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.

Category: Electronics Workbench

Electrical & Electronic gadgets

  • Vacuum Tube LEDs: Fire in the Noval

    Replacing the original Noval socket in the string with the platter-friendly version, bracing the wiring with duct tape, balancing it on my desk, and firing it up:

    Noval socket - red phase
    Noval socket – red phase

    The green phase looks nice, too:

    Noval socket - green phase
    Noval socket – green phase

    Those screws are too big.

    The getter flash covers the entire top of the tube; shining an LED down through the evacuation tip won’t work and even a laser doesn’t do much. That saves me the trouble of trying to create a cap that doesn’t wreck the tube’s good looks.

    I originally planned to use white / natural PETG for the socket, but the more I see of those things, the more I think black is the new white. The sockets should vanish into the background, to let the tubes (and their reflections) carry the show.

    The (yet to be designed) base must vanish under the platter edge, too, which puts a real crimp on its overall height. I’m not sure how to fit an Arduino Pro Mini and an FTDI board beside the existing socket; perhaps this calls for a unified socket-base design held on by those screws, rather than a separate socket inside a base enclosure.

    Even though I know the tubes are inert and cool, I still hesitate before removing them from their sockets with the Neopixels running: you simply do not unplug a hot, powered device!

  • Vacuum Tube Prices, Then and Now

    Quite by coincidence, a Pile o’ Stuff disgorged a 1975 Radio Shack Catalog listing three dense pages of vacuum tubes, including a 21HB5A:

    Radio Shack 1975 Catalog - 21HB5A Tube Listing
    Radio Shack 1975 Catalog – 21HB5A Tube Listing

    These days, you buy New Old Stock 21HB5A tubes from eBay for about the same in current dollars with shipping:

    eBay - 21HB5A Tubes
    eBay – 21HB5A Tubes

    I should stock up and light up!

    Vacuum Tube LEDs - IBM 21HB5A Beam Power Tube - green violet phase
    Vacuum Tube LEDs – IBM 21HB5A Beam Power Tube – green violet phase

     

  • Streaming Player: Wireless Keypad

    Moving the streaming media player control panel across the Sewing Room for E-Z access:

    Wireless Keypad - colored labels
    Wireless Keypad – colored labels

    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.

  • Raspberry Pi Streaming Radio Player: Minimum Viable Product

    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:

    RPi Streaming Player - first lashup
    RPi Streaming Player – first lashup

    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:

    Numeric Keypad - stream labels
    Numeric Keypad – stream labels

    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!"
    view raw StreamingPlayer.py hosted with ❤ by GitHub

    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.

  • Makerspace Starter Kit Available

    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:

    This slideshow requires JavaScript.

    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:

    • Metal shop: old South Bend lathe / vertical mill-drill / bandsaw / hand tools / arbor press
    • Cabinets / shelves loaded with cutters / tools / micrometers / calipers / whatever
    • Gas & electric welding equipment, gas foundry furnace
    • Walls / bins / drawers of fasteners / wire nuts / plumbing fittings / pipe clamps / you-name-its
    • Bookshelves of references / magazines / databooks; I’ll keep at most one set of the magazines with my columns
    • Ham radio equipment / antennas / cables
    • Radial saw, blades, clamps, tooling, and a lumber / plywood stockpile
    • Labeled boxes of make-froms on steel shelving; you get the shelves, the boxes, and their contents.
    • Solvents, chemicals, metals, minerals, elements, etc.
    • Electronic / optical / mechanical surplus & doodads
    • Stockpiles of metal rods / pipes / beams / flanges / sheets / scrap parts
    • Tools & toys & treasures beyond your wildest imagination

    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.”

  • Maxell LR44 Cells: Packaging Glitch

    These look to be Maxell LR44 cells in OEM retail packaging, exactly as advertised, but … one cell seems odd:

    Maxell LR44 cells - hologram packages
    Maxell LR44 cells – hologram packages

    A closer look:

    Maxell LR44 cells - flipped cell
    Maxell LR44 cells – flipped cell

    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…

  • Kenmore Model 158: Older Foot Pedal Resistor

    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:

    Kenmore Model 158 - new-ish foot pedal resistor
    Kenmore Model 158 – new-ish foot pedal 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:

    Kenmore Model 158 - new-ish foot pedal connector
    Kenmore Model 158 – new-ish foot pedal connector

    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.