Re: Trying to work with a CM11A under Linux

Yes: MAINS>--+-----+-------------/ /-----+-----+------------------ | | | | | [C] | [C] | | | | | +--+--+ | +--+--+ +--| TX | +--| RX |--[LOAD]--+ | | | | | +--| | +--| |----------+ | +-----+ | +-----+ | | | | MAINS>--+------------------/ /------+------------------------

Looking at the caps connected to the mains, if inside the TX box we have something like this,:

MAINS>----+----------+ | | +--+--+ [C1] |TONE | | |BURST+-------+ | GEN | | +--+--+ [R1] | | MAINS>----+----------+

what we'll want to do is keep the 170V peak AC from damaging the tone burst generator, while at the same time allowing the generator to couple bursts of a high frequency tone to the mains. Just for grins, let's say that we'd like to keep the 60Hz down to about +/- a volt at the R1C1 junction, and we'd like R1 to be about 100 ohms. That means that we'll have to limit the 60Hz current through R1 to

E 1V I = --- = ------ = 0.01A R 100R

With 170V on the mains, that means that the impedance of R1C1 has to look like:

Now, since

Z = sqrt (R² + Xc²)

and we need to find the value of C1, we can rearrange to get the reactance of C1:

Xc = sqrt (Z² - R²) = sqrt (17000² - 100²) ~ 17000R

And the capacitance will be:

So now we have this:

MAINS>----+----------+ | | +--+--+ [0.15µF] |TONE | | |BURST+-------+ | GEN | | +--+--+ [100R] | | MAINS>----+----------+ and we want to place a signal on the mains. First we'll choose a nice high frequency (say 100kHz) so that the reactance of C1 will be nice and low to it, allowing it to pass through and onto the mains without attenuating it too much.

At 100kHz the reactance of 0.15µF will be

So that looks pretty good, and the last thing that needs to be done is to decide on the output amplitude of the tone burst generator.

If we say that our receiver has a sensitivity threshold of 100mV at

MAINS>----+----------+-------+ | | | +--+--+ [10R] | |TONE | | | |BURST+-------+ [1.44R] | GEN | | | +--+--+ [100R] | | | | MAINS>----+----------+-------+

Which is essentially this:

In order to have E2 be 0.1V, we'll need E1 to be

(R1 + R2) E1 = E2 ----------- = 0.794V R2

and the generator will have to pump current into the impedance formed by everything across the mains, which reduces to:

and, finally, to:

| [10.26R] |

which is close enough to 10 ohms for our purpose, which is to determine how much current the tone burst generator has to supply into

E 0.79V I = --- = ------- = 0.079A ~ 80mA R 10R

it'll be eminently doable, and as a matter of fact, upping it to 1V would get us better receiver operation and only require 100 mA out of the tone burst generator.

It would be interesting to try the 75 to 300 ohm TV baluns for audio. They are very very cheap...

It looks like A-bus requires power so I'd bet they are differential opamps.

Can you do this without a transformer? And if not, can you use a cheap off the shelf or surplus xfmr?

I played with one of these, and one pair is power, two pair are signals. The signal line is unbalanced.

-John O

It would not be hard to do, using standard discreet and analog modules to control various pieces of equipment, but since everything would be hardwired, it would be a pain. Not only would you have the wires for actuating a device, but then you should have wires for feedback. Then beyond simple discreet/analog control you might have devices that still require IR, Serial, or some other protocol.

You could use a PLC for simple stuff, like automating an Irrigation system, or turning on outdoor scene lighting, but I wouldn't rely on it as a whole house solution.

Have you considered some of the newer I/P enabled devices and using a LAN instead? Take a look at some of Global Cache's stuff. Also look at CQC as a net aware backbone for controlling. Heck, tcompanies are now coming out with Ethernet thermostats and other simple devices....Coffee pots will soon be next ;)

"All over the net?" Both yahoo & google searches for "wireless PC speakers" turned up dozens of hits. Need a new search engine?

From:hutchy snipped-for-privacy@yahoo.co.uk

Pest Patrol is also very good. You are right though, it seems that no one program can find every one. And if they do find one it may take another program to remove it or you have to do a complex manual removal. I got hit with Mdaddle and had to follow a 3 page procedure to get rid of it.

From:John O johno@#no^spam&heathkit.com

I think it's very unlikely that they would function well at audio frequencies. Not enough iron, and nowhere near enough turns.

Isaac

Thanks, I saw that, but what the heck does it mean? With the RJ-45 description is so far off the mark from how it would be described today, I'm not trusting, or understanding, the -41 description. RJ-45S? what is that?

My RJ-41 search results seem to point at low-speed telcom, older stuff, but how does it compare? Argh... :-) For instance, can a RJ-41 be Cat-5 certified? Cat-6?

A lot of sites seem to get these all mixed up, and I just can't stand the ambiguity. It's killing me. LOL

-John O

Take a visit to my site and see what I have done. Maybe find some ideas for your install. You can control the lights, fans, and cameras. I do have voice control for just about everything but if you think you will have 100% accuracy, you are wrong. It will be much closer to 80% with mikes. Too much interferrence from radios, music, other people talking. You will get better accuracy if you use wireless phones to make the commands more easily recognized.

I have Crown PZM-11A mikes in every room feeding a Shure mixer then into the computer sound card.

Don

I would suggest using RG6-Quad Shield for the video. I have all my cameras using it. Better shielding than with RG59. Most cameras I have found are

Don

Well I went to your site and registered but was unable to find any way to leave a message or post.

Don

Thanks for your reply BruceR Yes, I saw the links too. Unfortunately when you enter the link what you actually find are wireless hi-fi speakers or portable CD speakers - but I've yet to come across PC speakers. If you can suggest a model, I'd be grateful.

Cheers

hello robert.

the idea behind is to do as much as posible with low voltage. all the high voltage actors are controlled with relais.

i can get an easy 800 with 24 input and 16 outputs for 400 and serial communication cable for 400 ?.

all that nice i/p enabled stuff is so expensive...

volkmar

Yes, it is. We've been using RG-59 in the security industry for this purpose for several decades and it still works perfectly. RG6/QS is needed for high bandwidth applications like satellite. It adds nothing to the quality of CCTV camera systems. It is more expensive and more of a pain to use than RG-59.

True, but RG-59 without baluns is slightly better since it requires nothing but a connector at each end.

Yup. If you've only got CAT5 cable and it's inconvenient to run coax, use the baluns.

I'd agree that that's the best cable but isn't it overkill for a local camera? A good quality (i.e. Belden) RG-59 will provide better flexibility and virtually perfect picture quality. The thicker center conductor of the RG6 is great for broadband but doesn't really do anything for a baseband signal. In fact, even Cat 5 with baluns will provide a crystal clear picture.

From:Don snipped-for-privacy@k9soa.net