Readiness report
Superb Lab Power Supply · 2026-09-03 00:13 · complete · 85 searches, 5 pages fetched
Cybersecurity — software & network: Could not check · 2 findings
Details in the Cybersecurity section of the report below.
Readiness: Superb Lab Power Supply
Verdict: At risk · 2026-09-02 · est. parts cost $220–$420 Cybersecurity — software & network: Could not check
One part now blocks a clean build: R4, the Vishay WSL3637R0100FEA 10 mΩ four-terminal Kelvin shunt on the custom 00002A shield. It is out of stock at all five ECIA-authorized distributors that list it, with 40–55 week factory lead times, and every sibling in the same 3637 package (FEB, DEA, FBA) is out of stock everywhere too — so there is no drop-in to fall back on. That shunt sits in the full 3 A output path and the snapshot rates its substitution latitude "Low", so it cannot simply be swapped for a different package. The mains power switch and the chassis ground lug are also zero-stock with 3–15 week leads, though both have generic equivalents. Everything else is sourceable today, and where a part went obsolete (the relay, the 100 nF decoupling caps, the 1.8 MΩ divider resistor) there is a substitute below with its footprint checked against distributor parametrics. Note that the analog 0–30 V board is bought as a kit ($4.25–$17) that supplies its own parts — only the shield is built component by component, which is exactly where the shunt problem lands. The verdict has dropped from the previous report's Ready with caveats: in July the shunt was still in stock at a specialist distributor at $1.05, and the mains switch had not been checked. The cost estimate also rose sharply, because the previous report priced a generic $25.67 transformer rather than the specified DP-241-8-20 ($46–$49) and did not count the chassis consumables (wire, cord, fasteners, standoffs, lettering, ground lug) at all.
Action required
| Part | Problem | Recommended action |
|---|---|---|
| R4 WSL3637R0100FEA | New since July. Zero stock at all 5 ECIA distributors; 40–55 week leads. Every WSL3637 10 mΩ sibling also zero-stock. | Order now against lead time, or source from a broker and verify authenticity. Do not swap to a 4527-package shunt — the board is drawn for the 3637 Kelvin pads. |
| C3–C7 GRM188R71H104KA93D | Obsolete; zero stock everywhere; 42-week lead. | Use C0603C104K5RACTU (KEMET), $0.13, 7.1 M in stock — verified 0603 drop-in. |
| C2 GRM188R61A106KE69D | Zero stock at all 4 distributors; 19-week lead. | Use C1608X5R1A106K080AC (TDK), $0.27, 160 k in stock — verified 0603 drop-in. |
| R5 ERJ-3EKF1804V | Obsolete at DigiKey (30-week lead). | Buy from Newark (10,828 @ $0.032) or use CRCW06031M80FKEA, $0.10, 27,898 in stock. |
| K1 G5LE-1-VDDC12 | Obsolete (as in July), zero stock at DigiKey. | Still stocked by Heilind/Sager/ICC/TTI. Or use G5LE-1 DC12 / G5LE-14 DC12 — footprint not verified, check the pinout. |
| IC1 MAX44284FAUT+T | New since July. DigiKey stock fell to zero (22-week lead). | Order from Mouser: 6,115 in stock @ $3.66. |
| Item 11 EG4397-ND switch | New since July. Zero stock, 15-week lead, single distributor. Its 19.20 × 13.00 mm cutout also disagrees with the panel file. | Back-order at DigiKey, or use a switched-and-fused C14 inlet (~$5–7) and drop the separate switch. |
| Item H L35-B2-5 ground lug | New since July. Zero stock at all 5 distributors, 3–12 week leads, $14–$17. | Any UL-listed 8–14 AWG mechanical copper lug works; electrical-supply houses list the base Blackburn L35 at $3.29. |
| Item 14 enclosure | New since July. No enclosure checked meets the ≥200 × 210 × 90 mm envelope. | Select manually against the envelope; the Hammond 1455ZT2201 is 34 mm too short. |
| Item 9 DP-241-8-20 | Not a shortage — a price correction. Exact part is $46–$49, not the $25.67 assumed in July. | Budget for it; must be an AC-AC chassis transformer, never a DC brick. |
Cybersecurity — software & network
Could not check — All three software components are unpinned Arduino-side code with no vulnerability database covering them, so no security check was possible; the two problems recorded here are a dead download link and unpinned versions, not network exposure - this device has no network interface.
| Component | Version | How known | Support status |
|---|---|---|---|
| Arduino Core for AVR (arduino:avr) | not determined | unpinned (the lab ships no board-package manifest; the snapshot records no version) | — |
| Arduino Wire library (<Wire.h>, I2C master) | not determined | unpinned (bundled with whichever AVR core is installed; included at DCmeter.ino line 1) | — |
| LiquidCrystal_I2C (fmalpartida new-liquidcrystal fork) | not determined | unpinned (DCmeter.ino line 2 cites a bare Bitbucket downloads directory with no version; the maintained GitHub mirror's library.json currently publishes 1.5.0) | — |
| Component | Finding | Severity | Fix available? |
|---|---|---|---|
| Arduino firmware dependencies (AVR core, Wire, LiquidCrystal_I2C) | None of the three firmware dependencies is pinned to a version, and the sketch uses a constructor that only this LCD fork provides, so a student who installs the Library Manager's LiquidCrystal_I2C instead gets a compilation failure rather than a working meter. | posture | Mitigation only - state the exact library and core versions in the build instructions and ship a vendored copy of the LCD library with the lab |
| LiquidCrystal_I2C (fmalpartida new-liquidcrystal fork) | The library download location the firmware source cites returns HTTP 404, so anyone building this lab has to find the LCD driver somewhere else on the internet and cannot check that what they got is what the lab was written against. | posture | Mitigation only - take the library from the maintained GitHub mirror at github.com/fmalpartida/New-LiquidCrystal (its library.json publishes 1.5.0) and keep that copy with the lab materials instead of linking out |
What this means for your lab
This power supply is not a networked device. The Arduino talks to a bench PC over a USB serial cable only, and the 0x3F and 0x68 numbers in the design are I2C chip addresses on a few centimetres of wire inside the box, not network addresses. So there is nothing here for someone else on your campus network to reach, log into, or read, and nothing needed to be cleared with IT before the supply is switched on. The real problem is where the firmware's code comes from. The one third-party library the sketch needs is fetched from a link printed in the source file, that link is dead, and nothing records which version the lab was written against - so each student ends up downloading some copy of the library from wherever they can find it, and the common one from the Arduino Library Manager will not even compile against this sketch. Before the next class, download the library once from the maintained GitHub mirror, keep that copy alongside the lab files, and write the version you used into the build instructions so everyone compiles the same code.
Not checked
- Arduino Core for AVR (arduino:avr): no vulnerability database covers Arduino board packages, and no version is pinned to check
- Arduino Wire library (<Wire.h>): bundled with the AVR core; it has no version of its own and no advisory database
- LiquidCrystal_I2C (fmalpartida new-liquidcrystal fork): no advisory database covers Arduino libraries, the lab pins no version, and the documented download location is gone
- Arduino IDE and the avr-gcc toolchain: implied by the AVR core but not recorded with a version in the lab materials, and not tracked by endoflife.date
- EAGLE (00002A.sch, 00002A.brd) and the SVG editor for frontPanel.svg: design-tool dependencies implied by the lab's file formats; no version recorded and no advisory database applies
Parts
Integrated Circuits and Active Semiconductors (00002A shield)
| Part | Spec/Package | Status | Stock | Price | Source | Drift |
|---|---|---|---|---|---|---|
| IC1: MAX44284FAUT+T | Current-sense amp, 1.7–5.5 V, SOT-23-6 | Available (not at DigiKey) | 6,115 (Mouser) | $3.66 | Mouser (ECIA); DigiKey $3.99, stock 0, 22-wk lead | DigiKey 2,773 → 0; price held at $3.66 |
| IC2: MCP3422A0-E/SN | 18-bit ADC, 2.7–5.5 V, SOIC-8 | Ready | 2,599 | $3.72 | DigiKey | 4,069 → 2,599; price flat |
| IC3: MCP6061T-E/OT | Op-amp, 1.8–6.0 V, SOT-23-5 | Ready | 2,829 | $0.84 | DigiKey | 574 → 2,829; price flat |
| Q1, Q2: BC817-25LT3G | NPN 45 V / 500 mA, SOT-23-3 | Ready | 139,400 | $0.17 | DigiKey (9 distributors stocked) | 3,187 → 139,400; price flat |
| D3: BAT54 | Schottky 30 V / 200 mA, SOT-23-3 | Ready | 842,137 | $0.14 | DigiKey (BAT54LT1G single-die variant) | 424,390 → 842,137; price flat |
| Z1: 824501361 | TVS 36 V standoff, 400 W, DO-214AC | Ready — polarity unconfirmed | 4,033 | $0.29 | DigiKey (listed as SMAJ36CA); Mouser 2,631 on the exact number | 4,611 → 4,033; price flat |
Electromechanical and Relays (00002A shield)
| Part | Spec/Package | Status | Stock | Price | Source | Drift |
|---|---|---|---|---|---|---|
| K1: G5LE-1-VDDC12 | SPDT 1 Form C, 12 VDC coil, 10 A, through hole | Obsolete — still stocked elsewhere | 0 at DigiKey; 1,760 Heilind, 607 Sager, 586 ICC, 475 TTI | $1.07 list; $0.67–$0.77 at stocking distributors | ECIA | Was "obsolete, no source"; four authorized distributors do hold stock |
Precision Current Shunt Resistor (00002A shield)
| Part | Spec/Package | Status | Stock | Price | Source | Drift |
|---|---|---|---|---|---|---|
| R4: WSL3637R0100FEA | 10 mΩ, 1%, 3 W, 3637 Kelvin, 9.14 × 9.40 mm | Hard to obtain | 0 at all 5 ECIA distributors (40–55 wk leads) | $1.46 | DigiKey (back-order only) | Was >100 @ $1.05 at a specialist distributor; now no stock anywhere |
Passive Components — Resistors and Capacitors (00002A shield)
| Part | Spec/Package | Status | Stock | Price | Source | Drift |
|---|---|---|---|---|---|---|
| R5: ERJ-3EKF1804V | 1.8 MΩ, 1%, 0603 | Obsolete — stocked elsewhere | 0 at DigiKey; 30,000 TTI, 10,828 Newark, 2,169 Mouser | $0.032/100 at Newark | ECIA | — (rolled into a "resistor kit" row in July) |
| R6, R7: RC0603FR-07100KL | 100 kΩ, 1%, 0603 (×2) | Ready | 2,357,465 | $0.10 | DigiKey | — |
| R1: RC0603JR-071K8L | 1.8 kΩ, 5%, 0603 | Ready | 83,028 | $0.10 | DigiKey | — |
| R2, R3, R11, R13, R15–R18: RC0603JR-07470RL | 470 Ω, 5%, 0603 (×8) | Ready | 444,311 | $0.10 | DigiKey | — |
| R8–R10, R12, R14, R19, R20: RC0603JR-074K7L | 4.7 kΩ, 5%, 0603 (×7) | Ready | 1,151,400 | $0.10 | DigiKey | — |
| C1: GRM1885C1H222JA01D | 2.2 nF, 50 V, C0G, 0603 | Available (not at DigiKey) | 0 at DigiKey; 236,000 Avnet, 156,000 Future, 104,000 Newark | $0.10 | ECIA (4,000-pc price breaks) | — |
| C2: GRM188R61A106KE69D | 10 µF, 10 V, X5R, 0603 | Hard to obtain | 0 at all 4 distributors (19-wk lead) | $0.17 | DigiKey (back-order) | — |
| C3, C4, C5, C6, C7: GRM188R71H104KA93D | 100 nF, 50 V, X7R, 0603 (×5) | Obsolete, no stock | 0 (42-wk lead) | no current price | DigiKey (back-order) | — |
| S1: PUENTE | Printed solder-bridge net tie | No purchase required | — | — | — | — |
Connectors and Headers (00002A shield)
| Part | Spec/Package | Status | Stock | Price | Source | Drift |
|---|---|---|---|---|---|---|
| X1: MKDSN 1,5/ 4-5,08 | 4-pos, 5.08 mm pitch, 10 A / 300 V | Ready | 3,166 | $1.94 | DigiKey (cat. no. 1729144) | 144 → 3,166; price flat |
| X2, X3, X7: Molex 0022232021 | 2-pos, 2.54 mm friction lock (×3) | Ready | 87,682 | $0.18 | DigiKey | was "not checked" |
| X5, X6: Molex 0022232031 | 3-pos, 2.54 mm (×2) | Ready | 114,189 | $0.23 | DigiKey | was "not checked" |
| X4: Molex 0022232041 | 4-pos, 2.54 mm | Ready | 55,426 | $0.28 | DigiKey | was "not checked" |
| SV1–SV4: PRPC040SAAN-RC | 40-pin 0.1" breakaway strip | Ready | 48,820 | $1.23 | DigiKey | was "not checked" |
Active Devices — 0–30 V Analog Kit (supplied with Item 8)
| Part | Spec/Package | Status | Stock | Price | Source | Drift |
|---|---|---|---|---|---|---|
| U1–U3: TL081CP | JFET op-amp, 7–36 V supply, 8-DIP (×3) | Ready | 7,825 | $0.70 | DigiKey | 10,105 → 7,825; price flat |
| Q4: 2SD1047 | NPN 140 V / 12 A / 120 W, TO-3P-3 | Available again, thin stock | 174 | $6.56 | DigiKey (EVVO); ST's part still obsolete, 0 stock | was obsolete with zero stock — improved |
| Q2: 2SD882 | NPN 30 V / 3 A / 12.5 W, TO-126 | Ready | 8,003 | $2.50 | DigiKey | 8,181 → 8,003; price flat |
| Q1: SS9014 | NPN 45 V / 100 mA, TO-92 | Ready (as SS9014CBU) | 92,110 | $0.04 | DigiKey | was priced retail at $0.08; now an authorized-distributor part |
| Q3: SS9015 | PNP 45 V / 100 mA, TO-92 | Obsolete (all variants) — huge stock | 753,175 | $0.04 | DigiKey | was priced retail at $0.08; lifecycle now visible as obsolete |
| D1–D4: 1N5408 | 1000 V / 3 A, DO-201AA (×4) | Ready | 11,006 | $0.35 | DigiKey | 41,798 → 11,006; price flat |
| D11: 1N4004 | 400 V / 1 A, DO-41 | Ready | 199,396 | $0.14 | DigiKey | 128,112 → 199,396; price flat |
| D5, D6, D9, D10: 1N4148 | 100 V / 200 mA, DO-35 (×4) | Ready | 763,524 | $0.10 | DigiKey | 1 M+ → 1.49 M on the tape variant; price flat |
| D7, D8: 1N5231B | Zener 5.1 V, 500 mW, DO-35 (×2) | Ready | 78,528 | $0.18 | DigiKey | no baseline — July checked 1N4733A, a different part |
| D12: 5 mm red LED (WP7113ID) | T-1 3/4, Vf 1.9 V | Ready | 145,555 | $0.21 | DigiKey | was "not checked" |
Analog Kit Resistors and Trimmers (supplied with Item 8)
| Part | Spec/Package | Status | Stock | Price | Source | Drift |
|---|---|---|---|---|---|---|
| R7: SQP500JB-0R47 | 0.47 Ω, 5 W, ceramic axial | Ready | 535 | $1.26 | DigiKey | 605 → 535; price flat |
| R1: RSF100JB-73-2K2 | 2.2 kΩ, 1 W metal oxide axial | Ready | 6,693 | $0.20 | DigiKey | was "not checked" |
| R2–R6, R8–R22: 1/4 W 5% axial set | 33 Ω to 270 kΩ, axial 0207 | Ready (assortment) | in stock | $16.99 / 1,000 pc | Altex Electronics (Xpart 250 pc $8.21) | was a $9.95 RobotShop kit |
| RV1: 3296W-1-104LF | 100 kΩ multiturn trimmer, 9.53 × 4.83 mm | Ready | 11,823 | $2.73 | DigiKey | July priced a $2.38 Mouser listing; this is the Bourns part itself |
| P1, P2: 10 kΩ linear pot | Panel mount, 6.0 mm shaft (×2) | Ready — shaft not verified | in stock | $0.59 | ProtoSupplies; Taiwan Alpha RV110F-40-15A-B10K, Mouser 968 @ $2.27 | $0.95 → $0.59 |
Analog Kit Capacitors (supplied with Item 8)
| Part | Spec/Package | Status | Stock | Price | Source | Drift |
|---|---|---|---|---|---|---|
| C1: UVR1H332MHD | 3300 µF, 50 V, 18 mm dia, 7.5 mm pitch, 2.5 A ripple | Ready | 4,094 | $3.18 | DigiKey | was rolled into a $5.99 "electrolytic kit" |
| C2, C3: ECA-1HHG470 | 47 µF, 50 V, 6.3 mm dia (×2) | Ready | 39,883 Mouser; 12,688 DigiKey on the "I" variant | $0.44 | DigiKey / Mouser $0.42 | was rolled into a kit |
| C7: ECA-1HHG100 | 10 µF, 50 V, 5 mm dia | Ready | 10,612 on the "I" variant | $0.31 | DigiKey / Mouser $0.36 | was rolled into a kit |
| C4: C315C104K5R5TA | 0.1 µF, 50 V radial — 2.54 mm pitch (snapshot says 5.0 mm) | Ready | 7,195 | $0.62 | DigiKey | was rolled into a $14.95 kit |
| C5: C320C224K5R5TA | 0.22 µF, 50 V radial — 2.54 mm pitch (snapshot says 5.0 mm) | Ready | 1,157 | $1.56 | DigiKey; Mouser 5,973 @ $1.29 | was rolled into a kit |
| C6, C9: D101K20Y5PH63L2R | 100 pF, 100 V disc, 2.50 mm lead spacing (×2) | Hard to obtain | 0 at all 5 distributors (19-wk lead) | $0.04 at 20 k | DigiKey (back-order) | was rolled into a kit |
| C8: D331K20Y5PH63L2R | 330 pF, 100 V disc, 2.50 mm lead spacing | Hard to obtain | 0 at all 5 distributors (19-wk lead) | $0.04 at 20 k | DigiKey (back-order) | was rolled into a kit |
System, Chassis, Enclosure and Interconnect Hardware
| Part | Spec/Package | Status | Stock | Price | Source | Drift |
|---|---|---|---|---|---|---|
| Item 1: 2004 I2C LCD | 20×4 HD44780 + PCF8574, address 0x3F | Ready | in stock | $4.13 | BuyDisplay (eBay $8.25–$12.96) | $4.50 → $4.13 |
| Item 2: 10 kΩ panel pots (×2) | Panel mount, 8 mm hole | Ready | in stock | $0.59 | ProtoSupplies | $0.95 → $0.59 |
| Item 3a: EG2045-ND (red) | E-Switch PS1057ARED, SPST-NO, 12.60 × 11.30 mm cutout | Ready — single distributor | 979 | $1.92 | DigiKey | was "not checked" |
| Item 3b: EG2041-ND (black) | E-Switch PS1057ABLK, same cutout | Ready — single distributor | 7,640 | $1.83 | DigiKey | was "not checked" |
| Item 4: banana binding posts (×3) | 4 mm, ≥ 24 A, 9.5 mm panel hole | Ready — M5 stud not verified | in stock | $2.70 | Newark (Multicomp Pro 76-1502, 25 A) | was "not checked" |
| Item 5: Arduino Uno R3 | ATmega328P, 16 MHz, 5 V | Ready | in stock | $4.99 | Micro Center (CH340 board); genuine Uno Rev3 $30.95 PiShop | $4.99 unchanged |
| Item 6: DC barrel pigtail | 2.1 × 5.5 mm male to bare leads | Ready | in stock | $0.95 | Cable Leader | was "not checked" |
| Item 7: 3590S-2-103L (optional, ×2) | 10-turn 10 kΩ, 2 W, panel mount | Ready — expensive | 3,087 | $18.39 | DigiKey | was "not checked" |
| Item 8: Vkmaker 0–30 V PSU kit | 84 × 84 mm analog board kit | Ready | in stock | $9.99 | Banggood (AliExpress $4.25, eBay $16–$17) | was never priced |
| Item 9: DP-241-8-20 | 115/230 VAC to 20 VCT @ 5 A chassis transformer | Ready — price corrected | 50 DigiKey, 25 Mouser | $47.80 DigiKey / $46.10 Mouser | ECIA | July priced a generic 24 VAC unit at $25.67; the specified part is $46–$49 |
| Item 10: IEC C14 inlet + fuse | 250 VAC 10 A panel inlet, 5×20 mm fuse | Ready | in stock | $4.95 | Amplified Parts (switched+fused versions $5–$7) | was "not checked" |
| Item 11: EG4397-ND mains switch | E-Switch PB1973ABLKBLKEF0, SPST 15 A / 250 VAC, 19.20 × 13.00 mm cutout | Hard to obtain | 0 (15-wk lead, sole distributor) | $2.63 | DigiKey (back-order) | was "not checked" |
| Item 12: off-board pass transistor | See Q4 / Item 8 | Available, thin stock | 174 | $6.56 | DigiKey | see Q4 |
| Item 13a: heatsink | TO-247, 100 mm, ≤ 0.8 °C/W (not verified) | Ready — thin stock | 45 Mouser, 10 DigiKey | $7.60 | DigiKey (Wakefield 694-100) | $7.60 unchanged |
| Item 13b: ceramic insulator | TO-264 alumina, 22 × 28 × 0.6 mm (size not verified) | Ready | in stock | $3.60 | eBay (innovasupplies $16.43) | was "not checked" |
| Item 14: benchtop enclosure | ≥ 200 mm deep × 210 mm wide × 90 mm high | Not verified to spec | 1 DigiKey / 26 Mouser on the Hammond unit | $29.86 | Newark (Hammond 1455ZT2201 — 222 × 85.6 × 56 mm, too short) | $7.99 eBay box → nothing found that meets the envelope |
| Item A: 18 AWG silicone wire | Stranded, ≥ 300 V | Ready | in stock | $14.86 | Performance-PCs | was "not checked" |
| Item B: 24 AWG hookup wire | Stranded, tinned copper | Ready | in stock | $9.95 | Jameco | was "not checked" |
| Item C: laser-cut front panel | 3 mm two-colour acrylic, 203.2 × 85.76 mm | not checked | — | — | — | — |
| Item D: IEC C13 mains cord | NEMA 5-15P to C13, 18 AWG | Ready | in stock | $8.30 | Best Buy | was "not checked" |
| Item E: knobs (×4) | 6.0 mm and 6.35 mm shafts, pointer | Ready — shaft fit not verified | in stock | $3.13 | eBay | was "not checked" |
| Item F: PCB standoffs (8–12) | Self-adhesive nylon, 25 mm, 4.0 mm hole | Ready — 25 mm adhesive not verified | in stock | $3.90 | keszoox (screw-in 25 mm nylon at DigiKey $1.67) | was "not checked" |
| Item G: M3/M4/M5 fasteners | Stainless screws, washers, locknuts | Ready | in stock | $7.47 | Walmart (Hyper Tough 182-pc) | was "not checked" |
| Item H: L35-B2-5 ground lug | Copper mechanical lug, 8 str – 14 sol | Hard to obtain | 0 at all 5 distributors (3–12 wk leads) | $14.74 | DigiKey (back-order); base Blackburn L35 $3.29 retail | was "not checked" |
| Item I: dry-transfer lettering | White rub-on, ~3 mm | Ready | in stock | $7.99 | HobbyTown (Woodland Scenics) | was "not checked" |
| Item J: Faston terminals (6–10) | 3/16" (4.75 mm) female crimp | Ready | in stock | $5.98 | Parts Express (50 pc) | was "not checked" |
Substitutes
| For part | Substitute | Differences | Verified | Judgment |
|---|---|---|---|---|
| K1 G5LE-1-VDDC12 | G5LE-1 DC12 — $1.72, 6,012 at DigiKey, 9 distributors stocked | Same SPDT (1 Form C) contact form, 10 A contacts, 12 VDC coil. DigiKey's own "Parametric Equivalent" for the obsolete part | verified: contact form, contact rating, coil voltage (DigiKey parametric-equivalent entry vs the original's parametrics); not verified: pin layout, lead pitch, body dimensions | Recommended — check the pinout against the board before soldering |
| K1 G5LE-1-VDDC12 | G5LE-14 DC12 — $1.73, 24,375 | Every listed parameter identical to the original: through hole, 12 VDC coil, SPDT 1 Form C, 10 A, 33.3 mA coil, 9 VDC must-operate, AgSnO contacts, -25 to 85 °C | verified: mounting type, coil voltage, contact form, contact rating, coil current, contact material (DigiKey parametrics, both parts); not verified: pin layout and body dimensions | Recommended — best-evidenced option. Do not use G5LE-1A4 DC12 or G5LE-1A-E DC12: those are SPST-NO, the wrong contact form |
| R5 ERJ-3EKF1804V | CRCW06031M80FKEA — $0.10, 27,898 | 1.8 MΩ ±1% both; 1/8 W vs 1/10 W (exceeds — acceptable); TCR ±100 ppm/°C both | verified: package 0603 and body size on both (1.60 × 0.80 mm vs 1.55 × 0.85 mm, both standard 0603), resistance, tolerance, power (DigiKey parametrics) | Recommended |
| C2 GRM188R61A106KE69D | C1608X5R1A106K080AC — $0.27, 160,024 | None found: 10 µF, ±10%, 10 V, X5R on both | verified: package 0603 and body size 1.60 × 0.80 mm identical on both, plus value, tolerance, voltage, dielectric (DigiKey parametrics) | Recommended — drop-in |
| C3–C7 GRM188R71H104KA93D | C0603C104K5RACTU — $0.13, 7,158,308 | None found: 0.1 µF, ±10%, 50 V, X7R on both | verified: package 0603 and body size 1.60 × 0.80 mm identical on both, plus value, tolerance, voltage, dielectric (DigiKey parametrics) | Recommended — drop-in |
| C1 GRM1885C1H222JA01D | C0603C222J5GACTU — $0.40, 63,798 | None found: 2200 pF, ±5%, 50 V, C0G/NP0 on both. 4× the unit price, but buyable in ones | verified: package 0603 and body size 1.60 × 0.80 mm identical on both, plus value, tolerance, voltage, dielectric (DigiKey parametrics) | Recommended when you don't want a 4,000-piece reel |
| C6, C9 D101K20Y5PH63L2R | D101K20Y5PH63L6R — $0.43, 473 | Electrically identical (100 pF, 100 V, Y5P, 5.00 mm disc) but lead spacing 6.35 mm vs the original's 2.50 mm — the snapshot specifies a 2.5 mm pitch | verified: lead spacing on both from DigiKey parametrics — this is a mismatch, not a match | Rejected — footprint hard stop. The 2.5 mm-pitch siblings DigiKey suggests all show no stock |
| C8 D331K20Y5PH63L2R | D331K20Y5PH63L6R — $0.43, 28,162 | Same story: 330 pF, 100 V, Y5P, 5.00 mm disc, but lead spacing 6.35 mm vs 2.50 mm | verified: lead spacing on both from DigiKey parametrics — mismatch | Rejected — footprint hard stop |
| Q4 2SD1047 | TIP35CG — $3.65, 5,809 | TO-247-3 vs TO-3P-3; 25 A vs 12 A (exceeds); 125 W vs 120 W (exceeds); 100 V vs 140 V VCEO — short of the identity spec but within the snapshot's stated ≥ 100 V latitude, and the rail is only 30–34 V; hFE 15 at 15 A vs 35 at 5 A, so the driver must supply more base current | verified: package designation, collector current, power rating, VCEO from DigiKey parametrics on both; the snapshot explicitly permits TO-247. not verified: bolt-hole position and pin pitch (mounted off-board on flying leads, so this is a heatsink check) | Recommended as the fallback; the exact 2SD1047 is back in stock (174 pcs) if you prefer it |
| Q3 SS9015 | 2N3906 — $0.14, 25,866 | PNP TO-92 both; 200 mA vs 100 mA (exceeds); 625 mW vs 450 mW (exceeds); 40 V VCEO vs the snapshot's stated ≥ 45 V — falls short, though the snapshot itself names 2N3906 as acceptable | verified: package TO-92 (TO-226-3), collector current, power rating (DigiKey parametrics, both). not verified: pinout (E-B-C ordering), and the 45 V requirement is not met | Only if the obsolete SS9015 stock (753,175 pcs) runs out — check the node voltage and pinout first |
| Z1 824501361 | SMAJ36A — $0.48, 39,166 | 36 V standoff both; 40 V min breakdown vs 42.1 V typ; 58.1 V clamping and 400 W identical; DO-214AC (SMA) both | verified: package DO-214AC/SMA, standoff, breakdown, clamping and peak pulse power on both (DigiKey parametrics) — all meet the snapshot's spec. not verified: unidirectional vs bidirectional, which the snapshot requires | Acceptable on ratings; confirm polarity on the datasheet, for this part and for the Würth part DigiKey lists as SMAJ36CA |
| Item 11 EG4397-ND | Switched + fused IEC C14 inlet — $6.95 | Replaces Items 10 and 11 with one rear-panel part; listing states 10 A / 250 VAC, meeting the snapshot's "SPST ≥ 250 VAC, 5 A". Removes a front-panel hole | not verified — Google Shopping links resolve to redirects, not to a fetchable product page, so the mains rating comes from the listing title only | Plausible, unverified — confirm the rating and cutout on the seller's own page before ordering |
| Item 14 enclosure | Hammond 1455ZT2201 — $32.27, stock 1 | 222.00 × 85.60 × 55.98 mm against the required ≥ 200 mm depth / ≥ 210 mm width / ≥ 90 mm height — 34 mm too short | verified: body dimensions from DigiKey parametrics — they do not meet the requirement | Rejected on evidence. Select an enclosure manually against the envelope |
Verify any substitute against its datasheet before ordering.
Other dependencies
- Custom shield PCB "00002A" — 2 layers, 55.88 × 53.34 mm, 111 plated holes across 5 drill sizes, 8/8 mil track and space, solder mask both sides, top silkscreen; Gerbers in
00002A.zip. Not checked — no fabrication quote was obtained this run. The specifications are routine for any 2-layer prototype service. - Analog PCB (84 × 84 mm) — no separate fabrication needed; it comes with the Item 8 kit.
- Front panel —
frontPanel.svg, 203.2 × 85.76 mm, 3 mm two-colour acrylic (white on black), with an LCD window, 4 pot holes, 2 pushbutton holes, a power-switch hole and 3 binding-post holes. Not checked: the Ponoko material page the snapshot cites returned no extractable text when fetched this run, so neither availability nor price was confirmed. Note also that the mains switch specified as Item 11 needs a 19.20 × 13.00 mm rectangular cutout, larger than any hole in this cut list — reconcile the panel file with the switch you actually buy. - eBay / AliExpress listings cited in the snapshot (2004 LCD, Vkmaker kit, multiturn pot, enclosure, ceramic insulators, banana sockets) — not checked. A fetch of the Vkmaker listing was blocked by eBay, so these 2016–2017 listing IDs could not be confirmed alive. Every product they point at is currently purchasable from other sellers, priced above.
- DigiKey links cited in the snapshot (
EG2045-ND,EG2041-ND,EG4397-ND,595-1088-ND) — all four resolve to current catalogue parts; see the tables. - Calibration — RV1 must still be trimmed until the output reads 0.00 V at the minimum setting.
- Input constraint — 24 VAC AC-AC only. A DC power brick is forbidden by the design; this remains the easiest way to destroy the build.
Watch list
- R4 WSL3637R0100FEA — the whole Vishay WSL3637 10 mΩ family is out of stock across authorized distribution with 18–55 week leads and a High supply-chain risk rating. If it has not restocked by the next check, the shield needs a redesigned sense footprint.
- Item 11 EG4397-ND mains switch — zero stock, 15-week lead, and only one distributor lists it. A single-sourced mains part on a student-operated control is worth replacing pre-emptively.
- Item 3 pushbuttons (PS1057ARED / PS1057ABLK) — also single-sourced at DigiKey. Fine today (979 and 7,640 in stock), but there is no second source if that changes.
- C6, C8, C9 Vishay disc capacitors — zero stock everywhere, 20,000-piece minimum pricing, and the only in-stock siblings have the wrong lead spacing. Harmless while the Item 8 kit supplies them; a problem the day someone needs a replacement.
- Q3 SS9015 and Q1 SS9014 — obsolete lifecycle across every variant. Stock is enormous today (750 k+), so this is a multi-year horizon, not a next-check one.
- Item 9 DP-241-8-20 transformer — only 50 units at DigiKey and 25 at Mouser, at $46–$49. Low stock on the single most expensive line in the build.
- Item 14 enclosure — no in-evidence box meets the stated envelope; the next check should be run against a specific chosen enclosure rather than a generic search.