The ZMCT103C AC Current Transformer Module is a high-precision sensor designed to measure AC current safely by providing electrical isolation between the high-voltage AC line and your low-voltage microcontroller. At Electrapac, we recommend this module for engineers and hobbyists in Bangladesh building energy monitors, smart home switches, or overcurrent protection systems with Arduino and ESP32.

The ZMCT103C works on the principle of electromagnetic induction. By passing an AC wire through the center of the "donut" (the transformer), it induces a tiny, proportional current in the module. An on-board OP-07 operational amplifier and a potentiometer then convert and scale this signal into a measurable analog voltage. This allows your 5V Arduino to "see" how much power a 220V appliance is drawing without any direct electrical contact.

Key Features for Electrapac Customers

• Safe Non-Contact Sensing: Because the AC wire only passes through the hole, there is no physical connection to the mains, keeping your Arduino and yourself safe from high-voltage shocks.

• On-Board Signal Conditioning: Includes a precision Op-Amp circuit that boosts the tiny induced signal into a clear 0–5V analog wave that is easy for a microcontroller to process.

• Adjustable Gain: Features a multi-turn potentiometer. You can fine-tune the output voltage range to match the specific current draw of your appliance.

• Ultra-Compact Design: The vertical mounting of the ZMCT103C transformer saves valuable space on your PCB or breadboard.

• High Precision: Offers excellent linearity and low phase shift, which is critical for calculating "True Power" (Watts) in AC circuits.

Using the Electrapac ZMCT103C requires careful attention to the AC line you are measuring:

1. AC Connection: Pass ONLY ONE of the two AC wires (either Live or Neutral) through the hole of the blue transformer. If you pass both wires through, the magnetic fields will cancel out, and the sensor will read zero.

2. VCC/GND: Connect to 5V and Ground.

3. OUT (Analog): Connect to an Analog Pin (e.g., A0).

4. The Output Wave: Note that the output is an AC sine wave centered around a DC offset (usually 2.5V). To get the current in Amps, you must sample the wave quickly in your code and calculate the RMS (Root Mean Square) value.

Pro-Tip: If you are measuring a very small current (like a phone charger), you can wrap the AC wire through the hole 5 or 10 times. This "multiplies" the signal strength, making it much easier for the sensor to detect low-power devices.

• IoT Energy Monitors: Tracking the electricity consumption of fans, lights, or computers in real-time.

• Overload Alarms: Automatically cutting power (using a relay) if a motor or heater draws more than 5A.

• Appliance Status Detection: Checking if a water pump or AC unit is actually running by detecting current flow.

• Smart Power Strips: Building custom power bars that report energy usage to a mobile app via WiFi.

• Educational Lab Gear: Demonstrating the principles of transformers and induction in physics projects.

We source our ZMCT103C Modules with high-precision internal resistors to ensure the output remains linear across the entire 0-5A range. Visit us at www.electrapac.com for the power-sensing components that give you total insight into your energy usage.