📡 EMF METER 📡

MODULAR TERMINAL BLOCKS

2-Position Pluggable Blocks - Ultimate Flexibility!

⚠️ THIS VERSION USES 2-POSITION MODULAR TERMINAL BLOCKS ⚠️
MOUNT TERMINALS EXACTLY WHERE YOU NEED THEM
SHORTER WIRES = CLEANER BUILD!

💡 LID-MOUNTED DESIGN - CLEAN PROFESSIONAL LOOK 💡
MOUNTS IN LID (user-facing panel): 5× LEDs, OLED display, TP4056 USB-C charge port
HALL SENSOR: Mounts INSIDE lid (no hole needed - detects through plastic!)
STAYS IN BASE (heavy/internal): Battery, ESP32, terminal blocks
USB EXTENSION: 3-4" Micro-USB extension plugs into ESP32 (stays inside) for easy firmware updates
WIRE LENGTHS: Use 6-8" wires from base to lid components so you can open and work on it!

🔲 INSIDE BOX VIEW (100mm × 60mm × 25mm)

╔══════════════════════════════════════════════════════════╗ ║ LID (TOP PANEL - USER-FACING) - CLEAN DESIGN: ║ ╟──────────────────────────────────────────────────────────╢ ║ ║ ║ ┌─────────────────────────────────────────┐ ║ ║ │ [OLED DISPLAY] │ ║ ║ │ (rectangle cutout) │ ║ ║ └─────────────────────────────────────────┘ ║ ║ ║ ║ ○ ○ ○ ○ ○ [USB-C] ║ ║ CLEAR BLUE GREEN YELLOW RED TP4056 ║ ║ LED1 LED2 LED3 LED4 LED5 CHARGE ║ ║ (5mm holes for each) (8mm hole) ║ ║ ║ ║ [HALL SENSOR] ← Inside lid, front edge (NO HOLE!) ║ ║ Detects through plastic - clean professional look ║ ║ ║ ║ 6-8" wires run down to base components ↓ ║ ╚══════════════════════════════════════════════════════════╝ ┌──────────────────────────────────────────────────────────┐ │ BASE (BOTTOM) - COMPONENTS STAY PUT: │ ├──────────────────────────────────────────────────────────┤ │ │ │ ┌─────────┐ ┌──────────┐ [TB-PWR] │ │ │ Battery │ │ ESP32 │ (2-pos) │ │ │ Holder │ │ Board │ │ │ │ 18650 │ │ + USB │ [TB-GND] │ │ └─────────┘ │Extension │ (2-pos) │ │ └──────────┘ │ │ │ │ [TB-LED1] [TB-LED2] [TB-LED3] ← Terminal blocks │ │ (2-pos) (2-pos) (2-pos) for LED grounds │ │ │ │ Micro-USB extension cable tucked along side ~~~ │ │ (for firmware updates - plug laptop into male end) │ │ │ └──────────────────────────────────────────────────────────┘ KEY: - LID HOLES: 5× LEDs (5mm), 1× OLED (rectangle), 1× USB-C (8mm) - THAT'S IT! - Hall sensor INSIDE lid (magnetic fields pass through plastic) - LID components use 6-8" wires to reach base terminals - Battery stays in base (heaviest component = stability) - ESP32 stays in base (brain, easy GPIO access) - USB extension plugs into ESP32, male end tucks near edge - TP4056 charge port accessible from outside (no opening needed) - Terminal blocks in base for all power/ground distribution - CLEAN PROFESSIONAL LOOK: No ugly sensors sticking out!

📋

What You Need

📦 Complete shopping list with Amazon links:
→ Click here for full shopping list ←

5-6× 2-position screw terminal blocks (5.08mm pitch)
ESP32 board
OLED display (0.96" I2C)
Hall sensor module (A3144)
5× LEDs (1 clear, 1 blue, 1 green, 1 yellow, 1 red - perfect progression!)
5× 220Ω resistors
3× 0.1µF ceramic capacitors (REQUIRED for stable power)
Solid core wire (22 AWG) in multiple colors - 6-8" lengths for lid components
Micro-USB extension cable (3-4", male-to-female) for ESP32 firmware updates
Wire strippers
Small flathead screwdriver
18650 battery + holder
USB-C charging module (TP4056) - mounts in lid
Slide switch (SPDT)
Project box (100×60×25mm) - pre-drilled for kits!
Foam tape or hot glue

📍

Terminal Block Assignments

🔋 POWER AREA (Near Battery):

Terminal Block "TB-PWR" (2-position): ├─ Position 1: ESP32 3.3V pin (RED wire) ├─ Position 2: OLED VCC (RED wire) └─ [Hall sensor VCC can share Position 2] Terminal Block "TB-GND" (2-position): ├─ Position 1: ESP32 GND pin (BLACK wire) ├─ Position 2: OLED GND (BLACK wire) └─ [Hall sensor GND can share Position 2] Mount these blocks near battery holder with foam tape!

💡 LED AREA (Near Front Panel):

Terminal Block "TB-LED1" (2-position): ├─ Position 1: LED #1 resistor → GND └─ Position 2: LED #2 resistor → GND Terminal Block "TB-LED2" (2-position): ├─ Position 1: LED #3 resistor → GND └─ Position 2: LED #4 resistor → GND Terminal Block "TB-LED3" (2-position): ├─ Position 1: LED #5 resistor → GND └─ Position 2: [Spare] Mount these blocks near front panel where LEDs poke through! Connect all to TB-GND with single BLACK wire.

Mount All Components First

Stick battery holder to LEFT side of box bottom (foam tape)
Stick ESP32 to MIDDLE of box bottom (foam tape)
Stick TB-PWR terminal block near battery (foam tape)
Stick TB-GND terminal block near battery (foam tape)
Stick TB-LED1, TB-LED2, TB-LED3 near front panel area (foam tape)
Make sure ESP32 USB port is accessible!

💡 Pro Tip: Mount everything BEFORE wiring!
This lets you measure exact wire lengths needed - no excess wire mess!

Power Distribution

TB-PWR (Power Bus):

ESP32: 3.3V pin ───> RED WIRE (2-3 inches) ───> TB-PWR Position 1

OLED: VCC pin ───> RED WIRE (3-4 inches) ───> TB-PWR Position 2

Hall Sensor: VCC pin ───> RED WIRE (3-4 inches) ───> TB-PWR Position 2 (shared with OLED)

TB-GND (Ground Bus):

ESP32: GND pin ───> BLACK WIRE (2-3 inches) ───> TB-GND Position 1

OLED: GND pin ───> BLACK WIRE (3-4 inches) ───> TB-GND Position 2

Hall Sensor: GND pin ───> BLACK WIRE (3-4 inches) ───> TB-GND Position 2 (shared with OLED)

Direct ESP32 Connections (No Terminals)

These go DIRECTLY from component to ESP32 GPIO pins:
NO terminal blocks needed - just point-to-point wiring!

OLED Display I2C:

OLED: SDA ───> BLUE WIRE ───> ESP32: GPIO 21

OLED: SCL ───> YELLOW WIRE ───> ESP32: GPIO 22

Hall Sensor Signal:

Hall Sensor: OUT ───> GREEN WIRE ───> ESP32: GPIO 34

LED Wiring

💡 PRO TIP: LID MOUNTING 💡
Mount LEDs and OLED to the LID for clean front panel appearance!
Use 6-8" wire lengths so you can open lid and still work on device.
Components stay in BASE (ESP32, battery, terminals), display/LEDs in LID.

⚠️ LED POLARITY! ⚠️
LONG LEG (+) → ESP32 GPIO pin
SHORT LEG (-) → 220Ω resistor → Terminal block → TB-GND

LED COLOR PROGRESSION:
Level 1: CLEAR (base/on) → Level 2: BLUE → Level 3: GREEN → Level 4: YELLOW → Level 5: RED (max)

LED #1 - CLEAR (Level 1 - Base/On):

ESP32: GPIO 13 → WHITE (6-8" for lid mounting) → LED LONG leg → LED SHORT leg → 220Ω → TB-LED1 Pos 1

LED #2 - BLUE (Level 2):

ESP32: GPIO 12 → BLUE (6-8" for lid mounting) → LED LONG leg → LED SHORT leg → 220Ω → TB-LED1 Pos 2

LED #3 - GREEN (Level 3):

ESP32: GPIO 14 → GREEN (6-8" for lid mounting) → LED LONG leg → LED SHORT leg → 220Ω → TB-LED2 Pos 1

LED #4 - YELLOW (Level 4):

ESP32: GPIO 27 → ORANGE (6-8" for lid mounting) → LED LONG leg → LED SHORT leg → 220Ω → TB-LED2 Pos 2

LED #5 - RED (Level 5 - MAX):

ESP32: GPIO 26 → RED (6-8" for lid mounting) → LED LONG leg → LED SHORT leg → 220Ω → TB-LED3 Pos 1

Add Power Filtering Capacitors

⚡ CRITICAL FOR STABLE OPERATION! ⚡
Capacitors prevent voltage noise, random resets, and jumpy readings!
DO NOT SKIP THIS STEP!

What capacitors do:
They act like tiny rechargeable batteries that smooth out power fluctuations.
Think of them as shock absorbers for electricity!

Capacitor #1 - ESP32 Power Filtering:

0.1µF CAP

One leg → TB-PWR (any position)
Other leg → TB-GND (any position)

How to install:
1. Insert one capacitor leg into TB-PWR terminal
2. Insert other leg into TB-GND terminal
3. Tighten both screws
4. Capacitor should bridge between power and ground

Capacitor #2 - OLED Power Filtering:

0.1µF CAP

One leg → OLED VCC pin
Other leg → OLED GND pin

How to install:
1. Solder or twist one cap leg to OLED VCC wire
2. Solder or twist other leg to OLED GND wire
3. Keep capacitor close to OLED module
4. Use heat shrink or electrical tape to insulate

Capacitor #3 - Hall Sensor Power Filtering:

0.1µF CAP

One leg → Hall Sensor VCC pin
Other leg → Hall Sensor GND pin

How to install:
1. Solder or twist one cap leg to Hall VCC wire
2. Solder or twist other leg to Hall GND wire
3. Keep capacitor close to Hall sensor module
4. Use heat shrink or electrical tape to insulate

✅ Capacitors installed = Professional, stable EMF meter!
❌ No capacitors = Unreliable, noisy readings

Connect LED Terminals to Ground

Final step: Connect all LED terminal blocks back to main ground!

TB-LED1 (any position) ───> BLACK WIRE ───> TB-GND (any position)

TB-LED2 (any position) ───> BLACK WIRE ───> TB-GND (any position)

TB-LED3 (any position) ───> BLACK WIRE ───> TB-GND (any position)

💡 Why this works:
All LED terminal blocks share ground → all connect to TB-GND → TB-GND connects to ESP32 GND
Complete circuit!

Complete Connection Summary

TERMINAL BLOCK USAGE: TB-PWR (near battery): ├─ ESP32 3.3V ├─ OLED VCC └─ Hall Sensor VCC TB-GND (near battery): ├─ ESP32 GND ├─ OLED GND ├─ Hall Sensor GND ├─ TB-LED1 ground wire ├─ TB-LED2 ground wire └─ TB-LED3 ground wire TB-LED1 (near front panel): ├─ LED #1 resistor └─ LED #2 resistor TB-LED2 (near front panel): ├─ LED #3 resistor └─ LED #4 resistor TB-LED3 (near front panel): ├─ LED #5 resistor └─ [Spare position] DIRECT ESP32 WIRES (no terminals): ├─ GPIO 21 → OLED SDA ├─ GPIO 22 → OLED SCL ├─ GPIO 34 → Hall Sensor OUT ├─ GPIO 13 → LED #1 long leg ├─ GPIO 12 → LED #2 long leg ├─ GPIO 14 → LED #3 long leg ├─ GPIO 27 → LED #4 long leg └─ GPIO 26 → LED #5 long leg

Final Checklist

All 5-6 terminal blocks mounted in correct locations
TB-PWR has RED wires from ESP32 3.3V, OLED VCC, Hall VCC
TB-GND has BLACK wires from ESP32 GND, OLED GND, Hall GND
3× capacitors installed (TB-PWR to TB-GND, OLED power, Hall power)
OLED SDA (BLUE) goes directly to GPIO 21
OLED SCL (YELLOW) goes directly to GPIO 22
Hall OUT (GREEN) goes directly to GPIO 34
Each LED has resistor between SHORT leg and terminal block
All LED terminal blocks connected to TB-GND with BLACK wire
All screws snug but not overtightened
No bare wires touching

✅ WIRING COMPLETE!
Shorter wires, cleaner layout, easier to troubleshoot!
Now upload the firmware and test!

🖥️

Firmware Upload & Configuration

⚠️ CRITICAL: DISABLE WiFi & BLUETOOTH ⚠️
ESP32 WiFi/Bluetooth creates STRONG EMF interference!
Must be disabled in firmware to prevent false readings!

📚 Complete firmware upload guide:
→ Click here for full Arduino IDE setup and firmware upload tutorial ←

Required Code in setup():

Add this at the BEGINNING of setup() function:

void setup() {
  // DISABLE WIRELESS - Prevents EMF interference!
  WiFi.mode(WIFI_OFF);      // Disable WiFi
  btStop();                  // Disable Bluetooth

  // Rest of your setup code below...
  pinMode(LED1_PIN, OUTPUT);
  // etc...
}

Why This Matters:

ESP32 with WiFi ON: Creates 2.4GHz RF emissions = constant false EMF readings ❌
ESP32 with WiFi OFF: Minimal EMF = accurate external readings only ✅
Hall sensor positioned at front edge for best sensitivity
Internal components (OLED, LEDs, battery) produce negligible EMF
No shielding needed with WiFi/BT disabled!

✅ With WiFi/BT disabled, your EMF meter will only detect EXTERNAL sources!
Appliances, power lines, electronic devices - not your own circuit board!