brewery-pid-bom
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# Brewery PID Controller — Per-Unit PCB BOM
**Project:** Brewery PID Replacement
**Revision:** 1.0
**Date:** 2026-04-16
**Designer:** Topher
**Status:** Design checklist
---
## Main Components
| Qty | Component | Package | Notes |
|-----|-----------|---------|-------|
| 1 | ESP32-S3 Supermini (AITRIP) | DIP-40 | Amazon B0D47HBFDY, 5-pack ~$13 |
| 1 | MAX31865 breakout board | PCB w/ headers | Amazon B0GSYV2SM8, 5-pack $19 |
| 1 | G3MB-202P SSR | DIP-4 | 2A, 120-380V AC output |
| 1 | MOV (250V, 10mm) | Radial | Spike protection across SSR output |
| 1 | 220Ω resistor | 0805 or 1/4W | SSR LED input current limit |
| 2 | 3-position terminal block | 5.08mm pitch | PT100 input, 120V output |
| 1 | 2-position terminal block | 5.08mm pitch | 120V AC input |
---
## Passives
| Qty | Component | Package | Notes |
|-----|-----------|---------|-------|
| 3 | 100nF ceramic cap | 0805 | VCC decoupling (ESP32, MAX31865, near SSR) |
| 2 | 10nF ceramic cap | 0805 | MAX31865 input filtering |
| 1 | 49.9KΩ resistor (0.1%) | 0805 | MAX31865 reference (or use module's built-in) |
| 1 | 10KΩ resistor | 0805 | Pull-up/down if needed |
| 1 | SMB5819 diode | DO-214AA | Reverse polarity protection on 5V input |
| 1 | SMBJ5.0A TVS | DO-214AA | 5V rail overvoltage clamping |
---
## Power Supply
| Qty | Component | Package | Notes |
|-----|-----------|---------|-------|
| 1 | 5V regulator (AMS1117-5.0 or similar) | SOT-223 | If not using bus from existing supply |
| 2 | 10µF tantalum cap | Case A | Input/output bulk caps |
| 1 | Power indicator LED | 0805 or 3mm | +5V present |
| 1 | 470Ω resistor | 0805 | LED current limit |
---
## Mechanical / Board
| Qty | Component | Notes |
|-----|-----------|-------|
| 1 | Custom PCB | JLCPCB, 2oz Cu, ENIG finish |
| 1 | ESP32-S3 socket (optional) | DIP-40 socket if hot-swappable desired |
| 4 | M3 standoff | Board mounting |
| 4 | M3 screw | |
---
## Signal Connections
### ESP32-S3 → MAX31865
| ESP32 Pin | MAX31865 Signal |
|-----------|-----------------|
| GPIO (SPI CLK) | SCK |
| GPIO (SPI MISO) | SDO |
| GPIO (SPI MOSI) | SDI |
| GPIO (CS) | CS |
### ESP32-S3 → G3MB-202P
| ESP32 Pin | G3MB-202P |
|-----------|-----------|
| GPIO (output) | Input+ (through 220Ω) |
| GND | Input- |
### Power
| Rail | Connection |
|------|------------|
| +5V | AMS1117 input, MAX31865 VCC, ESP32 VUSB |
| +3.3V | ESP32 VCC (from board regulator) |
| GND | Common ground |
---
## Checkpoints
- [ ] PT100 3-wire connection wired correctly (A, B, Rdout)
- [ ] 220Ω resistor on SSR input (not optional — sets LED current)
- [ ] MOV across SSR output terminals (polarity doesn't matter for AC)
- [ ] TVS on +5V rail (方向)
- [ ] Decoupling caps physically close to IC VCC pins
- [ ] 49.9K reference resistor on MAX31865 (if module doesn't have it)
- [ ] Reverse polarity diode on power input (stripe = cathode = +5V side)
- [ ] Thermal calculation: G3MB-202P needs heatsink if ambient >40°C
- [ ] Ground plane on PCB for noise immunity
- [ ] Screw terminal torque specs (PT100 wire gauge)
---
## Not Included (handled elsewhere)
- Nextion display (separate unit, UART connection)
- 120V AC wiring to contactors (existing)
- Enclosure (TBD per install location)
- PT100 sensor (existing in vessels)
---
## References
- G3MB-202P datasheet: Omron G3MB Solid State Relay
- MAX31865: MAX31865 datasheet (3-wire PT100 interface)
- ESP32-S3 Supermini: Amazon product page / pinout diagram
- TPS3823 watchdog: Optional, not included in BOM (see project notes)
Notes