Re: Trying to work with a CM11A under Linux

That's the best you can rhyme? Figures.

Unlike you two, I don't get my money from a welfare check. I have plenty of quarters and don't need the permission of net-dinks.

It would be helpful to know the noise spectrum of this power supply. As for the switch, heat from the triac might cause a change in circuit response.

Ooh! ooh! ooh! Pick me! Pick me!

I'll do it for a small fixed fee, a percentage of sales, and a percentage of profits (all negotiable).

And expenses, of course...

I think I'll need a new laptop to pursue this properly...

And a B-size printer...

Plus I don't know that much about ethernet interface, so I may need to take a couple of courses...

By "illegally" do you mean without a license, or intruding into forbidden bands?

Don't the airwaves belong to the people? Shouldn't the people be allowed to make any use they want of the airwaves, as long as they don't interfere with properly licensed/permitted signals, or cause a hazard to others?

The feds can be so picky. I am aware of a local ham who altered his portable to be able to listen to police bands. While mountain-biking with friends, one fellow got badly hurt. He called for help on the Sheriff's frequency, and the victim was saved. A few days later, the FCC paid him a visit and confiscated the device.

While "noise" frequently gets falsely blamed when the real culprit is a signal sucker, this _may_ truly be a case of noise. As I noted, a noise spectrum would be helpful in understanding what's happening here 'cause "what it is ain't exactly clear".

Yes.

Change the word "airwaves" to "air" or "water" or any other public resource. All have regulations because, in general, your actions in them can affect people quite a ways away without your knowledge. Just as fertilizer runoff from a field can pollute the wells of people far away, transmitting even small amounts of power can prevent reception of ("pollute") someone else's signal far away. Hence, regulation is a reasonable thing.

In the U.S., you can legally receive whatever you want... other than the old AMPS cell phone bands, and in my opinion the feds making that illegal was a mistake that, if anything, only delayed the introduction of reasonably secure cell phone technology.

Ah, well TRANSMITTING on the police bands is another issue. That certainly is illegal (for your friend). But note that the FCC confiscated the device specifically because it was modified and therefore no longer type accepted... if you friend had purchased, say, a police radio from eBay and had used it, technically I believe he would have been OK! (Since, in general, during an emergency you're allowed to use whatever frequencies and equipment you want to obtain help, but if the cops discover anything illegal after all the dust has settled, they can still pursue it. Say your friend had smashed the window of a car to grab a cell phone to call 911... technically I think he could then still be prosecuted for vandalism, although the cops might be a little more understanding because it was a spur of the moment decision, whereas modifying a radio to transmit on the police bands is highly premeditated!)

Keep in mind that while you can find stories where doing something like your friend did ended up saving someone's life, someone else could find a story where some moron transmitting on the police bands to report someone's house being robbed prevented a cop from calling in that he'd been shot and was lying there dying.

You have to put everything in perspective. Would I be willing to risk going to jail if I thought smashing a car window to call 911 in a true emergency would help? Absolutely. There's the old story about Thomas Edison smashing a the front display case window of a store to steal a large mirror so that a surgeon would have enough reflected candlelight to be able to perform surgery to save his mother. You have to decide for yourself when the overall good outweighs the bad if you choose to commit a crime...

---Joel Kolstad

[snip]

As they should have. He was too damned stupid to hide his "device" ?:-)

...Jim Thompson

Shut up! Do you want 'ass-barphed' to start writing another one of his patented, "John, the Rhyming Retard" poems about it?

Roses are red violets are blue my name is John and I'm stupid!

signed, the Stylish Tusker

BTW, who put a quarter in your slot?

I see how sharp you are trimming quotes to suit your purposes. If your intention was to out-lame John, you win the prize.

I have to disagree.

Signal suckers (attenuators) are usually passive circuits that always do the same thing. The only dynamic element in the mix is whether they are switched on or not. Some appliances have ~0.1µF capacitors across the mains at all times while others have their mains switch between the capacitor and the line. 0.1µF acts as a near dead-short to 120kHz - it's the value recommended for passive phase coupling. It's also a value frequently recommended for decoupling DC power supplies.

In the US, the FCC limits the amount of "conducted" noise on the mains in the AM radio band (approx. 450-1700kHz). The design engineers may also wish to prevent any RF frequency noise from entering their device from the mains. It's not surprising that they would choose a capacitor that happens to be X-10 unfriendly.

I'm not an expert on the line filters used with PC power supplies but the author of this page (

) appears to have some expertise. If his "typical" line filter (about 40% down the page) is truly typical they also use 0.1µF across the mains.

Switchmode power supplies should also have a more or less constant effect, again depending on whether they are switched on or off. If they have inadequate filtering, the frequency used internally (this frequency varies from manufacturer to manufacturer) will be seen as 'noise' on the mains which, depending on the frequency, may or may not pose problems for X-10. If they are adequately filtered, the filtering may or may not attenuate X-10 signals, depending on capacitor values. Noisy CFLs would seem to fall in the inadequately filtered class.

It might also be possible that two or more switchmode power supplies having frequencies which are individually X10-benign create a beat frequency that will create problems for X-10. This is the only scenario that I can envision with a dynamic element (both must be on to create a problem) but there may be others.

There are other factors that may contribute. For example, it may require two or more signal suckers to be active before problems appear.

It's difficult to envision and difficult to trobleshoot without a signal strength meter. True noise problems may require an oscilloscope and/or a spectrum analyzer. Since most of us have none of the above, we speculate and curse the undarkness in the middle of the night. ;)

You are badly misinformed.

It is even legal for me to require that you, for example, be of prime

36-DD quality ;-)

...Jim Thompson

I've measured a lot of PC power supplies with my Kill-o-watt meter (another toy you (Dave) wrote about and I subsequently bought!). I'd doubt that many PC's out there draw more than 5A and you usually don't plug the monitor into the filter so you'd be concerned with just the system unit's draw. I think my fastest machine, a 2800 Athalon, 2GB RAM and with four drives active simultaneously (RAID 1 + 0) while processing AVI's didn't draw more than

300W. IIRC, it was 273W. There are exotic PIC/ISA boards and USB devices that could really run up that number, so it's obviously best to measure.

In any event, I've been protecting my X-tenuating PC's with the 5A ACT and Leviton filters for a while now with no ill effects. In fact, some of them are filtering signal sucking UPSs as well as PCs and other small, problem loads like switching power supplies. The Kill-o-watt at least made me comfortable in sizing the correct UPS and filter for the machine. Slower machines, like PIII's and K7s run in the 135-150 watt range, at least according to the Kill-o-watt.

I hope I've factored enough overhead for inrush currents, which I assume the Kill-o-watt may have trouble reading accurately because the surges are so brief.

-- Bobby G

You can be sued because someone thinks you're ugly... doesn't mean they'll win!

Wow, you really aren't the sharpest tool in the shed, are you? That 'poetry' was an example of just how incredibly bad ass-barphed's poetry is, not my own! Hello --- it's supposed to be bad! My god, how do you function? Sorry Kieth, I just cannot buy into this fallacy that you are some kind of electronics professional, more likely you are a victim of lunatic asylum budget-cutbacks --- they thought you'd be ok as long as you took your medication, and kicked you out to save money.

Only those with previous work experience at Hooters ;-)

...Jim Thompson

It was an illegal device, is the point --- dummy.