DAOKAI 5A Current Sensor ZMCT103C Single Phase AC Current Transformer Module Active Output Sensor Board with Cable, Pack of 5

This is a reasonable clone of the ZMCT103C, AC only current sensor. As its an AC sensor, it cannot be used for DC currents. Look at the Allegro ACS711 series if you need to measure DC currentsAs the currents will typically be from a mains powered device operating at 50Hz, you need to process the data coming out of the sensor to convert the instantanous value to the actual RMS AC current value using a rolling peak detection routine that then converts to RMS (multiply by 0.707), then scale for the 1V max output voltage.Various examples are given on-line on how to process this, Cirkit designer and Electropeak both give good examples. OSHWlab also has a full schematic of the board for those that want to understand the details of how it works, but there are many more too.The sensor input requires that either the live or neutral wire is fed through the current transformer (CT), before being reconnected to its original termination, meaning that a magnetic coupling is achieved, which is insulated from the high voltage source, thus making the adapter safe as there are no hazardous voltages present, however if you are playing with mains, then be very careful and make sure you understand what you are doing.The sensors output is an instantaenous value in the range of 0-1V, that correlates to an input current of 0-5A. The gain off the sensor can be adjusted with the potentiometer.To calibrate the sensors gain, you can put a suitable multimeter in series with the wire going throuh the sensor and adjusting until the software value matches the meter value in milliamps.The sensor is provided with just enough jumper wires to connect to the 5 current sense modules, but no instructions are provided and the 0.1 pitch headers have not been soldered in straight, so these were the first thing that got corrected on mine.

I'm confused by the 1 star reviews for this product, if you have a look in the datasheets or any of the example libraries using this (ZMCT103C Arduino will find you some code), you can see that you will need to calibrate this with a load, if you do this, it works well for determining larger differences in current.Its not mA accurate, but can you tell between 1 and 2 Amps of AC draw, sure.Cheap, you get 6 for the price, quality is good, they work with all the libraries supporting this CT, so this is good value in my eyes.