this case I know Chuck wrote the text you replied to, but only because I just read it. If I had seen this message tomorrow, chances are that I had already forgotten that.
Do you remember each post you read on usenet and who wrote it? Or do you read back old messages to try to figure out who wrote what? Or do you just don't care who wrote what?
--
Stef (remove caps, dashes and .invalid from e-mail address to reply by mail)
Future looks spotty. You will spill soup in late evening.
(Actually, Chuck wrote, in response to a post where John had not provided attributions, just like he did when he then replied to Chuck)
Indeed.
Knowing who wrote what helps the reader decide how much to trust what's written - it's not just what you say, but what you've said in the past (and what others have said about you, and you about them yea back unto the N-th generation) that matters in a reputation-based system like Usenet. When you do not supply attributions for something you quote then instead of serving as backup or counterpoint to what you're saying, it's the equivalent of "I heard somewhere that ...".
On Mon, 28 Jul 2008 14:56:26 -0400, CBFalconer posted:
This sounds like you're having a little fun with my inexperience. Fair enough, I'm attempting to do something ambitious and am a certifiable neophyte.
The cockroaches here on the Rio Grand are commandos with *amazing* superhero abilities. There are so many out on the streets at night that one can sensibly talk about a cockroach pressure around here. They have a meeting with their buddies and then move out in pods. I think they're smarter than your average Texans.
--
Unquestionably, there is progress. The average American now pays out twice
as much in taxes as he formerly got in wages. 1
H. L. Mencken
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