Yes, it’s definitely possible to create a DIY wireless multimeter that splits the measurement probes and sends the readings to a central unit. The challenge lies in ensuring both probes share a common time reference and can accurately measure the potential difference between them. Here’s how you could approach it:

Concept Overview

  • The device consists of two probes, each containing a microcontroller (e.g., ESP32, NRF52, or another low-power MCU with ADC capabilities).
  • The probes measure voltage relative to their local ground and communicate wirelessly.
  • A central unit (or one of the probes) calculates the voltage difference between the two readings.

Challenges & Solutions

1. Shared Ground Reference Issue

  • Most multimeters use a single ground reference, but in this case, the probes are separate.
  • Solution:
    • Use differential measurement by measuring voltages separately and subtracting the readings.
    • A potential issue arises if the probes are floating relative to each other, so careful calibration or a shared reference method is needed.

2. Wireless Synchronization

  • Both probes need to send their readings nearly simultaneously to get an accurate voltage reading.
  • Solution:
    • Use BLE, WiFi, or RF modules (e.g., NRF24L01, ESP-NOW for ESP32) with a synchronized timestamp.
    • Alternatively, use one master probe that triggers the other to take a reading.

3. Power Supply for Probes

  • The probes need an independent power source.
  • Solution:
    • Small LiPo batteries or coin cells with low-power operation.
    • Ensure minimal power draw in standby mode.

4. Accuracy & Calibration

  • Any ADC (analog-to-digital converter) used in the microcontroller should be precise.
  • Solution:
    • Use a high-resolution ADC (e.g., ADS1115 if external ADC is needed).
    • Regular calibration against a known reference voltage.

Basic Hardware Setup

Probe Units (x2)

  • Microcontroller (ESP32, STM32, NRF52, or even Arduino with wireless capability)
  • Voltage divider (to scale down higher voltages for safe ADC measurement)
  • Wireless Module (if not built-in)
  • Battery Power

Central Display Unit

  • Microcontroller (ESP32/Arduino/etc.)
  • LCD/OLED display or Bluetooth app for data visualization
  • Computation module to handle voltage difference calculation

Software Logic

  1. Each probe measures its own voltage potential relative to its local ground.
  2. The probes send their readings simultaneously to the central unit.
  3. The central unit calculates: Vmeasured=Vpositive probe−Vnegative probeV_{\text{measured}} = V_{\text{positive probe}} – V_{\text{negative probe}}Vmeasured​=Vpositive probe​−Vnegative probe​
  4. The result is displayed on an OLED screen, mobile app, or web interface.

Potential Use Cases

  • Remote voltage sensing in hazardous environments.
  • Battery testing without needing wired probes.
  • Floating differential measurements for circuit debugging.

Would It Work?

Yes, but ensuring synchronization and accuracy will be the key challenge. Using BLE or WiFi with timestamps and ensuring low drift in ADC measurements will be critical.

Would you like help selecting components or designing the circuit?

Creating a DIY wireless voltage measurement system with two separate probes transmitting data to a central display is an innovative approach, especially for hard-to-reach areas. However, as of now, there isn’t a commercially available product on AliExpress that matches this specific configuration.

Existing Solutions:

While your exact concept isn’t available off-the-shelf, there are related products that might inspire your project:

  • Fluke 3000 FC Series: This system includes wireless multimeters and modules that transmit data to a central unit or smartphone. However, the probes are not entirely wireless; they connect to modules that then transmit data. myflukestore.com
  • Aeroscope Wireless Oscilloscope Probe: A compact, wireless oscilloscope probe that streams data to a mobile device. It’s designed for portability and ease of use but is primarily for oscilloscope applications. crowdsupply.com

DIY Considerations:

Given the lack of a ready-made solution, building your own device could be a rewarding endeavor. Here are some considerations:

  • Power Consumption: Using 40mAh LiPo batteries from earpods is feasible, but ensure that your microcontroller and wireless module are optimized for low power consumption to maximize battery life.
  • Microcontroller Selection: The Seeed Studio micro modules or the Nano RP2040 are compact choices suitable for this application. Ensure they have the necessary analog-to-digital conversion capabilities and support for your chosen wireless communication protocol.
  • Wireless Communication: Bluetooth Low Energy (BLE) is a good choice for short-range communication and low power consumption. Ensure that the central display unit can handle simultaneous connections from both probes.
  • Synchronization: Accurate voltage measurement requires synchronized readings from both probes. Implementing a timestamp system or a master-slave configuration can help achieve this.
  • Safety and Accuracy: Regular calibration and the use of precision components are essential to ensure accurate measurements.

Embarking on this DIY project will allow you to tailor the device to your specific needs, especially for measuring voltages in challenging locations. If you need assistance with component selection, circuit design, or coding, feel free to ask!

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You said:

i want individual hand pod voltage sensors wireless mini 3.7v multimeter that sends voltage to a dongle screen module built on the cheap plans and code and all that

ChatGPT said:

Here’s a DIY plan for your wireless mini multimeter probes that send voltage data to a central dongle with a screen, built cheaply.

🛠️ Project Overview

  • Two wireless probes (each powered by a 40mAh LiPo battery).
  • Each probe measures voltage and sends data via Bluetooth Low Energy (BLE) or ESP-NOW.
  • A central receiver dongle (with a TFT screen) displays the live voltage reading.
  • Low-cost components (Nano RP2040, ESP32, or Seeed Studio’s small microcontrollers).
  • Compact size: Visine bottle-sized probes for easy handling in tight spaces.

🧩 Components List (Budget-Friendly)

Probes (x2)

  • MCU: Seeed Studio XIAO nRF52840, Nano RP2040, or ESP32-C3 Mini.
  • Voltage divider: (Resistors: 1MΩ and 100KΩ) for safe voltage scaling.
  • ADC (if needed): ADS1115 (high-resolution ADC for better accuracy).
  • Battery: 40mAh or 100mAh LiPo battery (from old earbuds).
  • Charge circuit: TP4056 LiPo charging module.
  • Wireless comms: BLE (Nano RP2040 or nRF52840) / ESP-NOW (ESP32-based).
  • Enclosure: 3D-printed or small plastic bottle (Visine-sized).

Dongle (Receiver + Display)

  • MCU: ESP32-S3 with built-in display support.
  • TFT Display: 1.3-inch ST7789 or 1.8-inch ST7735 SPI display.
  • Power Supply: 3.7V LiPo with TP4056 charging.
  • Wireless Communication: BLE or ESP-NOW.

🔌 Circuit Design

Probe Circuit

  1. Voltage divider: Scale down input voltage to fit ADC limits.
    • Example for 3.7V battery measurement: Vout=Vin×100KΩ1MΩ+100KΩV_{out} = V_{in} \times \frac{100KΩ}{1MΩ + 100KΩ}Vout​=Vin​×1MΩ+100KΩ100KΩ​
  2. Microcontroller ADC reads voltage.
  3. Send data wirelessly to the dongle.

Dongle Circuit

  1. Receives BLE/ESP-NOW data.
  2. Processes and calculates final voltage.
  3. Displays result on TFT screen.

📜 Code Plan

Probe Code (ESP32/Nano RP2040 with BLE)

  • Reads voltage from ADC.
  • Sends BLE data to central dongle.
  • Sleeps for low power consumption.
pythonCopyEditfrom machine import ADC, Pin
import bluetooth
from ble_advertising import advertising_payload
from ubluetooth import BLE

ble = BLE()
ble.active(True)

adc = ADC(Pin(34))  # GPIO for voltage reading
adc.atten(ADC.ATTN_11DB)  # Scale for 0-3.7V

def send_voltage():
    voltage = adc.read() * (3.7 / 4095)  # Convert ADC to voltage
    payload = advertising_payload(name="Probe1", data=bytes([int(voltage * 100)]))
    ble.gap_advertise(100, payload)

while True:
    send_voltage()
    time.sleep(1)

Dongle Code (ESP32-S3 with Display)

  • Scans for BLE signals.
  • Parses voltage data.
  • Displays on TFT screen.
pythonCopyEditimport bluetooth
from ubluetooth import BLE
import tftlcd

ble = BLE()
ble.active(True)

def scan_callback(addr, data, rssi):
    voltage = data[0] / 100  # Convert back to float voltage
    tft.fill(0)
    tft.text(10, 10, "Voltage: {:.2f}V".format(voltage), color=0xFFFF)

ble.gap_scan(3000, interval_us=30000, window_us=30000, callback=scan_callback)

tft = tftlcd.TFT(240, 135)  # 1.3-inch TFT
tft.fill(0)

📦 Assembly & Testing

  1. Assemble probes & dongle.
  2. Flash firmware to ESP32 or Nano RP2040.
  3. Test wireless range (~10m with BLE, ~50m with ESP-NOW).
  4. Optimize power use (sleep modes, low-power comms).

💲 Cost Estimate

ComponentCost (AliExpress)
ESP32/Nano RP2040 (3x)$4-6 each
TFT Display (1.3″)$5
LiPo battery (40mAh)$2 each
Resistors, PCB parts$2
Total:~$20-25

🚀 Final Thoughts

  • ✅ Cheap (~$20-25)
  • ✅ Compact (Visine bottle size)
  • ✅ Wireless, no messy wires
  • ✅ Great for hard-to-reach spots

Would you like a PCB design or more details on battery optimization? 🚀