{
 "version": "2026-10-20",
 "license": "Dimension sheets are written by Xem Studio from the cited sources and are free to use (CC BY 4.0, attribute 'Xem Studio'). Linked files belong to their publishers under the license shown; Xem Studio does not host them. 'license_verified: false' means the license shown is from memory or the publisher's page as last read and should be confirmed at the link before commercial use.",
 "slug": "list-linear-alternator-module-2in-closed",
 "name": "Build list: Linear alternator module, 2 in, closed (sealed bounce space, chargeable)",
 "kind": "list",
 "category": "Electronics",
 "group": "Generators & alternators",
 "year": null,
 "question": "What parts do I need to build a Linear alternator module, 2 in, closed (sealed bounce space, chargeable)?",
 "tags": [
  "list",
  "build",
  "stirling",
  "long earth society",
  "tri-clamp",
  "linear alternator",
  "free piston",
  "test unit",
  "pressurised",
  "closed"
 ],
 "aliases": [
  "linear alternator module",
  "clamp in linear alternator",
  "tri clamp linear alternator",
  "free piston alternator test unit",
  "measure engine power linear alternator"
 ],
 "overall_mm": {
  "length": null,
  "width": null,
  "height": null
 },
 "official_cad": false,
 "xem_status": "not-scanned",
 "les": true,
 "free_files": 0,
 "url": "https://xemstudio.com/objects/list-linear-alternator-module-2in-closed/",
 "sheet_txt": "https://xemstudio.com/objects/list-linear-alternator-module-2in-closed/sheet.txt",
 "sheet": {
  "basis": "Every part is a free STEP/STL on this site or a standard part with its own page; quantities are the full count, every screw, nut, pin, gasket and clamp.",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "notes": [
   "One standard linear alternator that clamps in line on any 2 in sanitary device: a Ø48 clearance-seal piston on two spiral leaves, 40 magnets, the stator and coil outside the wall, ISO 2852 faces at both ends. Built once and moved between engines, so their power can be compared.",
   "Ø48 piston ±5 mm (±6 max) · moving mass 865 g · leaves 8851 N/m · Bl 28.8 N/A · coil 3.40 Ω, ≈25 mH · f₀ 16 Hz open, 19 Hz on 1 bar air, 36 Hz on 10 bar helium · 147.0 mm face to face · relief 15 bar g",
   "I wanted one alternator I build once and move from engine to engine: on top of a free-piston hot end, inside a thermoacoustic loop or ring, on a standing-wave engine, on anything that makes a pressure wave in a 2 in fitting. It is clamped like any sanitary fitting; nothing else holds it.",
   "It is the free-piston generator's alternator rearranged: the same stator, coil, magnets, leaves, half gaskets and collars, with the leaves at both ends of the magnets and nothing on the working side of the piston. The stack from face A: 42 mm bored spool (piston cup) · joint 1 with leaf 1 · 3 in bored spool (magnets inside, stator outside) · joint 2 with leaf 2 · 25.4 mm spool · face B.",
   "Face A takes the engine's pressure wave. Face B is the bounce space, closed by the four-port cap (fill, gauge, relief, and a plug or transducer); take the cap off and face B clamps straight onto another device, so the module can sit in the middle of a loop.",
   "Its own parameters, how to retune it and the measurement procedure are on the datasheet page. Leaf set A is the standard build; set B (soft leaves) and the mass discs are tuning parts.",
   "Charge through the fill valve slowly: the bounce space fills through the piston's clearance seal. Relief at 15 bar gauge; high-pressure bolted clamps and gaskets rated above it."
  ],
  "table": {
   "columns": [
    "subsystem",
    "object",
    "parts",
    "qty",
    "note"
   ],
   "rows": [
    [
     "",
     "linear-alternator-module-spools-2in",
     "spool-2in-42mm-bored-48.00",
     1,
     "face A (to the engine) and the piston's cylinder"
    ],
    [
     "",
     "tri-clamp-spool-bored-honed",
     "spool-2in-3in-bored-48.00",
     1,
     "the alternator section: magnet carrier inside, stator outside"
    ],
    [
     "",
     "linear-alternator-module-spools-2in",
     "spool-2in-25.4mm",
     1,
     "face B end: leaf 2's hub travel"
    ],
    [
     "",
     "tri-clamp-flexure-leaf",
     "leaf-2in-piston-t0.8",
     2,
     "choose one leaf set, A (standard 0.8): joints 1 and 2; leaf 2 turned over (opposite hand)"
    ],
    [
     "",
     "tri-clamp-leaf-half-gasket",
     "leaf-half-gasket-2in-w0.45",
     4,
     "choose one leaf set, A (standard 0.8): two per leaf, beads outward"
    ],
    [
     "",
     "linear-alternator-module-tuning-2in",
     "leaf-2in-piston-t0.5",
     2,
     "choose one leaf set, B (soft 0.5, tuning): joints 1 and 2 in place of the 0.8 leaves; leaf 2 turned over"
    ],
    [
     "",
     "tri-clamp-leaf-half-gasket",
     "leaf-half-gasket-2in-w0.6",
     4,
     "choose one leaf set, B (soft 0.5, tuning): two per soft leaf, beads outward"
    ],
    [
     "",
     "linear-alternator-module-mover-2in",
     "la-piston-cup-48x24",
     1,
     "in the 42 bored spool, crown toward face A"
    ],
    [
     "",
     "linear-alternator-module-mover-2in",
     "la-tube-rod-18x14x108.15",
     1,
     "pressed into the cup's socket; through both leaves"
    ],
    [
     "",
     "linear-alternator-module-mover-2in",
     "la-magnet-carrier-47x56",
     1,
     "pressed on the tube rod, centred under the stator"
    ],
    [
     "",
     "neodymium-disc-magnets",
     "magnet-12x3",
     40,
     "4 rows of 10 in the carrier, faces out: S, N, N, S from face A"
    ],
    [
     "",
     "fpse-hub-collars",
     "fpse-collar-18x28",
     4,
     "either side of each leaf's hub on the tube rod"
    ],
    [
     "",
     "set-screws-metric",
     "set-m3x4",
     4,
     "one grub per collar"
    ],
    [
     "",
     "fpse-linear-alternator-stator",
     "fpse-stator-pack-43deg",
     8,
     "round the 3 in bored spool at the magnets' centre"
    ],
    [
     "",
     "fpse-linear-alternator-stator",
     "fpse-bobbin-65",
     1,
     "between the teeth; slid over the spool's flange first"
    ],
    [
     "",
     "fpse-linear-alternator-stator",
     "fpse-coil-300t",
     1,
     "300 turns of 0.71 mm enamelled wire on the bobbin; the leads leave through the housing"
    ],
    [
     "",
     "fpse-linear-alternator-stator",
     "fpse-stator-housing-half",
     2,
     "clamp the packs onto the tube"
    ],
    [
     "",
     "socket-head-cap-screws-metric",
     "shcs-m4x20",
     4,
     "stator housing ears"
    ],
    [
     "",
     "hex-nuts-metric",
     "nut-m4",
     4,
     "stator housing ears"
    ],
    [
     "",
     "sanitary-high-pressure-clamp",
     "hp-clamp-2in",
     4,
     "bought: joints 1 and 2, face B (cap or next device) and face A (to the engine); rated above the 15 bar gauge relief setting"
    ],
    [
     "",
     "tri-clamp-gasket",
     "tc-gasket-2in",
     2,
     "Type B at face A (to the engine) and face B (under the cap); rated above the relief setting"
    ],
    [
     "",
     "tri-clamp-port-cap",
     "port-cap-2in-4x-npt18",
     1,
     "closes face B (the bounce space): fill valve, pressure gauge, relief valve, and a plug or pressure transducer; off when face B clamps into a loop"
    ],
    [
     "",
     "npt-thread-envelopes",
     "npt-1-8-male",
     4,
     "the 1/8 NPT stems of the fill valve, gauge, relief valve and plug (bodies are the builder's choice)"
    ],
    [
     "",
     "linear-alternator-module-tuning-2in",
     "la-mass-disc-41x26x4",
     4,
     "optional (tuning): add-on mass discs on the crown inside the cup, 0 to 4"
    ],
    [
     "",
     "socket-head-cap-screws-metric",
     "shcs-m3x20",
     3,
     "optional (tuning): hold 4 discs (3 × M3 × 16 for 3, × 12 for 2, × 8 for 1)"
    ],
    [
     "",
     "linear-alternator-module-2in-datasheet",
     "",
     1,
     "load resistor: non-inductive, power rated above the expected output; value on the datasheet: bought, not drawn"
    ],
    [
     "",
     "linear-alternator-module-2in-datasheet",
     "",
     1,
     "series capacitor: non-polar, C = 1/(ω² L) for the running frequency (datasheet), rated above the voltage across it: bought, not drawn"
    ]
   ]
  }
 },
 "sheet_text": "Build list: Linear alternator module, 2 in, closed (sealed bounce space, chargeable) — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/list-linear-alternator-module-2in-closed/  (CC BY 4.0)\nBasis: Every part is a free STEP/STL on this site or a standard part with its own page; quantities are the full count, every screw, nut, pin, gasket and clamp.\nCatalog version: 2026-10-20\n\nSizes: see table below\n- One standard linear alternator that clamps in line on any 2 in sanitary device: a Ø48 clearance-seal piston on two spiral leaves, 40 magnets, the stator and coil outside the wall, ISO 2852 faces at both ends. Built once and moved between engines, so their power can be compared.\n- Ø48 piston ±5 mm (±6 max) · moving mass 865 g · leaves 8851 N/m · Bl 28.8 N/A · coil 3.40 Ω, ≈25 mH · f₀ 16 Hz open, 19 Hz on 1 bar air, 36 Hz on 10 bar helium · 147.0 mm face to face · relief 15 bar g\n- I wanted one alternator I build once and move from engine to engine: on top of a free-piston hot end, inside a thermoacoustic loop or ring, on a standing-wave engine, on anything that makes a pressure wave in a 2 in fitting. It is clamped like any sanitary fitting; nothing else holds it.\n- It is the free-piston generator's alternator rearranged: the same stator, coil, magnets, leaves, half gaskets and collars, with the leaves at both ends of the magnets and nothing on the working side of the piston. The stack from face A: 42 mm bored spool (piston cup) · joint 1 with leaf 1 · 3 in bored spool (magnets inside, stator outside) · joint 2 with leaf 2 · 25.4 mm spool · face B.\n- Face A takes the engine's pressure wave. Face B is the bounce space, closed by the four-port cap (fill, gauge, relief, and a plug or transducer); take the cap off and face B clamps straight onto another device, so the module can sit in the middle of a loop.\n- Its own parameters, how to retune it and the measurement procedure are on the datasheet page. Leaf set A is the standard build; set B (soft leaves) and the mass discs are tuning parts.\n- Charge through the fill valve slowly: the bounce space fills through the piston's clearance seal. Relief at 15 bar gauge; high-pressure bolted clamps and gaskets rated above it.\n\nsubsystem  object  parts  qty  note\n  linear-alternator-module-spools-2in  spool-2in-42mm-bored-48.00  1  face A (to the engine) and the piston's cylinder\n  tri-clamp-spool-bored-honed  spool-2in-3in-bored-48.00  1  the alternator section: magnet carrier inside, stator outside\n  linear-alternator-module-spools-2in  spool-2in-25.4mm  1  face B end: leaf 2's hub travel\n  tri-clamp-flexure-leaf  leaf-2in-piston-t0.8  2  choose one leaf set, A (standard 0.8): joints 1 and 2; leaf 2 turned over (opposite hand)\n  tri-clamp-leaf-half-gasket  leaf-half-gasket-2in-w0.45  4  choose one leaf set, A (standard 0.8): two per leaf, beads outward\n  linear-alternator-module-tuning-2in  leaf-2in-piston-t0.5  2  choose one leaf set, B (soft 0.5, tuning): joints 1 and 2 in place of the 0.8 leaves; leaf 2 turned over\n  tri-clamp-leaf-half-gasket  leaf-half-gasket-2in-w0.6  4  choose one leaf set, B (soft 0.5, tuning): two per soft leaf, beads outward\n  linear-alternator-module-mover-2in  la-piston-cup-48x24  1  in the 42 bored spool, crown toward face A\n  linear-alternator-module-mover-2in  la-tube-rod-18x14x108.15  1  pressed into the cup's socket; through both leaves\n  linear-alternator-module-mover-2in  la-magnet-carrier-47x56  1  pressed on the tube rod, centred under the stator\n  neodymium-disc-magnets  magnet-12x3  40  4 rows of 10 in the carrier, faces out: S, N, N, S from face A\n  fpse-hub-collars  fpse-collar-18x28  4  either side of each leaf's hub on the tube rod\n  set-screws-metric  set-m3x4  4  one grub per collar\n  fpse-linear-alternator-stator  fpse-stator-pack-43deg  8  round the 3 in bored spool at the magnets' centre\n  fpse-linear-alternator-stator  fpse-bobbin-65  1  between the teeth; slid over the spool's flange first\n  fpse-linear-alternator-stator  fpse-coil-300t  1  300 turns of 0.71 mm enamelled wire on the bobbin; the leads leave through the housing\n  fpse-linear-alternator-stator  fpse-stator-housing-half  2  clamp the packs onto the tube\n  socket-head-cap-screws-metric  shcs-m4x20  4  stator housing ears\n  hex-nuts-metric  nut-m4  4  stator housing ears\n  sanitary-high-pressure-clamp  hp-clamp-2in  4  bought: joints 1 and 2, face B (cap or next device) and face A (to the engine); rated above the 15 bar gauge relief setting\n  tri-clamp-gasket  tc-gasket-2in  2  Type B at face A (to the engine) and face B (under the cap); rated above the relief setting\n  tri-clamp-port-cap  port-cap-2in-4x-npt18  1  closes face B (the bounce space): fill valve, pressure gauge, relief valve, and a plug or pressure transducer; off when face B clamps into a loop\n  npt-thread-envelopes  npt-1-8-male  4  the 1/8 NPT stems of the fill valve, gauge, relief valve and plug (bodies are the builder's choice)\n  linear-alternator-module-tuning-2in  la-mass-disc-41x26x4  4  optional (tuning): add-on mass discs on the crown inside the cup, 0 to 4\n  socket-head-cap-screws-metric  shcs-m3x20  3  optional (tuning): hold 4 discs (3 × M3 × 16 for 3, × 12 for 2, × 8 for 1)\n  linear-alternator-module-2in-datasheet    1  load resistor: non-inductive, power rated above the expected output; value on the datasheet: bought, not drawn\n  linear-alternator-module-2in-datasheet    1  series capacitor: non-polar, C = 1/(ω² L) for the running frequency (datasheet), rated above the voltage across it: bought, not drawn\n\nFiles elsewhere (not hosted by Xem Studio; license as stated by the publisher):\n- Long Earth Society: Engine builds — web, video — LES site — https://longearthsociety.com/engineering/\n\nXem Studio scan: not planned; the official CAD above covers it.\nAPI: https://xemstudio.com/api/geometry?object=list-linear-alternator-module-2in-closed\n",
 "sources": [
  {
   "publisher": "Long Earth Society",
   "title": "Engine builds",
   "url": "https://longearthsociety.com/engineering/",
   "formats": [
    "web",
    "video"
   ],
   "license": "LES site",
   "license_verified": true,
   "hosted": false
  }
 ],
 "xem": {
  "status": "not-scanned",
  "sheet_free": true,
  "mesh_price_usd": null,
  "step_price_usd": null,
  "tolerance_mm": null
 },
 "related": [
  "linear-alternator-module-2in-datasheet",
  "list-linear-alternator-module-2in-open",
  "linear-alternator-module-mover-2in",
  "linear-alternator-module-spools-2in",
  "linear-alternator-module-tuning-2in",
  "fpse-linear-alternator-stator",
  "tri-clamp-flexure-leaf",
  "sanitary-high-pressure-clamp",
  "list-fpse-generator-2in"
 ],
 "fits": [],
 "dimensions": "exact (nominal, no printing tolerance)",
 "dimension_rule": "All geometry on Xem Studio is exact (nominal, true size) with no printing tolerance. Where a part meets another part, the object lists its mating features (feature, exact size, what it mates with, fit class: press, slide, run, socket, clamp or designed). Apply your process's allowance to those features only; 'designed' gaps are part of the design and stay as drawn.",
 "mating": [],
 "faq": [
  {
   "q": "Why one standard unit?",
   "a": "Moved between engines with the same load, it turns 'which engine is better' into a measurement: the unit's own mass, springs, losses and Bl are the same every time and are on the datasheet."
  },
  {
   "q": "What engines does it fit?",
   "a": "Anything with a 2 in ferrule carrying a pressure wave: a free-piston Stirling hot end, a thermoacoustic loop, ring or standing-wave engine. On a ring or loop, face B clamps to the next part instead of the cap."
  },
  {
   "q": "What must the clamps and gaskets be rated for?",
   "a": "Above the 15 bar gauge relief at their temperature. High-pressure bolted 2 in clamps are published at 1000 psi (69 bar) at 70–75 °F."
  },
  {
   "q": "Where is the electricity?",
   "a": "Two leads from the coil outside the vessel: no wire passes the pressure boundary. Always connect the load before the engine runs."
  }
 ],
 "files_license": null,
 "offers": [],
 "markdown": "https://xemstudio.com/objects/list-linear-alternator-module-2in-closed/index.md"
}