Forums

computer-driven fans II

Started by Ron Ford July 25, 2008

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
> 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?
Jeepers Mr Peabody, there's a whole bunch of interface circuitry information and motor specifics missing! Without that information, I don't think there's any motor that can be driven directly by two microcontroller wires. JJS
On Fri, 25 Jul 2008 08:29:42 -0700, John Speth posted:

>> 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? > > Jeepers Mr Peabody, there's a whole bunch of interface circuitry information > and motor specifics missing!
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.
> > Without that information, I don't think there's any motor that can be driven > directly by two microcontroller wires.
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
Ron Ford wrote:
>
... snip ...
> > To repeat, I have a single fan to be driven by a microcontroller, > what wiring must exist?
The interface is extremely costly and complicated. One relay. -- [mail]: Chuck F (cbfalconer at maineline dot net) [page]: <http://cbfalconer.home.att.net> Try the download section.
On Fri, 25 Jul 2008 19:40:53 -0400, CBFalconer posted:

> Ron Ford wrote: >> > ... snip ... >> >> To repeat, I have a single fan to be driven by a microcontroller, >> what wiring must exist? > > The interface is extremely costly and complicated. One relay.
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
Ron Ford <ron@nowhere.net> writes:
> On Fri, 25 Jul 2008 19:40:53 -0400, CBFalconer posted: > > Ron Ford wrote: > >> > > ... snip ... > >> > >> To repeat, I have a single fan to be driven by a microcontroller, > >> what wiring must exist? > > > > The interface is extremely costly and complicated. One relay. > > 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)?
Correct. Whatever you do, don't switch the neutral line. That would be a violation of the electrical code.
On Sat, 26 Jul 2008 07:32:19 PST, Everett M. Greene posted:

> Ron Ford <ron@nowhere.net> writes: >> On Fri, 25 Jul 2008 19:40:53 -0400, CBFalconer posted: >>> Ron Ford wrote: >>>> >>> ... snip ... >>>> >>>> To repeat, I have a single fan to be driven by a microcontroller, >>>> what wiring must exist? >>> >>> The interface is extremely costly and complicated. One relay. >> >> 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)? > > Correct. Whatever you do, don't switch the neutral line. > That would be a violation of the electrical code.
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
Ron Ford wrote:

> 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.
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:

> Ron Ford wrote: > >> 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. > > 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.
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?
> > 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.
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
Ron Ford wrote:

> 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?
Yes. You can use whatever you have, e.g. something like this one: http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=CKN1025-ND
> 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.
Yes, they are inexpensive: http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?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: http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?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