current sensor, voltage sensor at affordable cost - Xbotics
The 20A Range Current Sensor Module ACS712 consists of a precise, low-offset, linear Hall circuit with a copper conduction path located near the surface of the die. Applied current flowing through this copper conduction path generates a magnetic field in which the Hall IC converts into a proportional voltage.
This is a simple but very useful module which uses a potential divider to reduce an input voltage by a factor of 5. The Voltage Detection Sensor Module 25V allows you to use the analog input of a microcontroller to monitor voltages much higher than it capable of sensing.
ACS712 Current Sensor Module - 30A can sense upto 30A of current flow. Sensing and controlling the current flow is a fundamental requirement in wide variety of applications, which includes over-current protection circuits, battery chargers, switching mode power supplies, digital watt meters, programmable current sources, etc.