Three-phase electrical systems are widely used in industrial environments to power heavy loads such as motors, compressors, and production machinery. Monitoring current in each phase is essential to detect imbalance, overload conditions, and potential equipment failure.

In this project, a 3-phase AC current data logger was developed to measure, record, and analyze current consumption in real time using current transformers (CT sensors) and a microcontroller-based data acquisition system.

System Objective

The primary goals of the system are:

• Measure RMS current for Phase R, S, and T
• Detect phase imbalance
• Log current data for analysis
• Provide serial or IoT-based monitoring
• Improve preventive maintenance capability

Hardware Architecture

Main components:

• 3× Current Transformer (CT) sensors
• Signal conditioning circuit (burden resistor + filter)
• Microcontroller (ESP32 / Arduino)
• LCD / OLED display (optional)
• Data logging interface (SD card / Serial / IoT)
• Isolated power supply

Each CT sensor converts AC current into proportional low-voltage AC signal. The signal is then conditioned and read by the microcontroller ADC.

CT Sensor (R,S,T) → Signal Conditioning → Microcontroller → Display / Logger

RMS Current Calculation

Because AC current is sinusoidal, RMS calculation is required.

Steps:

1. Sample waveform at high frequency
2. Square each sample
3. Compute mean value
4. Apply square root

Formula:

I_rms = √( (1/N) Σ i² )

This ensures accurate representation of effective current.

To improve stability:

• Moving average filter applied
• Zero-cross detection used (optional)
• Noise reduction capacitor implemented

Phase Imbalance Detection

Phase imbalance occurs when one phase carries significantly different current from the others.

Imbalance percentage is calculated as:

Imbalance % = (Max Deviation / Average Current) × 100%

If imbalance exceeds threshold (e.g., 10%), warning flag is triggered.

This prevents:

• Motor overheating
• Reduced efficiency
• Premature equipment failure

Data Logging Strategy

Several logging options can be implemented:

• SD Card data storage
• Serial monitoring via USB
• CSV export for Excel analysis

Sampling interval is configurable (1–10 seconds depending on application).

Industrial Engineering Insight

Unlike simple ammeters, this system provides:

• Continuous logging
• Imbalance detection
• Expandability to power calculation
• Remote monitoring capability

It can be upgraded to:

• Power factor monitoring
• kWh energy calculation
• Web-based dashboard
• Alarm system

Conclusion

The 3-Phase AC Current Data Logger demonstrates a practical solution for industrial electrical monitoring. By combining accurate RMS computation, phase imbalance detection, and structured data logging, the system improves reliability and predictive maintenance capability.

A flawless schematic won't save a bad layout.

Signal integrity loss. EMI noise. Unstable power delivery.

These aren't design flaws — they're layout problems. ⚠️

The gap between "looks right on screen" and "works in production" comes down to one thing: manufacturable layout.

✅ Proper component placement.

✅ Optimized routing.

✅ DFM-ready from day one.

That's exactly what JLCPCB's PCB Layout Service is built for.

Design it right. Ship it with confidence.👍

#PCBLayout #PCBDesign #JLCPCB #ElectronicsManufacturing #DesignForManufacturability

I do love making circuits that can power my car amplifier from my car battery. Not just because it is 12V but my amplifier system needs a dual rail power. This is the major problem in transistor based amplifiers because they need a higher voltage with a stable ground reference thus a dual rail power supply concept comes and it hurts me more when I just have a simple 12V battery. Something like +24V and -24V. You need a way to step that up and split it into two symmetric rails. The obvious thing that came to mind is using a transformer that can do it.

That's exactly what this module does. It's a pre-built push-pull DC-DC converter board that takes 12V DC in and outputs 24-0-24V (that's +24V and -24V with a centre-tap ground) at over 5A. I picked one up for an amplifier project, and I thought it was worth breaking down how it actually works. The controller IC running the show is the KA3525A, a classic SMPS controller that has been around for decades. I will show here how the push-pull topology works, and how to wire it up safely. For real-world power-on and load testing.

How to Use It:

Connect your 12V DC source to the input terminals. This module does not have a reverse voltage protection feature. Use a source capable of supplying enough current. At 5A output on the 24V rails, the input side draws significantly more 10-12A from the 12V supply due to the step-up ratio plus conversion losses. Use thick wires (at least 14-16 AWG) and a source rated accordingly. A 12V lead battery or a beefy 12V switching adapter works well. Avoid unregulated wall warts.

Connect +24V and -24V to your amplifier's V+ and V- supply pins. The 0V centre-tap connects to your amplifier's ground. Some push-pull converters can develop voltage at no-load because the feedback loop. Start with a light load and verify the output voltages with a multimeter before connecting your amplifier.

My Experience:

I got this module to pair with an audio amplifier that needed dual +/-24V rails but I only had a 12V bench supply handy. It delivered on its core promise stable +/-24V rails from 12V input, powering the amplifier, I have checked it using a multimeter. As the output capacitor charges it shows a significantly higher around 25V. But I have also tested it under some load for which the results are given here.

Build quality is what you'd expect from a generic module. The PCB is decent, solder joints are acceptable, and the IRFZ44N MOSFETs are genuine. The transformer is the biggest component on the board and it's wired reasonably well. What you need to find is just a good component vendor in case you are building something like this on your own.

#power convertor# #voltageConvertor# #PCB#

Most comparisons miss the real point.

👉 It comes down to how you control current:

• BJT → Current-controlled
• MOSFET → Voltage-controlled

This difference defines everything.

---

⚡ Quick Selection Table

Scenario	Use BJT	Use MOSFET
Analog (audio, amplification)	✅	❌
High-speed switching (PWM)	❌	✅
MCU control (3.3V/5V)	⚠️ Needs base current	✅ Easy
High current / power	❌ Inefficient	✅ Efficient
Simple low-cost circuits	✅	⚠️

---

🔥 Fast Decision Rule

• Amplifier → BJT
• Switch (motor, LED, SMPS) → MOSFET
• MCU GPIO → MOSFET (logic-level)

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In a real supercapacitor vs battery design, the goal is to choose a supercapacitor that can handle startup current spikes without causing voltage sag or stressing the battery. Selection is based on three parameters: voltage, capacitance, and ESR.

1. Voltage Rating (Series Cells)

Supercapacitors are rated ~2.5–2.7V per cell, so series connection is required.

• 12V system peak ≈ 14.4V
• Required cells: 14.42.7≈ 6

Design choice:

• Use 6–8 cells in series (≈16V rated bank)
• Include cell balancing (passive or active) to prevent overvoltage

2. Capacitance (Farad Selection)

Capacitance determines how effectively voltage sag is reduced during transients.

Note: Despite high capacitance (F), supercapacitors store less energy than batteries due to lower voltage.

Quick sizing guideline:

• Small loads → 0.1–1 F
• Medium loads → 1–10 F
• High surge (motors, inverters) → 10–50 F+

Oversize by ~2× for stability and aging margin

3. ESR (Critical for High Current)

Voltage drop under load: V=I×ESR

Example: 20A × 0.1Ω = 2V drop (unacceptable for 12V rail)

Target ESR:

• Moderate load → < 50 mΩ
• High surge → < 10–20 mΩ

4. Choosing Supercapacitor Type

• Cylindrical EDLC cells → best flexibility and performance
• Pre-balanced modules → simpler integration for higher voltage systems

5. Pre-Charge the Supercapacitor Bank (Critical Step)

A discharged supercapacitor behaves like a near short circuit, causing dangerous inrush current if directly connected.

Procedure:

Step 1: Insert a pre-charge element

• Power resistor (5–50Ω, high wattage) or NTC thermistor

Step 2: Estimate initial current: I_initial=V✖R

• Example: 12V / 10Ω ≈ 1.2A (safe)

Step 3: Allow gradual charging:

• Time constant: τ=R✖C

Step 4: Monitor voltage

• Wait until: Supercapacitor voltage ≈ battery voltage (within ~0.1–0.2V)

6. Switch to Direct Parallel Connection

Once pre-charged:

• Bypass the resistor using:

  • Relay / contactor (simple)
  • MOSFET switch (preferred for modern systems)

*******Connection sequence:

1. Pre-charge through resistor
2. Verify voltage match
3. Close bypass switch

→ Supercapacitor now directly in parallel

Figure: Circuit schematic of a 12V wind turbine hybrid power system. It details a 12V battery connected in parallel with a 6-cell supercapacitor bank, featuring a current-limiting pre-charge resistor and a bypass switch to safely manage inrush current.

⚠️ Engineering Notes

• Never connect a 0V supercapacitor directly to a battery

• Use proper wire gauge (high current path)

• Keep connections short (minimize inductance)

• Add protection:

  • Fuse or current limiting if required

\

Result

• Supercapacitor handles startup surge current

• Battery provides continuous energy

• System avoids:

  • voltage sag
  • battery stress
  • premature degradation

Key Takeaway: Always pre-charge a supercapacitor before connecting it in parallel with a battery - this prevents destructive inrush current and ensures stable hybrid operation.

Learn More: https://jlcpcb.com/blog/supercapacitor-vs-battery

**##supercapacitor# ##battery# ##supercapacitor_vs_battery#**

Because I am a sound lover, and in recent times I have done a lot of research on audio-related products. But I am always curious to measure the sound performance in terms of dB(A). In that way, when the amplifier is in steady state, I can measure the total output noise due to the surroundings. Because decibels are a logarithmic scale, it usually starts from a very light value, and it can also measure very high values. I have many options, as someone on the internet says, there are phone apps that claim to measure sound levels, but let's be honest, a phone microphone is designed for voice calls, not calibrated acoustic measurement.

So if you want to measure actual sound output, there are professional sound level meters, but they start at a couple of hundred dollars. But I wanted something in between a handheld dB meter that's actually accurate and battery-friendly. When I was searching the web, I came across the DFRobot Gravity Analog Sound Level Meter. This little board has a professional-grade MEMS microphone with proper signal conditioning. It has an A-weighting filter and a beautifully simple analog output. The voltage coming out is linearly proportional to decibels. So, no complex DSP, no FFT, just read an analog pin and multiply. I paired it with my own designed Arduino from JLCPCB and a 0.96" OLED display, and that’s how I got myself a proper handheld dB meter.

How the Code Works:

Because the sensitivity and conversions are based on ADC and they work on a reference. If that reference voltage is stable the readings are accurate. Arduino's 5V rail can vary from 4.6V to 5.2V depending on the host. And when running on battery, over the time as the battery discharges, there will be variations. To eliminate this issue, we used the `readVcc() function which takes the reference from the internal 1.1V bandgap of Arduino. This gives us the true supply voltage in millivolts, which we use in the dB calculation.

Raw sensor readings can be noisy. The code uses a circular buffer of 10 samples to compute a running average. This smooths out spikes while still responding quickly to changes (10 samples x 125ms = 1.25 seconds of averaging).

Here is how the ADC conversion is done:

A perfectly linear 0.6V-to-2.6V range mapping to 30-130 dBA. No lookup tables, no polynomial curve fitting, no complex calibration. Just multiply by 50. That's it. 0.6V = 30 dBA, 2.6V = 130 dBA.

dbValue = (analogRead(A0) / 1024.0) \* Vref \* 50.0;

Testing and Working:

I have tested the output in different scenarios, and it is working perfectly. Best to pair it directly with the Arduino with a soldering connection; a loose one may give you noise.

Testing with Songs:

Testing during conversation:

#PCB# #SOUND# #DB METER#