Mike Johnson is the principal engineer for Mike Johnson Broadcast Technology in Portland, Ore. He read our column about the CATV F-to-RJ45 adapter and realized he had something to contribute to the discussion.
While Mike was helping build out the new facility for All Classical Portland in 2014, a coworker showed him an adapter he had discovered to make the connection between StudioHub and AES3 digital audio simple.
The solution is to use the three-pin XLR DMX lighting standard, which was later adapted to work over RJ45 cables. Like the CATV adapter we described, it uses the first pair in the Category cable. The adapters are available as short, three-pin XLR male or female plugs on one end to RJ45 jacks. The photo shown here is typical; you can find that connector at markertek.com, type DMX-5XF-CAT5 into the Search field.
The DMX standard started out with a five-pin XLR, but it didn’t need all five pins. Sweetwater has a discussion on understanding DMX.
These DMX adapters eliminate the need to use a dual XLR-to-RJ45 adapter dongle for AES3 digital, which results in an unnecessary, awkward right channel XLR connector (since the AES3 signal only travels on the left analog connector). The DMX adapters are short and can be plugged directly into the equipment, making for a neat, uncluttered conversion.
A little strip tease
San Diego’s Marc Mann says Frank Hertel’s choice of silicone-jacketed wire in his LED fixture dimmer project reminded him of an interesting experience.
First, Marc notes that to his knowledge, silicone-covered wire was reserved for premium test leads, as the flexibility of the jacket allows the probe clips to remain in position. The silicone formulation is also heat-resistant.
Raise your hand if you don’t have at least one pair of test leads with a soldering iron burn on the jacket! Marc chose the silicone-covered wire when he needed to make some six-foot leads for his power supply. He purchased some 16 and 18 AWG (American Wire Gauge) wire from Ali Express and eBay. Each length of cable was manufactured off-shore.
When he stripped the lead off the 18 Gauge wire, the wire pulled straight out of the jacket. Not just one strand, but all of the strands. No matter how cautious Marc was to strip just the jacket, the wire still pulled through — the silicone jacket was not bonded to the wire!
The wire was also mismarked. Although the jacket said 18 Gauge, it was actually closer to 20 AWG.
Marc then discovered that he did not have 100 percent copper wire, rather CCA or copper-clad aluminum.
From another website, Marc learned that the advantage to CCA wire is that it is lighter and more flexible. The cost of CCA versus oxygen-free copper wire is also much lower.
So Marc warns buyers to confirm the composition and specifications of the wire you are buying, especially from online sources. If your application is critical, such as in a high-power transmitter, the variations could make a difference.
Little light, big impact
Glynn Walden, too, dropped us a note about Frank Hertel’s LED dimmer circuit, and commented how far LEDs have come since his first experience.
Glynn was in his fourth year of engineering studies at Florida International University, when someone brought in a new diode that emitted a visible red glow when it was placed on a curve tracer! Glynn says this was around the time that the 555 Integrated Circuit (IC) was replacing all of the old mechanical timers.
He writes that he could never have dreamed that this little light-emitting chip would one day replace the incandescent bulbs in a console, let alone the headlights in your car or the light bulbs in your home. Or, for that matter, the beacons on a tower.
Agreed. We are fortunate to be living in such a time where the innovations and improvements just keep on coming.
Glynn is retired from CBS Radio as a senior VP of engineering, but he is probably best known as the father of the in-band, on-channel digital broadcast system now known as HD Radio.
Speaking of improvements, 3M’s Filtrete pleated air filters division offers an app that lets you set reminders for changing filters or ordering replacements. The app can also take into account air quality in your region so you’re changing filters based not only on time but on air quality.
In online reviews, users say the app saves them money because they don’t change filters too soon. Filtrete also has a filter model with a built-in sensor linked by Bluetooth to your phone, though according to some of the reviewers, the reliability of this new feature seems questionable.
In any case, if you’re looking for a quick reminder for filter replacement, this app may be for you. It’s available on at Apple Store or Google Play, or search “Filtrete Smart App.”
On a related note, I had my home air conditioning system serviced recently and I noticed the technician jotting something on his hand. I asked what it was and he told me it was to remember the thermostat set point when he was resetting the thermostat after his testing.
He told me that he was using the “original palm pilot.”
John Bisset, CPBE, has spent over 50 years in broadcasting and is in his 31st year writing Workbench. He handles western U.S. radio sales for the Telos Alliance. Workbench submissions are encouraged and qualify for SBE recertification credit. Email [email protected].