I'm trying to build a PIC based X10 transmitter, at this point basically
an IR make/break based "toggler" for a light. I know that there are
modules that will do the AC interfacing for you, and all you do is send
serial data, but I'd like to build this.
It's maddeningly impossible to find a schematic, and from what I
understand, you use a transformer tuned with a proper cap that rejects
60 Hz on the AC end, and connect your 120 KHz oscillator to one end of
the other side of the transformer.
Does anybody know of a datasheet, etc., that provides a coherent
explanation of interfacing low-voltage DC to the power line? Something
X10 specific would be icing on the cake.
Also, what would be the best option to power the IR LED/receiver and PIC
*without* using a transformer from AC?
As David pointed out, the article describes a transformerless interface
between your PIC and the mains.
Also, for any X10 related reference a visit to http://www.geocities.com/ido_bartana/ would be most informative. Here, you
would find the schematic for the PL513, the original X10 transmitter
interface. You will notice it is fairly easy to duplicate this circuit,
although procuring the 120khz transformer might be a problem, especially
since it uses a 3 winding design.
Nuts n Volts also carried a project some years back that was essentially a
security device with X10 transmission capability. This design used a 2
winding transformer, and might give you some idea of how to use a close
substitute.
Ishaan Dalal wrote:
> Does anybody know of a datasheet, etc., that provides a coherent
> explanation of interfacing low-voltage DC to the power line? Something
> X10 specific would be icing on the cake.
>
> Also, what would be the best option to power the IR LED/receiver and
> PIC
> *without* using a transformer from AC?
I don't know much about X10, but I assume it uses a carrier that has a much
higher frequency than the 60Hz power frequency. If so, it should be easy to
capacitively couple the carrier signal into the AC line.
Many years ago in college I built an AM transmitter that injected its signal
onto the AC line instead of using an antenna. Separating the 1MHz carrier
from the 60Hz power voltage was mostly done with a 200V cap. Due to the
large ratio between 1MHz and 60Hz, separating the two was trivial.
By the way, injecting about 3W of AM into the AC line works very well to
make a radio station within a building, in this case a college dorm with
about 200 students living in it. The transmission could be picked up with a
portable radio in a courtyard about 20m from the nearest part of the
building. (We also discovered that interesting things happen to the city
water supply when everyone in the dorm flushes their toilet at the same
time. Radio is a great way to coordinate mischief.)
*****************************************************************
Embed Inc, embedded system specialists in Littleton Massachusetts
(978) 742-9014, http://www.embedinc.com
> By the way, injecting about 3W of AM into the AC line works very well to
> make a radio station within a building, in this case a college dorm with
> about 200 students living in it.
Hi Olin,
Competing with WRPI on campus, eh?
91.5 FM, WRPI Troy
(WRPI opened up my mind to some amazing and fascinating music)
Ken Pergola wrote:
> Competing with WRPI on campus, eh?
>
> 91.5 FM, WRPI Troy
>
> (WRPI opened up my mind to some amazing and fascinating music)
Our 3-5 watts wasn't much of a competition to WRPI's 5KW, although I know
that the signal hopped at least one power transformer and made it to
buildings up to 1/2 mile away. We did have a high percentage of people
listening in our little area as the toilet flushing incident proved ;-)
Surprsingly we didn't get into real trouble about that. I think the city
officials never found out what really happened, and the administration
didn't know what to charge us with. However, it was made very clear that if
we ever did it again they'd find something.
*****************************************************************
Embed Inc, embedded system specialists in Littleton Massachusetts
(978) 742-9014, http://www.embedinc.com
Ishaan Dalal wrote:
<...>
> It's maddeningly impossible to find a schematic, and from what I
> understand, you use a transformer tuned with a proper cap that rejects
> 60 Hz on the AC end, and connect your 120 KHz oscillator to one end of
> the other side of the transformer.
>
> Does anybody know of a datasheet, etc., that provides a coherent
> explanation of interfacing low-voltage DC to the power line? Something
> X10 specific would be icing on the cake.
Hi Ishaan,
Look on page 10 of this document for the PL512/TW523 schematics.
ftp://ftp.x10.com/pub/manuals/technicalnote.pdf
.Surprsingly we didn't get into real trouble about that. I think
>the city officials never found out what really happened, and the
>administration didn't know what to charge us with. However, it
>was made very clear that if we ever did it again they'd find something.
So what did happen - did you manage to empty the local reservoir or
something?
Alan B. Pearce wrote:
> So what did happen - did you manage to empty the local reservoir or
> something?
Not quite that drastic. The immediate effect was that those people taking
showers on the top two floors completely lost water for a few minutes.
There weren't too many of those because most were listening to the radio and
were flushing their toilets at the time. For the next half hour or so, all
the water came out brown. This was because the crud that had accumulated on
the inside of the water pipes had been shaken loose. It was mostly rust,
but some people went around screaming that all the toilet flushing had made
the sewage back up into the water. This was total nonsense of course, but
even at RPI you get an occasional management or hockey major.
Apparently it also had quite an effect on the Troy New York water system,
particularly in areas uphill of the dorm. There were some irate letters to
the editor of the local paper complaining about how there was no water at
all for half an hour on a normal day. The officials responding clearly
didn't know what had happened, and I don't think they ever found out. Both
the students and the school administration had their own reasons not to tell
the local officials about the incident.
*****************************************************************
Embed Inc, embedded system specialists in Littleton Massachusetts
(978) 742-9014, http://www.embedinc.com
>> So what did happen - did you manage to empty the local reservoir or
>> something?
>
>Not quite that drastic. The immediate effect was that those people taking
>showers on the top two floors completely lost water for a few minutes.
...
mitvma.mit.edu with SET PICList DIGEST in the body
