sound voodoo and decrepit vintage Macintoshes
Thursday, October 29 2015
One of my goals today was to hammer out a few little issues with my Ahmed-Mohamed-inspired clock before the weekend's Halloween festivities. The main remaining issue was the audio quality and volume. As you may recall, I'm using a WTV020-SD-16P chip to play audio clips from a microSD card. But the WTV020-SD-16P is one of the most cantankerous, voodoo-prone devices ever to be attached to an Arduino. I'd been playing audio files successfully, but only after editing them in Audacity to make them much quieter than they had been. Even then, if I played them too loudly on my clock, the amplifier (which is, mind you, a separate device) would starve the circuitry of enough available power that the playback would crash, often before it could even start. The solution seemed to be to implement two power supplies, but for some reason the device continued crashing even with that. I even installed a big 7805 five volt regulator (complete with custom copper heatsink), but still the crashing kept happening. In desperation, I soldered a big thick wire directly between the Arduino Nano and the new 7805, and wow, suddenly the audio started working reliably. Satisfied, I stopped working on the clock for awhile.
The day was so sunny and warm that I never needed to start a fire in the woodstove. I took advantage of the nice weather by cutting my hair, which hadn't been cut for almost a whole year and was down to my shoulders. I sometimes like the way I look in long hair, but in terms of comfort, I usually fucking hate it. For example, while working on my clock earlier today, some of my hair got caught in the hinge of my glasses which were, as always, drifting slowly like a glacier down my nose. When the glasses started tugging the hair from my scalp, I knew I had to do something about it. As always, I cut it mostly by touch, feeling for long patches, cutting them back, and flinging the salt-and-pepper-colored material into the vegetation. Later, I touched it up a little in a mirror, though the way it looked in the back was going to have to be a mystery. The change can be seen in my Facebook profile pictures:
The way I looked this weekend.
The way I look now.
Later, back in the house, I was dicking around with my clock again and damned if the audio wasn't crapping out on me again. The thing was cursed! I tried other combinations of power supplies, bringing in other ones and leveraging the tiny 5 volt regulator built into the Arduino Nano's board. Some things seemed to work for a time, but inevitably the crapping-out would return. What was I going to do? I wanted the audio to be loud enough to be heard, say, on the street in Woodstock during the crowded Halloween thing that happens there every year. While tinkering with it (for example, adding capacitors across the power rails and even trying different methods for deliving 3.3 volts to the WTV020-SD-16P), I accidentally attached 12 volts to the reset pin, which was a big mistake. Atmega328s are tough & forgiving, but not that kind of tough & forgiving. Still, the clock seemed to work okay, for awhile. But then odd things started happening. The battery-powered real time clock kept resetting back to its default time. And when I went to upload a new version of the firmware, I kept getting avrdude verification errors, and even reinstalling the bootloader did no good. Fortunately, the Arduino Nanos I buy from China cost about the same as a happy hour Budweiser, so I eventually just abandoned the one I couldn't reflash, soldered header pins on another one (for this installation, those pins go in upside-down) and used that. Miraculously, this seemed to fix all my problems, including the one with crapping-out audio.
Meanwhile, Gretchen had been trying to recover files from an old floppy disk dating to her undergraduate years in Oberlin (ending in 1992). She'd been impressed that I actually had a USB floppy drive on hand, but this soon proved incapable of reading the disk. Eventually it dawned on me that the disk probably had the old Macintosh GCR double-density format, which isn't readable on modern equipment. Fortunately, I have an old Macintosh Performa 475 with a built-in floppy drive that should be able to read such disks, but I hadn't fired that up in years.
My first attempts to boot up the old mac failed, but removing and reinstalling the memory cards was the only fixing it seemed to need. It booted to its old System 7 Desktop, and even attempted to read Gretchen's disk when I inserted it. But then all it would do was offer to format it. Trying to read other floppies resulted in the same offer, suggesting the drive had died from all the years of disuse. So I dug into the laboratory's deep storage to get the old MacSEs I knew were back there. One of these actually booted, though it only did this once, before I had a chance to attach a keyboard and mouse. After that, it would not boot. So I opened it up and extracted its floppy drive and attached it to the Performa 475. But it was in much worse mechanical shape than the Performa 475's floppy drive had been. It could load a disk, but just barely, and then its mechanical parts made funny noises before grinding to a halt. That's all a long and round-about way of saying I do not currently have the vintage technology to read GCR-formatted Macintosh flopppy drives. It's a good thing I rescued the content of most of my old Mac floppies back when this old equipment still worked reliably (which was not quite five years ago).
Between my clock tinkering, my dive into vintage Macintosh hardware, and some much-procrastinated web development work, I ended up staying up until past 2:00am.
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