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

  • Sharp EL-531W vs. EL-531X Calculators

    (Typo in the permalink: should be W vs. X. Fixing it will break all the auto-linkies. Hate it when that happens.)

    When our lass first began using calculators, I put a pair of Sharp EL-531W calculators in harm’s way around the shop, where they still reside. The new EL-531X seems to have an identical key layout and internal logic (*), as well as the same under-ten-buck price, but I don’t like it nearly as much:

    Sharp EL-531W EL-531X calculators
    Sharp EL-531W EL-531X calculators

    It’s maybe 10 mm wider and doesn’t fit readily in my hand. I’m sure the rounded-rectangle stylin’ mimics a phone, but the cheapnified keys look ugly (particularly the ones around the arrow keys at the top) and don’t feel nearly as good.

    The new one fills a gap next to the lathe, where it should collect plenty of swarf.

    (*) Including engineering notation with multiple-of-three exponents, which I regard as vital.

  • Multimeter Banana Plugs

    The second banana plug on one of my multimeters failed, so I finally got around to replacing them with a dual plug from the Drawer o’ Banana Stuff:

    Dual banana plug - assembled
    Dual banana plug – assembled

    The bulky test leads don’t quite fit through the convenient retaining ring, so the zip tie holds ’em in place.

    A setscrew at the base of each banana jack tunnel crunches the test lead wire against the plug base, but, alone among the collection, this plug had one missing screw. Rather than toss it away (or, worse, back in the Drawer), I decided to Solve The Problem once and for ever:

    Dual banana plug - improvised clamp screw
    Dual banana plug – improvised clamp screw

    That’s an ordinary M3 screw from the Drawer o’ Random M3 Stuff with its head hacksawed off, a slot crudely hacksawed slightly off-center into the end, then lightly filed to hide the worst damage. With a bit of luck, nobody will ever notice it …

     

  • Knockoff RAMPS 1.4 Printer Controller Hardware Kit

    For 36 bucks delivered halfway around the planet, you can get a remarkable pile of gadgetry:

    RAMPS 1.4 - eBay parts
    RAMPS 1.4 – eBay parts

    With a bit of persuasion, it can become a 3D printer controller based on a RepRap RAMPS 1.4 shield or serve as a generic stepper / servo motor driver with three honkin’ MOSFET power switches, two thermistor inputs, a variety of I/O bits from the Arduino Mega PCB, and a monochrome LCD with a knob.

    The persuasion includes un-bending various header pins:

    RAMPS shield - bent pin
    RAMPS shield – bent pin

    Correcting bowlegged pin strips:

    And clipping offending pins:

    The interference between the bottom of the RAMPS power connector pin and the top of the Arduino Mega coaxial power jack seems baked right into the original PCB layout, which is puzzling. If you don’t trim the pins, this is as close as the boards will get:

    Well, of course, you could just jam all those headers together and bend the RAMPS PCB.

    The bent pin near the Reset button connects to the PS_ON output used to enable ATX-style power supplies. You connect the supply’s 5V_SBY always-on output to the VCC pin, which powers the Mega and most of the logic, but not the stepper motor outputs or the heaters.

    To make that work, remove D1 from the board where it’s snuggled along the header strip:

    RAMPS shield - D1 D2 locations
    RAMPS shield – D1 D2 locations

    D2, next to the fuse near the bottom of the picture, provides reverse-polarity protection for the RAMPS board.

    The servo motor power comes from the 5V pin. If you don’t need the PS_ON output and 5V_SBY input, then jumper the VCC and 5V pins together. Otherwise, you could solder-blob those pins on the bottom of the board, which means the servos are always powered.

    Configuring the latest 1.1.x version of Marlin should be straightforward …

  • Scrap Metal Prices

    Earlier this year, I finally hauled a pile o’ scrap metal to the recycler. For future reference, here’s what clattered down on the scale:

    Scrap Metal Prices - 2017-04
    Scrap Metal Prices – 2017-04

    I think the IRONY tag means ferrous bits & pieces in the mix. There’s a powerful motivation to hand them clean copper scrap, although I stop just after cutting off soldered pipe fittings and before stripping insulation.

    Memo to Self: Next time, ask about PCBs and gold-plated connectors.

  • Sandisk Extreme Pro MicroSD Card: End of Life?

    The Sandisk Extreme Pro 64 GB MicroSD card in the Sony HDR-AS30V died on the road once more, got reformatted, worked OK for a while, then kicked out catastrophic I/O errors after being mounted, so I swapped in the High Endurance card:

    Sandisk - 64 GB MicroSDXC cards
    Sandisk – 64 GB MicroSDXC cards

    The Extreme Pro still passes the f3probe tests, so it’s not completely dead, but if I can’t trust it in the helmet camera, it’s dead to me.

    It survived 17 months of more-or-less continuous use, although we didn’t do nearly enough riding for three months early this year. Call it 14 months x five rides / week x 1 hour / ride = 300 hours of recording. Multiply by 4 GB / 22.75 minutes to get 3 TB of video, about 50 times its total capacity.

    The never-sufficiently-to-be-damned Sony cards failed after less than 1 TB and 15-ish times capacity, making the Sandisk Extreme Pro much better. However, it’s painfully obvious these cards work better for low-intensity still-image recording, rather than continuous HD video.

    Using them as Raspberry Pi “hard drives” surely falls somewhere between still cameras and video, although Octoprint’s video snapshots and streaming media must make ’em sweat.

    We’ll see how Sandisk’s High Endurance memory works in precisely the application it’s labeled for.

  • Tenergy 18650 Lithium Cells: Initial Capacity

    The daytime running lights on the bikes get noticeably dimmer when the 18650 lithium cell voltage drops below 3.6 V, so I picked up a quartet of Tenergy protected cells and ran ’em through the battery tester:

    Tenergy 18650 Protected - 2017-08-04
    Tenergy 18650 Protected – 2017-08-04

    As with the ATX cells, the voltage decreases almost linearly with charge until it falls off the cliff near the end, but these have a higher terminal voltage throughout most of the curve, which is a Good Thing for LED flashlights.

    These four seem to have about the same overall capacity as the ATX cells, so we’ll run ’em all in sequence and see how long they last.

     

  • Wasabi NP-BX1 Batteries: FAIL

    I just got a new pair of Wasabi Power NP-BX1 batteries for the HDR-AS30V helmet camera, charged them up, and ran them through the CBA:

    Sony NP-BX1 - Wasabi FGHI - 2017-08-08
    Sony NP-BX1 – Wasabi FGHI – 2017-08-08

    Huh.

    The new ones (H and I) cost near twice as much as the 2-1/2 year old previous pair (F and G), while delivering less energy at a lower terminal voltage. Tested ’em twice to be sure and the curves overlay just about perfectly, so it’s not a fluke.

    The rep assures me the replacement cells will deliver their promised capacity. We shall see.