The Smell of Molten Projects in the Morning
Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.
Electrical & Electronic gadgets
Quite by coincidence, a Pile o’ Stuff disgorged a 1975 Radio Shack Catalog listing three dense pages of vacuum tubes, including a 21HB5A:
These days, you buy New Old Stock 21HB5A tubes from eBay for about the same in current dollars with shipping:
I should stock up and light up!
Moving the streaming media player control panel across the Sewing Room for E-Z access:
Stipulated: garish labels that don’t fit the keys well at all.
I need more than one stream for testing; the only one that matters is Classical.
The keypad uses the same 2.4 GHz ISM band as the Raspberry Pi’s Wifi radio, which means holding a key down (which should never happen) puts a dent in mplayer’s cache fill level. Even absent that interference, the WiFi link seems more than a little iffy, probably because it’s at the far end of the house and upstairs from the router.
Other WiFi devices report that 2.4 GHz RF has trouble punching through the intervening fifty feet of hardwood floor (on the diagonal, the joists amount to a lot of wood) and multiple sets of doubled wallboard sheets; the RPi probably needs a better radio with an actual antenna. I did move the WiFi control channel away from the default used by the (relatively distant) neighbors, which seemed to improve its disposition.
With the numeric keypad producing events, and the USB audio box producing sound, the next steps involve starting mplayer through Python’s subprocess interface and feeding keystrokes into it.
There’s not much to it:
As much hardware doc as you need:
The green plug leads off to a set of decent-quality PC speakers with far more bass drive than seems absolutely necessary in this context. The usual eBay vendor bungled an order for the adapter between the RCA line-out jacks and the 3.5 mm plug that will avoid driving the speakers from the UCA202’s headphone monitor output; I doubt that will make any audible difference. If you need an adapter with XLR female to 1/4 inch mono, let me know…
The keypad labels provide all the UI documentation there is:
The Python source code as a GitHub Gist:
| from evdev import InputDevice,ecodes,KeyEvent | |
| import subprocess32 | |
| Media = {'KEY_KP7' : ['mplayer','http://relay.publicdomainproject.org:80/classical.aac'%5D, | |
| 'KEY_KP8' : ['mplayer','http://relay.publicdomainproject.org:80/jazz_swing.aac'%5D, | |
| 'KEY_KP9' : ['mplayer','http://live.str3am.com:2070/wmht1'%5D, | |
| 'KEY_KP6' : ['mplayer','http://pubint.ic.llnwd.net/stream/pubint_wamc'%5D, | |
| 'KEY_KP1' : ['mplayer','-playlist','http://dir.xiph.org/listen/5423257/listen.m3u'%5D, | |
| 'KEY_KP2' : ['mplayer','-playlist','http://dir.xiph.org/listen/5197460/listen.m3u'%5D, | |
| 'KEY_KP3' : ['mplayer','-playlist','http://dir.xiph.org/listen/5372471/listen.m3u'%5D, | |
| 'KEY_KP0' : ['mplayer','-playlist','http://dir.xiph.org/listen/5420157/listen.m3u'%5D | |
| } | |
| Controls = {'KEY_KPSLASH' : '/', | |
| 'KEY_KPASTERISK' : '*', | |
| 'KEY_KPDOT' : ' ' | |
| } | |
| k=InputDevice('/dev/input/keypad') | |
| print 'Starting mplayer' | |
| p = subprocess32.Popen(Media['KEY_KP7'],stdin=subprocess32.PIPE) | |
| print ' … running' | |
| for e in k.read_loop(): | |
| if (e.type == ecodes.EV_KEY) and (KeyEvent(e).keystate == 1): | |
| kc = KeyEvent(e).keycode | |
| if kc == 'KEY_NUMLOCK': | |
| continue | |
| print "Got: ",kc | |
| if kc == 'KEY_BACKSPACE': | |
| print 'Backspace = shutdown!' | |
| p = subprocess32.call(['sudo','halt']) | |
| break | |
| if kc in Controls: | |
| print 'Control:', kc | |
| p.stdin.write(Controls[kc]) | |
| if kc in Media: | |
| print 'Switching stream to ',Media[kc] | |
| print ' … halting' | |
| p.communicate(input='q') | |
| print ' … restarting' | |
| p = subprocess32.Popen(Media[kc],stdin=subprocess32.PIPE) | |
| print ' … running' | |
| print "Out of loop!" |
The Media dictionary relates keycodes with the command line parameters required to fire mplayer at the streaming stations. With that running, the Controls dictionary turns keycodes into mplayer keyboard controls.
There’s no display: you have no idea what’s going on. I must start the program manually through an ssh session and can watch mplayer‘s console output.
Poking the Halt button forcibly halts the RPi, after which you squeeze the Reset button to reboot the thing. There’s no indication that it’s running, other than sound coming out of the speakers, and no way to tell it fell of the rails other than through the ssh session.
The loop blocks on events, so it can’t also extract stream titles from the (not yet implemented) mplayer stdout pipe / file and paste them on the (missing) display; that’s gotta go.
There’s a lot not to like about all that, of course, but it’s in the tradition of getting something working to discover how it fails and, in this case, how it sounds, which is even more important.
For a variety of reasons that aren’t relevant here, I must dramatically reduce the amount of stuff in the Basement Laboratory / Machine Shop / Warehouse.
If you (or someone you know) has / is starting / will start a makerspace or similar organization, here’s an opportunity to go from zero to hero with a huge infusion of tools / instruments / make-froms / raw material / gadgets / surplus gear.
Think of it as a Makerspace Starter Kit: everything you need in one acquisition.
You’ve seen much of the stuff in these blog posts during the past five years, although I tightly crop the photos for reasons that should be obvious when you consider the backgrounds.
A few glimpses, carefully chosen to make the situation look much tidier than it really is:
I’m not a hoarder, but I can look right over the fence into that territory…
I want to donate the whole collection to an organization that can figure out how to value it and let me write it off. Failing that, I’m willing to sell the whole collection to someone who will move it out and enjoy it / put it to good use / part it out / hoard it.
We can quibble over the value, which surely lies between scrap metal and filet mignon.
As nearly as I can estimate from our last two moves, I have 6±2 short tons of stuff:
When we left Raleigh, the moving company estimator observed “This will be like moving a Home Depot!”
You must take everything, which means you must have the ability & equipment to handle 6±2 tons of stuff in relatively small, rather heavy, not easily stackable lumps. You’ll need 1000+ square feet of space with at least a seven-foot ceiling on your end to unload the truck(s) and create a solid block of stuff with skinny aisles between the shelves. This is not a quick afternoon trip for you, your BFF, a pickup truck, and a storage unit.
I plan to keep the Sherline, the M2 3D printer, various small tools, some hardware / parts / stock, most of the electronic instruments (antique-ish, at best) and components, plus odds and ends. I’ll extract or clearly mark those items, leaving your team to move everything else without (too many) on-the-fly decisions.
I can provide photos and descriptions, but, realistically, you should evaluate the situation in person.
Although we’re not planning to move in the near future, if you’re thinking of moving into the Mid Hudson Valley and always wanted a house with a ready-to-run Basement Shop, we can probably work something out. Note: all of the online real estate descriptions, including Zillow, seem confused, as the two houses on our two-acre property contain the total square footage / rooms / baths / whatever. Contact us for the Ground Truth after you’ve contemplated the satellite view.
As the saying goes, “Serious inquiries only.”
These look to be Maxell LR44 cells in OEM retail packaging, exactly as advertised, but … one cell seems odd:
A closer look:
The production values seem high enough to suggest that they’re Genuine Maxell products, hologram packaging and all, but you’d expect the Maxell end-of-line QC should pick out a flipped cell.
If one were the wondering sort, though, one might wonder why the Maxell USA website search function doesn’t return any mention of LR44 cells…
Based on the paperwork tucked into the sewing table, the most recent Kenmore Model 158 sewing machine in our stable dates to 1972, a bit earlier than the others, and has a metal-cased foot pedal with a wire-wound resistor:
The cord insulation stiffened up over the decades and I wanted to replace it, but the contacts in the sewing machine connector were spot-welded to the conductors with no room for teeny screws:
I blew out the fuzz, put it back together, and it works pretty well, modulo the usual low torque at slow speeds issue.
The discrete resistor taps produce a somewhat stepped response, but early reports suggest it’s not enough to be annoying; it’s much more stable than the carbon disks in the more recent pedals.
The weakest fluorescent shop light fixtures always fail during cold weather (apart from the usual early tube failures) and this winter’s cold spells triggered the usual carnage, so I picked up half a dozen (cheap) 22 W LED T8 tubes and set about rewiring three defunct (cheap) fluorescent fixtures from the recycle heap. The new LED tubes run directly from the AC line; you must remove the fluorescent fixture’s ballasts / capacitors / starters and rewire the “tombstone” lampholders accordingly.
The first challenge, as always, involved taking the fixtures apart. Turns out prying the endcap away from the fixture enough to clear the pair of bumps punched into the metal does the trick:
Each endcap contains the ballast inductor / choke and power-factor correction capacitor for one tube. The inductors from one shoplight had a fancy plastic tab that might have held the capacitor in place, but that’s about the only difference:
The 150 kΩ resistor has its leads twisted around the capacitor leads without benefit of that fancy solder stuff one might think necessary for a good connection.
The capacitor contacts use the minimum possible amount of material:
I think the caps use metallized Mylar film, but who knows?
The inductors measure 280 mH and the caps a whopping 5 µF. I might trust the inductors in a low-voltage circuit, but the caps have no redeeming features and went directly to the trash.
The starter PCB lived in the center of the fixture:
I deliberately picked LED tubes with the AC line contact on one end and the neutral contact on the other, so as to not put line and neutral contacts in the same tombstone. After rewiring, the neutral endcap looks like this:
The other endcap holds the power cord and has a green earth ground wire snaking out to a little tab passed into a slot punched in the metal case. I replaced the tab with an actual screw / solderless connector / toothed washer, but have no pix to show for it.
The LED tubes run at 6500 K and contrast harshly with the warm-white tubes in the fluorescent shoplights. I went with the highest light output, because even the best (cheap) LED tubes produce barely half the output of the fluorescents: 2000-ish lumens vs 3900-ish.
The Smell of Molten Projects in the Morning 