docs(bom): add purchase column and markdown BOM with combo-kit sourcing

Adds Purchase column to bom.csv with verified sourcing links and a
companion BOM.md with grouped tables, combo-kit recommendations, and
critical pre-order notes.

Flagged during research:
- U1 package description was wrong (3.5x3.5mm); TPS61088 RHL is
  actually VQFN-20 4.5x3.5mm. KiCad footprint is correct, only the
  BOM description was off.
- PCB silkscreen shows TPS61088QRHLRQ1 (auto Q1) but the non-Q1
  TPS61088RHLR is a drop-in substitute with the same RHL pinout and
  is ~5x cheaper at LCSC.
- Pinout verified: schematic pins 1/3/4/5/6/7/8/9/11/12/15 match the
  TI datasheet RHL pinout.

Combo kits collapse R1-R5 (E96 sample book), C6/C8/C9 (0805 ceramic
kit), and C4/C5/C10/C11 (22uF 1206 50-pack) into single orders.

Constraint: ESP32 module excluded per user — sourced separately.
Constraint: L1 must handle >=10A; no-name AliExpress inductors avoided.
Directive: If swapping L1 to TDK SPM10065 from Bourns SRP1265, verify
KiCad footprint matches before ordering (10.5x10mm vs 12.6x12.6mm).
Confidence: high
Scope-risk: narrow
Not-tested: actual delivery/fitment of recommended AliExpress parts
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# Bill of Materials — firstpcb (Stepper Driver + 12V Boost)
> **Branch:** `feat/boost-converter-integration`
> **Generated:** 2026-05-23
> **Estimated cost:** ~$5080 first build (with combo kits) • ~$10/board in actually-used parts
---
## Critical Notes Before Ordering
| # | Issue | Impact |
|---|-------|--------|
| 1 | **BOM package field said "QFN-20 3.5×3.5mm"** for U1 | The actual TPS61088 RHL package is **VQFN-20, 4.5×3.5mm**. Your KiCad footprint is correct — only the BOM description was wrong (now fixed). |
| 2 | **PCB silkscreen reads `TPS61088QRHLRQ1`** (automotive Q1 variant), BOM lists `TPS61088RHLR` (commercial) | The commercial **TPS61088RHLR** is a fully drop-in substitute: same RHL package, same pinout. Use it — it's ~5× cheaper and far more available. |
| 3 | **U1 vs U2 designator mismatch** | Standalone `tps61088_boost.kicad_sch` test schematic uses U1; integrated `firstpcb.kicad_pcb` uses U2. Same part either way. |
| 4 | **TPS61088 pinout verified** | Schematic pins 1/3/4/5/6/7/8/9/11/12/15 = VIN/EN/SS-TR/COMP/FB/AGND/PGOOD/VOUT/BST/SW/PGND — matches TI datasheet exactly. ✅ |
| 5 | **L1 inductor substitution warning** | If swapping the Bourns SRP1265 for the cheaper TDK SPM10065, the footprint changes (12.6×12.6mm → 10.5×10mm). **Verify the KiCad footprint matches before ordering.** |
---
## Recommended Combo Kits (Buy These First)
These cover multiple BOM lines and stock you up for future builds:
| Kit | Covers | Est. Price | Source |
|-----|--------|-----------:|--------|
| **0805 E96 1% Resistor Sample Book** (170 values × 25pcs) | R1, R2, R3, R4, R5 + lifetime supply | ~$1525 | [Amazon B09Z2RDW2F](https://www.amazon.com/Resistor-ohm-10M-Assorted-Resistance-Resistor-0805/dp/B09Z2RDW2F) |
| **0805 SMD Ceramic Cap Kit** (50V, 22pF22µF) | C6, C8, C9 | ~$515 | [AliExpress multi-value kit](https://www.aliexpress.com/item/4000023618004.html) |
| **1206 22µF 25V X5R 50-pack** (CL31A226KAHNNNE) | C4, C5, C10, C11 | ~$8 | [AliExpress 50-pack](https://www.aliexpress.com/item/32751090379.html) |
| **JST-XH 2.54mm Connector Kit** (560pcs, 26 pin housings + crimps + headers) | StepperConnection1 | ~$812 | Search `JST-XH 2.54mm kit 560pcs` |
| **JST-EH 2.5mm 3-pin Kit** (housing + crimps + header) | SW1 | ~$46 | Search `JST-EH 2.5mm 3-pin housing crimp` |
> **Why the kit approach:** R3 (30.1K) and R4 (190K) are E96 values that aren't in basic E24 kits. Buying a proper E96 sample book is cheaper than ordering five individual reels and means you'll have every standard value for future projects.
---
## Single-Part Key Items
Parts that can't be combo'd — order these individually:
| Ref | Part | Source | Price | Notes |
|-----|------|--------|------:|-------|
| **U1** | TPS61088RHLR | [LCSC C87357](https://www.lcsc.com/product-detail/DC-DC-Converters_TI_TPS61088RHLR_TPS61088RHLR_C87357.html) | ~$0.61 | 14k in stock. Drop-in for the Q1 variant on the silkscreen. |
| **L1** | TDK SPM10065VT-2R2M-D (2.2µH, 16.6A) | [LCSC C1015860](https://www.lcsc.com/product-detail/Inductors-SMD_TDK-SPM10065VT-2R2M-D_C1015860.html) | ~$1.50 | Cheaper alternative to Bourns SRP1265. **Verify footprint match.** |
| **L1 (alt)** | Bourns SRP1265A-2R2M (2.2µH, 22A) | DigiKey | ~$23 | Matches original BOM footprint exactly. |
| **C3** | 100µF 25V SMD electrolytic, 6.3×5.8mm | AliExpress 10-pack | ~$23 | JAMICON/Lelon equivalents are fine. Verify pad layout. |
| **A4988** | Stepper driver module + heatsink, 5-pack | AliExpress | ~$58 | Any reputable seller. Heatsinks included. |
| **MotorPower1** | KF301-5.0-3P screw terminal, 10-pack | [AliExpress](https://www.aliexpress.com/item/32842003333.html) | ~$0.70 | Generic part. |
---
## Full BOM (with Purchase column)
### Active components
| Ref | Value | Pkg | Qty | Purchase | Notes |
|-----|-------|-----|----:|----------|-------|
| ESP32-WROOM1 | ESP32-C3-DevKitM-1 | Module | 1 | **SKIP** — user sources separately | Pinout-specific module from a special supplier. Do not order. |
| A4988 | A4988 Driver | Pololu breakout | 1 | AliExpress 5-pack (~$58) | Heatsink included. |
| U1 | TPS61088RHLR | VQFN-20 4.5×3.5mm (RHL) | 1 | [LCSC C87357](https://www.lcsc.com/product-detail/DC-DC-Converters_TI_TPS61088RHLR_TPS61088RHLR_C87357.html) (~$0.61) | Non-Q1 substitute for `TPS61088QRHLRQ1` on PCB. |
### Resistors — all covered by 0805 E96 sample book
| Ref | Value | Pkg | Qty | Purchase | Notes |
|-----|-------|-----|----:|----------|-------|
| R1 | 10K | 0805 1% | 1 | E96 kit | Pull-up / standard. |
| R2 | 10K | 0805 1% | 1 | E96 kit | |
| R5 | 10K | 0805 1% | 1 | E96 kit | |
| R3 | 30.1K | 0805 1% | 1 | E96 kit | Feedback divider — must be 1%. |
| R4 | 190K | 0805 1% | 1 | E96 kit | Feedback divider — must be 1%. |
### Capacitors — small values covered by 0805 ceramic kit
| Ref | Value | Pkg | Qty | Purchase | Notes |
|-----|-------|-----|----:|----------|-------|
| C8 | 47pF | 0805 C0G/NP0 50V | 1 | 0805 ceramic kit | C0G preferred, X7R OK at this value. |
| C9 | 100nF | 0805 X7R 50V | 1 | 0805 ceramic kit | Decoupling. |
| C6 | 22nF | 0805 X7R 50V | 1 | 0805 ceramic kit | TPS61088 compensation cap. |
### Capacitors — bulk (all covered by one 50-pack)
| Ref | Value | Pkg | Qty | Purchase | Notes |
|-----|-------|-----|----:|----------|-------|
| C4 | 22µF | 1206 X5R 25V | 1 | [AliExpress 50-pack](https://www.aliexpress.com/item/32751090379.html) (~$8) | CL31A226KAHNNNE ≡ GRM31CR61E226KE15L. **25V+ required** (12V output rail). |
| C5 | 22µF | 1206 X5R 25V | 1 | Same 50-pack | |
| C10 | 22µF | 1206 X5R 25V | 1 | Same 50-pack | |
| C11 | 22µF | 1206 X5R 25V | 1 | Same 50-pack | |
### Single-part caps & inductor
| Ref | Value | Pkg | Qty | Purchase | Notes |
|-----|-------|-----|----:|----------|-------|
| C3 | 100µF | SMD aluminum electrolytic, 6.3×5.8mm, 25V | 1 | AliExpress 10-pack (~$23) | Verify pad layout matches KiCad `CP_Elec_6.3x5.8` footprint. |
| L1 | 2.2µH | Shielded SMD power inductor | 1 | [LCSC TDK SPM10065VT-2R2M-D](https://www.lcsc.com/product-detail/Inductors-SMD_TDK-SPM10065VT-2R2M-D_C1015860.html) (~$1.50) **or** Bourns SRP1265A-2R2M (~$3) | **CRITICAL: must handle ≥10A.** Avoid no-name AliExpress inductors — saturation current often misrated. Footprint differs between TDK and Bourns. |
### Connectors & terminals
| Ref | Value | Pkg | Qty | Purchase | Notes |
|-----|-------|-----|----:|----------|-------|
| SW1 | B3B-EH-A | JST EH 3-pin THT, 2.5mm pitch | 1 | JST-EH 2.5mm 3-pin kit (~$46) | Get the kit — you need matching housings + crimps too. **EH series, not XH.** |
| MotorPower1 | KF301-5.0-3P | 3-pin screw terminal, 5mm pitch THT | 1 | [AliExpress 10-pack](https://www.aliexpress.com/item/32842003333.html) (~$0.70) | Generic; any KF301-5.0-3P works. |
| StepperConnection1 | B4B-XH-A | JST XH 4-pin THT, 2.54mm pitch | 1 | JST-XH 2.54mm kit (~$812) | Get the multi-pin kit; covers this build + future projects. |
---
## Sources
- [TPS61088 product page (TI)](https://www.ti.com/product/TPS61088/part-details/TPS61088RHLR)
- [LCSC TPS61088RHLR (C87357)](https://www.lcsc.com/product-detail/DC-DC-Converters_TI_TPS61088RHLR_TPS61088RHLR_C87357.html)
- [LCSC TDK SPM10065VT-2R2M-D (C1015860)](https://www.lcsc.com/product-detail/Inductors-SMD_TDK-SPM10065VT-2R2M-D_C1015860.html)
- [AliExpress 22µF 25V 1206 50-pack](https://www.aliexpress.com/item/32751090379.html)
- [AliExpress KF301-5.0-3P 10-pack](https://www.aliexpress.com/item/32842003333.html)
- [Amazon 170-value 0805 E96 1% resistor sample book](https://www.amazon.com/Resistor-ohm-10M-Assorted-Resistance-Resistor-0805/dp/B09Z2RDW2F)
- [Bourns SRP1265A-2R2M datasheet](https://bourns.com/products/magnetic-products/details/power-inductors-smd-high-current-shielded/srp1265a)
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Reference,Component,Value,Qty,Package,AliExpress Search/Link,AliExpress Price Est.,DigiKey Part Number,DigiKey Price Est.,Notes Reference,Component,Value,Qty,Package,AliExpress Search/Link,AliExpress Price Est.,DigiKey Part Number,DigiKey Price Est.,Purchase,Notes
ESP32-WROOM1,ESP32-WROOM-32 DevKit,ESP32-C3-DevKitM-1,1,Module,"ESP32 WROOM 32 development board 30 pin",~$4.00,N/A (use Adafruit/SparkFun),,Type-C versions slightly more ESP32-WROOM1,ESP32-WROOM-32 DevKit,ESP32-C3-DevKitM-1,1,Module,"ESP32 WROOM 32 development board 30 pin",~$4.00,N/A (use Adafruit/SparkFun),,SKIP - user sources separately,Pinout-specific module sourced from special supplier. Do not order.
A4988,A4988 Stepper Motor Driver,Pololu_Breakout_A4988,1,Module,"A4988 stepper motor driver module heatsink",~$2.00,Pololu #1182,~$5.95,Usually comes with heatsink. Packs of 5 ~$5 A4988,A4988 Stepper Motor Driver,Pololu_Breakout_A4988,1,Module,"A4988 stepper motor driver module heatsink",~$2.00,Pololu #1182,~$5.95,"AliExpress 5-pack: https://www.aliexpress.com/wholesale?SearchText=A4988+stepper+driver+5pcs (~$5-8 for 5pcs with heatsinks)",Get the 5-pack from any AliExpress seller; quality varies but functional. Heatsinks included.
U1,TPS61088 Boost Converter IC,TPS61088RHLR,1,QFN-20 3.5x3.5mm,"TPS61088RHLR QFN20",~$2.28/ea (3pcs min ~$6.84),296-40481-1-ND,~$3.89,LCSC C87357 ~$0.44/ea as alternative U1,TPS61088 Boost Converter IC,TPS61088RHLR,1,VQFN-20 4.5x3.5mm (RHL),"TPS61088RHLR QFN20",~$2.28/ea (3pcs min ~$6.84),296-40481-1-ND,~$3.89,"LCSC C87357: https://www.lcsc.com/product-detail/DC-DC-Converters_TI_TPS61088RHLR_TPS61088RHLR_C87357.html (~$0.61/ea, 14k in stock)",PACKAGE CORRECTION: TPS61088 RHL is 4.5x3.5mm not 3.5x3.5mm. PCB silkscreen says TPS61088QRHLRQ1 (auto Q1) but non-Q1 TPS61088RHLR is drop-in substitute with identical pinout - use the cheaper non-Q1. Pinout verified: pins 1/3/4/5/6/7/8/9/11/12/15 = VIN/EN/SS-TR/COMP/FB/AGND/PGOOD/VOUT/BST/SW/PGND.
R1,Resistor 0805 1%,10K,1,0805,"0805 resistor 10K 1%",~$1.50/100pcs,RC0805FR-0710KL,~$0.10, R1,Resistor 0805 1%,10K,1,0805,"0805 resistor 10K 1%",~$1.50/100pcs,RC0805FR-0710KL,~$0.10,"COMBO: 0805 E96 1% resistor sample book (170 values x 25pcs, ~$25 covers R1+R2+R3+R4+R5 and lifetime supply)",Use combo kit - see Notes section below.
R2,Resistor 0805 1%,10K,1,0805,"0805 resistor 10K 1%",~$1.50/100pcs,RC0805FR-0710KL,~$0.10, R2,Resistor 0805 1%,10K,1,0805,"0805 resistor 10K 1%",~$1.50/100pcs,RC0805FR-0710KL,~$0.10,COVERED BY RESISTOR KIT,Use the 0805 E96 sample book.
R5,Resistor 0805 1%,10K,1,0805,"0805 resistor 10K 1%",~$1.50/100pcs,RC0805FR-0710KL,~$0.10, R5,Resistor 0805 1%,10K,1,0805,"0805 resistor 10K 1%",~$1.50/100pcs,RC0805FR-0710KL,~$0.10,COVERED BY RESISTOR KIT,Use the 0805 E96 sample book.
R3,Resistor 0805 1% (feedback divider),30.1K,1,0805,"0805 resistor 30.1K 1% SMD",~$1.50/100pcs,RC0805FR-0730K1L,~$0.10,E96 value - not in basic kits. 1% required. R3,Resistor 0805 1% (feedback divider),30.1K,1,0805,"0805 resistor 30.1K 1% SMD",~$1.50/100pcs,RC0805FR-0730K1L,~$0.10,"COVERED BY 170-value E96 kit (30.1K is E96 standard value)",E96 standard - in any decent E96 kit like Amazon B09Z2RDW2F. If buying singles: LCSC.
R4,Resistor 0805 1% (feedback divider),190K,1,0805,"0805 resistor 190K 1% SMD",~$1.50/100pcs,RC0805FR-07190KL,~$0.10,E96 value - not in basic kits. 1% required. R4,Resistor 0805 1% (feedback divider),190K,1,0805,"0805 resistor 190K 1% SMD",~$1.50/100pcs,RC0805FR-07190KL,~$0.10,"COVERED BY 170-value E96 kit (190K is E96 standard value)",E96 standard - in any decent E96 kit. Critical to feedback divider - must be 1%.
C8,Capacitor 0805 C0G/NP0 50V,47pF,1,0805,"0805 47pF capacitor C0G",~$1.00/100pcs,Standard YAGEO/Samsung,~$0.10,C0G preferred for low-value caps C8,Capacitor 0805 C0G/NP0 50V,47pF,1,0805,"0805 47pF capacitor C0G",~$1.00/100pcs,Standard YAGEO/Samsung,~$0.10,"COMBO: 0805 SMD ceramic capacitor kit covering 22nF/47pF/100nF (e.g. AliExpress 0603/0805/1206 50V 22p-22uF kit, ~$5)",Use combo cap kit - C0G preferred but X7R acceptable at this value.
C9,Capacitor 0805 X7R 50V,100nF,1,0805,"0805 100nF 0.1uF capacitor",~$1.00/100pcs,Standard YAGEO/Samsung,~$0.10,Decoupling cap C9,Capacitor 0805 X7R 50V,100nF,1,0805,"0805 100nF 0.1uF capacitor",~$1.00/100pcs,Standard YAGEO/Samsung,~$0.10,COVERED BY CAPACITOR KIT,Universal decoupling value - included in every cap kit.
C6,Capacitor 0805 X7R 50V,22nF,1,0805,"0805 22nF capacitor X7R",~$1.00/100pcs,Standard YAGEO/Samsung,~$0.10,TPS61088 compensation cap C6,Capacitor 0805 X7R 50V,22nF,1,0805,"0805 22nF capacitor X7R",~$1.00/100pcs,Standard YAGEO/Samsung,~$0.10,COVERED BY CAPACITOR KIT,Compensation cap - tolerance not critical.
C4,Capacitor 1206 X5R 25V,22uF,1,1206,"1206 SMD capacitor 22uF 25V",~$2.50/100pcs,GRM31CR61E226KE15L,~$0.50,Must be 25V+ rated for 12V output C4,Capacitor 1206 X5R 25V,22uF,1,1206,"1206 SMD capacitor 22uF 25V",~$2.50/100pcs,GRM31CR61E226KE15L,~$0.50,"AliExpress 50-pack CL31A226KAHNNNE: https://www.aliexpress.com/item/32751090379.html (~$8/50pcs) - one order covers C4/C5/C10/C11",Samsung CL31A226KAHNNNE is direct equivalent to Murata GRM31CR61E226KE15L. Must be 25V+ (12V output bus).
C5,Capacitor 1206 X5R 25V,22uF,1,1206,"1206 SMD capacitor 22uF 25V",~$2.50/100pcs,GRM31CR61E226KE15L,~$0.50,Must be 25V+ rated for 12V output C5,Capacitor 1206 X5R 25V,22uF,1,1206,"1206 SMD capacitor 22uF 25V",~$2.50/100pcs,GRM31CR61E226KE15L,~$0.50,COVERED BY 50-PACK ABOVE,Same as C4 - one 50-pack covers all four positions.
C10,Capacitor 1206 X5R 25V,22uF,1,1206,"1206 SMD capacitor 22uF 25V",~$2.50/100pcs,GRM31CR61E226KE15L,~$0.50,Must be 25V+ rated for 12V output C10,Capacitor 1206 X5R 25V,22uF,1,1206,"1206 SMD capacitor 22uF 25V",~$2.50/100pcs,GRM31CR61E226KE15L,~$0.50,COVERED BY 50-PACK ABOVE,Same as C4.
C11,Capacitor 1206 X5R 25V,22uF,1,1206,"1206 SMD capacitor 22uF 25V",~$2.50/100pcs,GRM31CR61E226KE15L,~$0.50,Must be 25V+ rated for 12V output C11,Capacitor 1206 X5R 25V,22uF,1,1206,"1206 SMD capacitor 22uF 25V",~$2.50/100pcs,GRM31CR61E226KE15L,~$0.50,COVERED BY 50-PACK ABOVE,Same as C4.
C3,Capacitor SMD Electrolytic 25V,100uF,1,6.3x5.8mm,"100uF 25V SMD aluminum electrolytic capacitor 6.3mm",~$1.30/20pcs,Standard Nichicon/Panasonic,~$0.50,Verify pad matches KiCad footprint C3,Capacitor SMD Electrolytic 25V,100uF,1,6.3x5.8mm,"100uF 25V SMD aluminum electrolytic capacitor 6.3mm",~$1.30/20pcs,Standard Nichicon/Panasonic,~$0.50,"AliExpress 10-pack: search '100uF 25V SMD 6.3x5.8mm' (~$2-3 for 10pcs). LCSC: Lelon VEJ101M1EQRJ ~$0.15/ea",Verify pad layout matches KiCad footprint (CP_Elec_6.3x5.8). Cheaper SMD electrolytics from JAMICON/Lelon are fine.
L1,Power Inductor Shielded SMD,2.2uH,1,12.6x12.6mm,"SRP1265 2.2uH inductor",~$3.00,SRP1265A-2R2M (Bourns),~$2-3,Must handle >=10A. Critical for TPS61088. DigiKey safest source. L1,Power Inductor Shielded SMD,2.2uH,1,12.6x12.6mm,"SRP1265 2.2uH inductor",~$3.00,SRP1265A-2R2M (Bourns),~$2-3,"BEST: LCSC TDK SPM10065VT-2R2M-D C1015860 (10.5x10mm, 16.6A, ~$1.50). Alt: DigiKey Bourns SRP1265A-2R2M (12.6x12.6mm, 22A, ~$3)",CRITICAL - must handle >=10A continuous. TDK SPM10065 is smaller and cheaper than Bourns SRP1265 - verify your KiCad footprint matches the chosen part's pad pattern BEFORE ordering. Avoid no-name AliExpress inductors - saturation current is often misrated.
SW1,JST EH 3-pin Header,B3B-EH-A,1,Through-hole,"JST EH 3 pin connector 2.5mm header",~$1.00/10pcs,B3B-EH-A(LF)(SN),~$0.13,2.5mm pitch. Buy matching housings + crimp pins. SW1,JST EH 3-pin Header,B3B-EH-A,1,Through-hole,"JST EH 3 pin connector 2.5mm header",~$1.00/10pcs,B3B-EH-A(LF)(SN),~$0.13,"AliExpress JST-EH 2.5mm 3-pin kit with housing+crimps (50-set ~$4-6, search 'JST-EH 2.5mm 3-pin housing crimp')",Make sure to get matching female housings and crimp terminals - not just the PCB header. EH series specifically (NOT XH or PH).
MotorPower1,Screw Terminal 3-pin 5mm pitch,KF301-5.0-3P,1,Through-hole,"KF301 3 pin 5mm screw terminal PCB",~$0.50-1.00,Standard part,~$0.50-1.00,KF301-5.0-3P common Chinese equivalent MotorPower1,Screw Terminal 3-pin 5mm pitch,KF301-5.0-3P,1,Through-hole,"KF301 3 pin 5mm screw terminal PCB",~$0.50-1.00,Standard part,~$0.50-1.00,"AliExpress 10-pack: https://www.aliexpress.com/item/32842003333.html (~$0.70/10pcs)",Generic Chinese part - any KF301-5.0-3P seller works.
StepperConnection1,JST XH 4-pin Header,B4B-XH-A,1,Through-hole,"JST XH 4 pin 2.54mm connector header",~$1.00/20pcs,B4B-XH-A(LF)(SN),~$0.15,2.54mm pitch. Buy matching housings + crimp pins. StepperConnection1,JST XH 4-pin Header,B4B-XH-A,1,Through-hole,"JST XH 4 pin 2.54mm connector header",~$1.00/20pcs,B4B-XH-A(LF)(SN),~$0.15,"COMBO: AliExpress JST-XH 2.54mm full kit (560pcs 2/3/4/5/6-pin housing+crimps+headers, ~$8-12) - massive overkill but covers all future projects",Search 'JST-XH 2.54mm connector kit 560pcs'. Brand names: Taiss, GTIWUNG, HALJIA all sell equivalent kits.
,,,,,,,,,,
SUMMARY,,,,,,,,,,
,,,,,,,,,,
COMBO PACK RECOMMENDATIONS:,,,,,,,,,,
"1. 0805 E96 1% Resistor Sample Book (170 values x 25pcs)",,,,,,,,,~$15-25,Covers R1/R2/R3/R4/R5 + every future project. Must be E96 (1%) to include 30.1K and 190K.
"2. 0805 SMD Ceramic Capacitor Kit (50V, 22pF-22uF range)",,,,,,,,,~$5-15,Covers C6/C8/C9 (22nF/47pF/100nF). Make sure kit includes those specific values.
"3. 1206 22uF 25V X5R 50-pack",,,,,,,,,~$8,Covers C4/C5/C10/C11.
"4. JST-XH 2.54mm Connector Kit (multi-pin)",,,,,,,,,~$8-12,Covers StepperConnection1 (4-pin) + future projects.
"5. JST-EH 2.5mm 3-pin Kit (housing+crimps+header)",,,,,,,,,~$4-6,Covers SW1. Make sure it's EH series specifically.
,,,,,,,,,,
SINGLE-PART KEY ITEMS:,,,,,,,,,,
"U1 TPS61088RHLR - LCSC C87357",,,,,,,,,~$0.61,The non-Q1 variant is drop-in substitute for TPS61088QRHLRQ1 on PCB silkscreen. Same RHL package same pinout.
"L1 TDK SPM10065VT-2R2M-D - LCSC C1015860",,,,,,,,,~$1.50,VERIFY footprint match before ordering - SPM10065 (10.5x10mm) vs original Bourns SRP1265 (12.6x12.6mm).
"C3 100uF 25V SMD electrolytic - any 6.3x5.8mm 10-pack",,,,,,,,,~$2-3,Verify pad layout matches your KiCad footprint.
"A4988 5-pack with heatsinks - AliExpress",,,,,,,,,~$5-8,Generic functional drivers.
"KF301-5.0-3P 10-pack - AliExpress",,,,,,,,,~$0.70,Generic part.
,,,,,,,,,,
TOTAL ESTIMATED COST:,,,,,,,,,~$50-80,One-time setup with combo kits. ~$10 in actually-used parts per board. ESP32 module sourced separately by user.
1 Reference Component Value Qty Package AliExpress Search/Link AliExpress Price Est. DigiKey Part Number DigiKey Price Est. Purchase Notes
2 ESP32-WROOM1 ESP32-WROOM-32 DevKit ESP32-C3-DevKitM-1 1 Module ESP32 WROOM 32 development board 30 pin ~$4.00 N/A (use Adafruit/SparkFun) SKIP - user sources separately Type-C versions slightly more Pinout-specific module sourced from special supplier. Do not order.
3 A4988 A4988 Stepper Motor Driver Pololu_Breakout_A4988 1 Module A4988 stepper motor driver module heatsink ~$2.00 Pololu #1182 ~$5.95 AliExpress 5-pack: https://www.aliexpress.com/wholesale?SearchText=A4988+stepper+driver+5pcs (~$5-8 for 5pcs with heatsinks) Usually comes with heatsink. Packs of 5 ~$5 Get the 5-pack from any AliExpress seller; quality varies but functional. Heatsinks included.
4 U1 TPS61088 Boost Converter IC TPS61088RHLR 1 QFN-20 3.5x3.5mm VQFN-20 4.5x3.5mm (RHL) TPS61088RHLR QFN20 ~$2.28/ea (3pcs min ~$6.84) 296-40481-1-ND ~$3.89 LCSC C87357: https://www.lcsc.com/product-detail/DC-DC-Converters_TI_TPS61088RHLR_TPS61088RHLR_C87357.html (~$0.61/ea, 14k in stock) LCSC C87357 ~$0.44/ea as alternative PACKAGE CORRECTION: TPS61088 RHL is 4.5x3.5mm not 3.5x3.5mm. PCB silkscreen says TPS61088QRHLRQ1 (auto Q1) but non-Q1 TPS61088RHLR is drop-in substitute with identical pinout - use the cheaper non-Q1. Pinout verified: pins 1/3/4/5/6/7/8/9/11/12/15 = VIN/EN/SS-TR/COMP/FB/AGND/PGOOD/VOUT/BST/SW/PGND.
5 R1 Resistor 0805 1% 10K 1 0805 0805 resistor 10K 1% ~$1.50/100pcs RC0805FR-0710KL ~$0.10 COMBO: 0805 E96 1% resistor sample book (170 values x 25pcs, ~$25 covers R1+R2+R3+R4+R5 and lifetime supply) Use combo kit - see Notes section below.
6 R2 Resistor 0805 1% 10K 1 0805 0805 resistor 10K 1% ~$1.50/100pcs RC0805FR-0710KL ~$0.10 COVERED BY RESISTOR KIT Use the 0805 E96 sample book.
7 R5 Resistor 0805 1% 10K 1 0805 0805 resistor 10K 1% ~$1.50/100pcs RC0805FR-0710KL ~$0.10 COVERED BY RESISTOR KIT Use the 0805 E96 sample book.
8 R3 Resistor 0805 1% (feedback divider) 30.1K 1 0805 0805 resistor 30.1K 1% SMD ~$1.50/100pcs RC0805FR-0730K1L ~$0.10 COVERED BY 170-value E96 kit (30.1K is E96 standard value) E96 value - not in basic kits. 1% required. E96 standard - in any decent E96 kit like Amazon B09Z2RDW2F. If buying singles: LCSC.
9 R4 Resistor 0805 1% (feedback divider) 190K 1 0805 0805 resistor 190K 1% SMD ~$1.50/100pcs RC0805FR-07190KL ~$0.10 COVERED BY 170-value E96 kit (190K is E96 standard value) E96 value - not in basic kits. 1% required. E96 standard - in any decent E96 kit. Critical to feedback divider - must be 1%.
10 C8 Capacitor 0805 C0G/NP0 50V 47pF 1 0805 0805 47pF capacitor C0G ~$1.00/100pcs Standard YAGEO/Samsung ~$0.10 COMBO: 0805 SMD ceramic capacitor kit covering 22nF/47pF/100nF (e.g. AliExpress 0603/0805/1206 50V 22p-22uF kit, ~$5) C0G preferred for low-value caps Use combo cap kit - C0G preferred but X7R acceptable at this value.
11 C9 Capacitor 0805 X7R 50V 100nF 1 0805 0805 100nF 0.1uF capacitor ~$1.00/100pcs Standard YAGEO/Samsung ~$0.10 COVERED BY CAPACITOR KIT Decoupling cap Universal decoupling value - included in every cap kit.
12 C6 Capacitor 0805 X7R 50V 22nF 1 0805 0805 22nF capacitor X7R ~$1.00/100pcs Standard YAGEO/Samsung ~$0.10 COVERED BY CAPACITOR KIT TPS61088 compensation cap Compensation cap - tolerance not critical.
13 C4 Capacitor 1206 X5R 25V 22uF 1 1206 1206 SMD capacitor 22uF 25V ~$2.50/100pcs GRM31CR61E226KE15L ~$0.50 AliExpress 50-pack CL31A226KAHNNNE: https://www.aliexpress.com/item/32751090379.html (~$8/50pcs) - one order covers C4/C5/C10/C11 Must be 25V+ rated for 12V output Samsung CL31A226KAHNNNE is direct equivalent to Murata GRM31CR61E226KE15L. Must be 25V+ (12V output bus).
14 C5 Capacitor 1206 X5R 25V 22uF 1 1206 1206 SMD capacitor 22uF 25V ~$2.50/100pcs GRM31CR61E226KE15L ~$0.50 COVERED BY 50-PACK ABOVE Must be 25V+ rated for 12V output Same as C4 - one 50-pack covers all four positions.
15 C10 Capacitor 1206 X5R 25V 22uF 1 1206 1206 SMD capacitor 22uF 25V ~$2.50/100pcs GRM31CR61E226KE15L ~$0.50 COVERED BY 50-PACK ABOVE Must be 25V+ rated for 12V output Same as C4.
16 C11 Capacitor 1206 X5R 25V 22uF 1 1206 1206 SMD capacitor 22uF 25V ~$2.50/100pcs GRM31CR61E226KE15L ~$0.50 COVERED BY 50-PACK ABOVE Must be 25V+ rated for 12V output Same as C4.
17 C3 Capacitor SMD Electrolytic 25V 100uF 1 6.3x5.8mm 100uF 25V SMD aluminum electrolytic capacitor 6.3mm ~$1.30/20pcs Standard Nichicon/Panasonic ~$0.50 AliExpress 10-pack: search '100uF 25V SMD 6.3x5.8mm' (~$2-3 for 10pcs). LCSC: Lelon VEJ101M1EQRJ ~$0.15/ea Verify pad matches KiCad footprint Verify pad layout matches KiCad footprint (CP_Elec_6.3x5.8). Cheaper SMD electrolytics from JAMICON/Lelon are fine.
18 L1 Power Inductor Shielded SMD 2.2uH 1 12.6x12.6mm SRP1265 2.2uH inductor ~$3.00 SRP1265A-2R2M (Bourns) ~$2-3 BEST: LCSC TDK SPM10065VT-2R2M-D C1015860 (10.5x10mm, 16.6A, ~$1.50). Alt: DigiKey Bourns SRP1265A-2R2M (12.6x12.6mm, 22A, ~$3) Must handle >=10A. Critical for TPS61088. DigiKey safest source. CRITICAL - must handle >=10A continuous. TDK SPM10065 is smaller and cheaper than Bourns SRP1265 - verify your KiCad footprint matches the chosen part's pad pattern BEFORE ordering. Avoid no-name AliExpress inductors - saturation current is often misrated.
19 SW1 JST EH 3-pin Header B3B-EH-A 1 Through-hole JST EH 3 pin connector 2.5mm header ~$1.00/10pcs B3B-EH-A(LF)(SN) ~$0.13 AliExpress JST-EH 2.5mm 3-pin kit with housing+crimps (50-set ~$4-6, search 'JST-EH 2.5mm 3-pin housing crimp') 2.5mm pitch. Buy matching housings + crimp pins. Make sure to get matching female housings and crimp terminals - not just the PCB header. EH series specifically (NOT XH or PH).
20 MotorPower1 Screw Terminal 3-pin 5mm pitch KF301-5.0-3P 1 Through-hole KF301 3 pin 5mm screw terminal PCB ~$0.50-1.00 Standard part ~$0.50-1.00 AliExpress 10-pack: https://www.aliexpress.com/item/32842003333.html (~$0.70/10pcs) KF301-5.0-3P common Chinese equivalent Generic Chinese part - any KF301-5.0-3P seller works.
21 StepperConnection1 JST XH 4-pin Header B4B-XH-A 1 Through-hole JST XH 4 pin 2.54mm connector header ~$1.00/20pcs B4B-XH-A(LF)(SN) ~$0.15 COMBO: AliExpress JST-XH 2.54mm full kit (560pcs 2/3/4/5/6-pin housing+crimps+headers, ~$8-12) - massive overkill but covers all future projects 2.54mm pitch. Buy matching housings + crimp pins. Search 'JST-XH 2.54mm connector kit 560pcs'. Brand names: Taiss
22
23 SUMMARY
24
25 COMBO PACK RECOMMENDATIONS:
26 1. 0805 E96 1% Resistor Sample Book (170 values x 25pcs) ~$15-25 Covers R1/R2/R3/R4/R5 + every future project. Must be E96 (1%) to include 30.1K and 190K.
27 2. 0805 SMD Ceramic Capacitor Kit (50V, 22pF-22uF range) ~$5-15 Covers C6/C8/C9 (22nF/47pF/100nF). Make sure kit includes those specific values.
28 3. 1206 22uF 25V X5R 50-pack ~$8 Covers C4/C5/C10/C11.
29 4. JST-XH 2.54mm Connector Kit (multi-pin) ~$8-12 Covers StepperConnection1 (4-pin) + future projects.
30 5. JST-EH 2.5mm 3-pin Kit (housing+crimps+header) ~$4-6 Covers SW1. Make sure it's EH series specifically.
31
32 SINGLE-PART KEY ITEMS:
33 U1 TPS61088RHLR - LCSC C87357 ~$0.61 The non-Q1 variant is drop-in substitute for TPS61088QRHLRQ1 on PCB silkscreen. Same RHL package same pinout.
34 L1 TDK SPM10065VT-2R2M-D - LCSC C1015860 ~$1.50 VERIFY footprint match before ordering - SPM10065 (10.5x10mm) vs original Bourns SRP1265 (12.6x12.6mm).
35 C3 100uF 25V SMD electrolytic - any 6.3x5.8mm 10-pack ~$2-3 Verify pad layout matches your KiCad footprint.
36 A4988 5-pack with heatsinks - AliExpress ~$5-8 Generic functional drivers.
37 KF301-5.0-3P 10-pack - AliExpress ~$0.70 Generic part.
38
39 TOTAL ESTIMATED COST: ~$50-80 One-time setup with combo kits. ~$10 in actually-used parts per board. ESP32 module sourced separately by user.