Christmas Lights Problem

Pulled a dedicated 20A for the fish tank and chiller.

Don't know the brand, bought it at Paddock at least 5 years ago.

That suggestion did not clear the "management" review ;-)

...Jim Thompson

-- Service to my country? Been there, Done that, and I've got my DD214 to prove it. Member of DAV #85.

Michael A. Terrell Central Florida

I saw a similar item at the dollar store and grabbed a few. LED and battery with a couple of transistors.

On a sunny day (Thu, 21 Dec 2006 22:34:58 GMT) it happened Joerg wrote in :

GSM cellphones. They are the worst, give out 4W pulse, several bands in use. Everybody in the building has one. I could not use my old walkman in Amsteram in the tube, always somebody near on the cellphone, rrarrrarrrarrrarrrarrra rrarrrarrarrarrarra sort of sound (AM detection in input amp). I could hear they were being called before it rang :-) Mp3 player is OK though. You absolutely need to 100% screen and filter _all_ in and outputs, including supply lines, feed through caps, LC, ferrites, etc. There is CB (some use 1kW) at 27MHz, police around 100?, and celphones higher up. Then there is radiation from the DSL over copper, and from all unscreened ethernet cables. Plus the radio and TV of course.....

Yep, the AC detectors work great on loose strings, but fail on a pre-wired tree... with metal-core branches... and AC lines wound around them. It'll go off 6" from anywhere on the tree. :-) The binary method works much better.

Grab your voltmeter. Find the first and last light out in the string. Pull the bulb from one of them, clip one probe to the socket's lead, and start a binary search in the middle. If you get voltage across the leads, move 1/2 the distance to the first light; if not, move 1/2 the distance the other direction. On a 100-light string, you can find the first bad bulb in less than 8 steps; repeat to find the next one.

To clip the first probe, I use an empty bulb holder to press a length of wire-wrap wire against the right contact.

Cheers, Richard

One of my guys has an old (analog?) cell phone. He has to leave it somewhere else when he comes into my office, because my RatShack speakers make machine-gun noises if his phone gets near it.

This particular product needs picosecond in-out jitter, and the outputs have 600 ps (5 volt!) risetimes, so I can't filter anything. Next rev, maybe I'll put the critical oscillator under one of those little photoetched metal RF boxes and filter the hell out of its supplies.

Now that the FM is mostly gone, it looks like my uP clock is also wobbling the oscillator a little. If I have the guts to overclock a 16 MHz CPU (it's the 3.3 volt version of the MC68332) at 20 MHz, that will get synchronous and maybe go away.

John

LOL, microwave the tree! Seriously though, a CB radio would be a good source of RF for that, 4 watts into a coil on the end of a piece of coax cable would light the good bulbs nicely and be fairly easy to tweak so it only lights bulbs close to the coil.

The inductance of coiled filaments might screw that up too!

AFAIR the GSM phones work above 800MHz, depending on the band the provider uses. We are definitely not getting anything into the system abover 200MHz, it's like a tank up there.

In hospitals they are supposed to be turned off. Of course, many people don't do that but in this case the lab where the noise happens is far away from normal foot traffic. Only well trained employees and they don't carry phones or anything, it's a large sterile zone.

A simple tuner box should do, it's probably a lot cheaper. But tack two corners of the lid on with solder so it doesn't separate if the unit is banged around a bit.

Maybe 10MHz with a nicely controlled duty cycle?

On a sunny day (Sat, 23 Dec 2006 18:13:29 GMT) it happened Joerg wrote in :

Coverage and frequencies for .nl:

One standing next to 'equipment' with a cellphone in the pocket, it can be on vibration alert for example, receiving SMS or whatever, it will try to reply to polling from the base station, and increase power to full if need be (to get an ack). So 4W at say 1 meter distance, calculate how many dB attenuation your 'tank armor' needs, to have a signal inside the tank so low that it has no effect.

There are many other sources, in Amsterdam I could hear the electric tram driver coming through an audio mixer I desiged.. Filtering did help 100%. There exists baby monitoring sets that use the mains.... RF FM. Wireless phones, one guy got arrested because his wireless phone interfered with the F16s on the nearby base... Have fun:-)

Compulsive as ever, I tried overclocking the 16 MHz-spec'd CPU. It seems to crash my program when clocked at a bit over 45 MHz. So with a very minor board hack, it looks like I can safely clock the CPU at 20 MHz and have everything on the board be synchronous. We're already using an LTC dual switcher running at 2.5 MHz, sync'd to the system clock.

The worst part is that my program listing is full of comments about loop timings and subroutine execution speeds, and I'm doing a lot of software-timed stuff, and I'll have to edit all that. But the ratio will be exactly 16/20, so at least I don't have to measure anything again, just scale it.

LC oscillators are interesting as regards injection locking or, in my case, injection wobbling.

John

ROFL

Merry Christmas :-)

martin

Not a brand, it's in a must-see Christmas movie:

Ah, yes. Just like my suggestion that we really don't need to replace a broken hot water dispenser. Mankind don't need all them thar luxury thangs. Didn't fly with the missus. So it was back pain time again, crawling under the sink :-(

Almost as much fun as fixing a car radio.

John

Or a cutting torch.

Ah, yes, I remember being young and flexible enough to crawl under a dashboard without pain, with my butt up on the car seat ;-)

...Jim Thompson

I didn't work on it the last time. Some idiot did and he managed to tighten the U-bolt 1/2" into the pipes without breaking it. Even if they were brand new, they would have required the torch to separator. To add insult to injury, my goggles were damaged, and I couldn't get far enough under the truck to see what I was cutting. I managed to cut the outer pipe from the old muffler lengthwise and peel it off the pipe from the catalytic converter without damaging it.

Buy a Chrysler product next time, my history of six minivans from 1990 to present, never put a pipe or muffler on any of 'em. All stainless steel from the manifolds to the tailpipe tip. Don't know why all the carmakers don't follow suit. Merry Christmas to all, Tom

Buy? BUY? I didn't buy the truck, I rescued if from the car crusher. Its a 1987 Ford Ranger with a couple hundred thousand miles on it. I was given the truck, and the new radiator it needed, almost two years ago. I have tuned it up once, and replace the muffler, since then. My '79 Dodge pickup truck is sitting in the driveway, waiting for an engine transplant. I paid $500 for it, and drove it for eight years. Before that, I had a '79 Chevy Malibu Ex-Sherriff's cruiser that I paid $500 for, and drove 86,000 miles. I usually spend more on gasoline than I pay for transportation. :)