24 November 2005

$2000 saved in about ten minutes

Customer’s first non-CBD office requires music on hold. Customer asks ’phone installer what to use; response is “anything will do” and when pressed suggests a music-on-hold service which just happens to have a AUD$2000 flagfall plus serious ongoing costs.

Customer then asks Leon if he has a solution. “What are you using now?” Turns out to be a laptop running Windows 2000, XMMS and an MP3 file — all of which requires rebooting every few weeks. OK, so SCP the MP3 file onto the country server, unpack it into a WAV to reduce CPU usage (not that it’s significant any on a 3GHz Athlon64), enable the sound card in the BIOS (I disable any device not in use, as it simplifies things, makes them more reliable and frees up IRQs), run alsaplayer over it and we’re away.

Elapsed time: ten minutes. Value to customer: ≅AUD$12,000 an hour. ♥ Woh! Ah feel goood... oh, I knew that I would, yeah... ♥ (-:

So... why not do the same in Perth?

When we try, we get silence, yet we can plug powered speakers into the same green socket on the server and get a nice clear audio holding pattern.

The country branch’s PABX has a 3.5mm stereo plug, the city branch has a 3.5mm-to-3.5mm extender cable plugged into a 3.5mm inline socket soldered onto the end of an RJ12 (telephone) cord. Untwisting the 3.5mm socket reveals that it is a mono 3.5mm socket, so it shorts the right-hand channel to ground when a stero plug is inserted.

Since the laptop is driving the cable from a “headphone” socket, resistors are involved which protect the laptop from the consequences of this electric vandalism; the server’s audio drivers, on the other hand, shut down when one channel is shorted. Round of applause for that chip designer, good call.

To add insult to injury, the cable inside the 3.5mm socket is poorly soldered and employs zero strain relief, not to mention that the RJ12 socket is wired up (colour coded) backwards WRT every other RJ12 cable I can find (ie YRGK instead of KGRY).

So... off to Tricky Dicky’s for a 3.5mm stereo plug and a longer RJ12 cable. 5 minutes with a soldering iron, and our shiny new cable works first time, every time. Not only that, it looks a lot neater as well. The old cable celebrates retirement by parting the last few threads of soldered copper, and is soon on the way to the circular file.

Now customer has a spare laptop. 128MB of RAM, 10GB of HDD, and a slow CPU. Perhaps it can run some old games?

No comments: