๐Ÿ›’ Phase-Gated Shopping List

Prototype on bench first โ†’ add portability later โ†’ add Nitinol at the end. Costs in RON (Romanian Leu), ~1 RON โ‰ˆ 0.20 EUR.

๐ŸŸก Phase 1 โ€” Prototype (Bench PSU)

Direct bench PSU โ†’ XT60 bus โ†’ MOSFET โ†’ muscle. No decoy, no buck converters, no ESP32 modules.

Already owned: ESP32, resistors (10kฮฉ, 220ฮฉ), breadboard, jumper wires, LEDs, buttons.

Electronics

ItemQtyEst. RONLink
IRLZ44N MOSFET (logic-level, N-channel, TO-220)ร—30~35๐Ÿ”— Link
XT60 Pre-Wired Pigtails (10 pairs, 10cm, 14AWG)ร—1~30๐Ÿ”— Link
Panel Fuse Holder 5ร—20mm (10-pack)ร—1~15๐Ÿ”— Link
Glass Fuse 5ร—20mm Assorted (100pcs, 0.5โ€“20A)ร—1~12๐Ÿ”— Link

Mechanical / Muscle

ItemQtyEst. RONLink
0.30mm Nylon Monofilament (100m roll, Nylon 6/6)ร—2~30๐Ÿ”— Link
AWG34 Nichrome NiCr 80/20 (25m roll, verify ฮฉ/m)ร—5~60๐Ÿ”— Link
PET Braided Sleeve 6mm ID (2m)ร—3~30๐Ÿ”— Link
PET Braided Sleeve 8mm ID (2m)ร—2~25๐Ÿ”— Link
Aluminum Oval Crimp Ferrules (M0.8โ€“M4 assortment)ร—1~20๐Ÿ”— Link
Heat Shrink Assortment (1โ€“6mm, black, 5m each)ร—2~25๐Ÿ”— Link

Gate Driver (Minimal โ€” Phase 1)

No 2N2222 needed. ESP32 GPIO โ†’ 220ฮฉ (owned) โ†’ MOSFET gate โ†’ 10kฮฉ pulldown (owned). MOSFET runs slightly warm but works for prototype.

CategoryEst.
Electronics~92 RON
Muscle + Mechanical~190 RON
Phase 1 TOTAL~282 RON

Bench PSU not included โ€” assumed already owned (30V/10A adjustable).

๐ŸŸ  Phase 2 โ€” Portable Power (PD3.1 USB-C)

Adds USB-C PD support. Depends on Phase 1 complete, elbow working, muscle behavior validated.

New Components

ItemQtyEst. RONLink
PD3.1 Type-C EPR 140W Decoy Moduleร—1~35๐Ÿ”— Link
LM2596 DC-DC Buck Converter (3A adjustable)ร—5~45๐Ÿ”— Link
Electrolytic Capacitor Kit (35V/50V, 630pcs)ร—1~55๐Ÿ”— Link
Ceramic Capacitor Kit (1206 SMD, 100pcs)ร—1~15๐Ÿ”— Link
IRLZ44N MOSFET (extra for shoulder)ร—20~25๐Ÿ”— Link
XT60 Pre-Wired Pigtailsร—1~30๐Ÿ”— Link
Velcro Cable Ties Kitร—1~15๐Ÿ”— Link
2N2222 NPN Transistor (100pcs)ร—1~8๐Ÿ”— Link

Full Gate Driver Circuit

ESP32 GPIO โ†’ 220ฮฉ (owned) โ†’ 2N2222 base | collector โ†’ 12V | emitter โ†’ MOSFET gate | 10kฮฉ pulldown (owned)

CategoryEst.
PD + Buck conversion~150 RON
Extra MOSFETs + connectors~55 RON
Wire management~15 RON
Gate drivers (2N2222)~8 RON
Phase 2 ADDITIONS~228 RON
Running total (P1+P2)~510 RON
๐ŸŸข Phase 3 โ€” Nitinol Precision (Fingers + Wrist)

Adds Flexinol/Nitinol SMA wire for fast precision movement. Depends on Phase 1+2 complete, arm functional.

ItemSpecQtyEst. RONSearch
Flexinol / Nitinol 0.1mmFingers (~180g pull)ร—2m~20Flexinol 0.1mm SMA wire
Flexinol / Nitinol 0.25mmWrist (~700g pull)ร—1m~15Flexinol 0.25mm SMA wire
Small Crimp Ferrules (M0.5โ€“M0.8 for Nitinol)โ€”ร—1~12๐Ÿ”— Link
CategoryEst.
Nitinol wire~35 RON
Small ferrules~12 RON
Phase 3 ADDITIONS~47 RON
Grand total (all phases)~557 RON

๐Ÿ“Š Summary Table

PhaseGoalEst. RONRunning Total
๐ŸŸก Phase 1Prototype on bench~282282 RON
๐ŸŸ  Phase 2Portable PD power~228510 RON
๐ŸŸข Phase 3Nitinol fingers/wrist~47~557 RON

โœ… Already Owned โ€” Do Not Buy

โš ๏ธ Critical Verification Notes

IRLZ44N: The "N" suffix is mandatory. IRLZ44 (without N) has Vgs(th) of 2โ€“4V โ€” may not fully turn on with 3.3V ESP32 GPIO. IRLZ44N is logic-level.
Nichrome resistance: 25m AWG34 โ‰ˆ 1500ฮฉ. At 12V โ†’ 8mA โ†’ 0.1W โ€” not enough heating. Target ~5โ€“10ฮฉ per fascicle. Use shorter lengths or multiple parallel strands. Verify ฮฉ/m with seller before bulk.
LM2596 potentiometer: Tiny and fragile on cheap modules โ€” add a dab of hot glue after setting voltage.

๐Ÿ”ง Not Included (Hardware / 3D Print)

๐Ÿ“„ Source: ๐Ÿฆพ Biomechanical Robotic Arm