Don't Get Caught in the Web

Posted by bob on October 25, 2018


The World Wide Web is full of amazing, useful, and entertaining content.  Unfortunately, a lot of the information is wrong. By “a lot of the information” I really mean most of it.

One should always apply the CRAP test to information you find on the web.  Do some research and see if other people with some level of authority (expertise, experience, credentials, something) are expressing a similar opinion.  Does the information even make sense?  Can you work out for yourself reasons why the information is logical or why that source might be giving you bad information? Are they speaking from knowledge or ignorance?

I like to read photography forums to learn better ways to capture both stills and videos.  It can be frustrating to wade through some of the threads, which may be filled with incorrect or misleading statements.  I eventually realized that there were a few smart folks who backed up their assertions with sound research and references.  They show their work and therefore become far more authoritative.

A few months ago, I was searching on the web for information regarding some interface cables to a particular conference-call phone system.  I found several sources that suggested one of the cables should be a POE (Power-Over-Ethernet) connection. 

Nope, those contributors were wrong, but their confusion was aided by the fact that the manufacturer had used an 8 pin modular plug, very similar to a classic “RJ45” Ethernet connection.  The manufacturer had indeed taken the extra effort to use a keyed plastic connector, which would prevent inserting their special cable into POE equipment.  However, this method did nothing to prevent folks from inserting standard Ethernet or POE cables into their phone system.

I don’t fault the manufacturer for failing to prevent every conceivable wrong connection, but I do fault them for intentionally refusing to clearly document the voltages and signals present on their equipment.  I suspect that their after-sales marketing team enjoys the high markups they get for their cables and accessories and tells the engineering and support groups to refuse requests for what would otherwise be reasonable documentation.

The same company sells an adapter cable that connects from a Tip-Ring-Sleeve (TRS) 2.5mm phone-plug to two 3.5mm TRS plugs.  Some folks on the web decided that they could build their own, much cheaper.  They documented their efforts with basic pictorial diagrams that I immediately believed were just plain wrong.  Why did I think this? 

They showed a design that shorted together the LEFT and RIGHT channels of a stereo output to feed a monaural input.  Ouch!  Many amplifier designs in the real world do not include (or cannot include) series protection resistors of appropriate size.  Shorting two audio outputs together is questionable at best and could easily damage upstream equipment.  Damaging a mobile phone or laptop motherboard would be foolish if you were simply trying to save a few bucks and did not understand the limitations of the technology.

I had been watching eBay auctions for a used copy of the manufacturer’s version of that audio cable. A pre-owned cable finally popped up for a reasonable cost, so I went ahead and bought it.  As soon as the cable arrived in the mail, I spent a couple of minutes measuring resistances. 

Sure enough, the manufacturer’s authentic cable included series resistors for both channels of the input stereo summation and another resistor to protect the conference phone audio output.  The cable electrical design was excellent and the physical cable construction quality also was very good.  (Whether the manufacturer’s genuine cable represents a good value is not important to this discussion.)  My point here is that many people might break relatively expensive equipment by following bad advice from a random suggestion on the internet.

It is unfortunate, but true, that I have encountered dozens of internet postings claiming that certain devices did not work or could not work; but many of these comments betrayed a fundamental misunderstanding of the many wiring arrangements used with TRS and TRRS connectors. The connectors might look similar, but the wiring for different applications is different. I hope that statement does not surprise you.


About that spider photo…

During a trip to Taiwan last year, we took some time to visit a spot on the coast.  One person in our group noticed this spider and her web in an open space of a large sign.  “Go behind the web to give us some reference for the size,” said my colleague.  I did that and was shocked at how large the spider appeared up close.  It was not until later, when I was able to view the photo that I realized I had forgotten I was wearing a hat, with a long brim.  That hat brim was far closer to the web than I realized, and it was miraculous that I did not end up with a face full of web—and a face full of spider.

Please, be careful of what you find on the internet and in nature.  Don’t get caught in the web.

My thanks to Régis Lequeux for his excellent photograph.  Also, my thanks to Didier Roustide for his identification of the spider as Nephila pilipes pilipes; or giant golden orb weaver.