Kerry Wong built a DIY constant current/constant power electronic load. It can sink more than 200W of power:
A while back I built a simple constant current electronic load using an aluminum HDD cooler case as the heatsink. While it was sufficient for a few amps’ load under low voltages, it could not handle load much higher than a few dozen watts at least not for a prolonged period of time. So this time around, I decided to build a much beefier electronic load so it could be used in more demanding situations.
One of the features a lot of commercial electronic loads has in common is the ability to sink constant power. Constant power would come in handy when measuring battery capacities (Wh) or testing power supplies for instance. To accommodate this, I decided to use an Arduino (ATmega328p) microcontroller.
Building a constant current/constant power electronic load - [Link]
Paul over at Dorkbotpdx writes:
Recently I needed to actually “see” a current waveform in the 100 uA to 5 mA range with at least a couple MHz bandwidth. This extremely expensive probe would have been perfect, but instead I built something similar for about $30 using the amazing Analog Devices AD8428 amplifier.
Measuring microamps & milliamps at 3 MHz bandwidth - [Link]
FluxProbe is a test prod for measuring currents without touching the conductor it is flowing through. More acurately it is measuring the magnetic flux. This way you can measure currents on PCB traces without having to put a resistor in between. This test gear enables you to trace faults in your PCB (for example search for a short circuit). This is usefull for commissioning of you circuit for example.
FluxProbe – measure currents without touching the conductor - [Link]
Christian Aurich wanted a way to measure current on PCBs without having to cut the traces. He concluded building a probe able to measure current using a Hall Effect sensor. It’s on prototyping phase, so improvements are yet to come. He writes:
In the last weeks I followed an idea to measure current without the need to cut the wires or even open a pcb trace. The solution i came up with is a hall effect based measurement.
I wrote some more about it in an article here: http://avrs-at-leipzig.de/dokuwiki/en/prokekte/fluxprobe
Building a current / flux probe for contactless measurements - [Link]
Here is a PDF document from Linear Technology, featuring current sense circuits for different applications, including High side, low side, level shifting, high and low voltage, fault sensing, etc: [via]
Sensing and/or controlling current flow is a fundamental requirement in many electronics systems, and the techniques to do so are as diverse as the applications them-selves. This Application Note compiles solutions to current sensing problems and organizes the solutions by general application type. These circuits have been culled from a variety of Linear Technology documents.
Current sense circuit collection - [Link]
The INA230 is a current-shunt and power monitor with an I2C interface that features 16 programmable addresses. The INA230 monitors both shunt voltage drops and bus supply voltage. Programmable calibration value, conversion times, and averaging, combined with an internal multiplier, enable direct readouts of current in amperes and power in watts.
INA230 – Precision digital/current/voltage/power monitor - [Link]
This application note describes the use of current-sense amplifiers, differential amplifiers, and instrumentation amplifiers to measure battery charge and discharge currents in smartphones, tablets, computer notebooks, and USB accessories. It compares high-side current sense amplifiers with low-side differential amplifiers and recommends selection criteria for current-sense resistors. A high-voltage circuit breaker is described to provide system over-current protection due to faults and short circuits. Application circuits for a variable linear current source and a programmable 0–5A current source are included.
High-Side Current-Sense Measurement: Circuits and Principles - [Link]
INA219 is a cool IC that measures voltage and current trough a shunt resistor, and relays the information over I2C. It provides the multiple of the two values, thus enabling easy power measurement. Opossum used it along with a Nokia 5110 LCD and a MSP430 LaunchPad to build a nice power-meter.
Measuring power with INA219 and an MSP430 Launchpad - [Link]
Jon Gabay writes:
Current measurement and control are an integral part of any power sensitive system. While most of us have used ammeters to measure current, it is unlikely that budget, space and other practical constraints will allow design engineers to specify an ammeter as part of a finished product; more likely, we will embed some current measurement technique within a given design.
Current measurement has a wide range of uses. Some of these are:
- Making sure a power supply is not damaged by receiving too much current.
- To estimate the rotational speed of a motor (the speed of a motor is directly proportional to the amount of current applied to it).
- To check whether an LED has correct illumination.
- To determine how much current is being applied to a battery pack during charging (so as to prevent overcharging or overheating the batteries).
- To measure the amount of current being applied to a circuit from the battery pack, enabling estimation of the battery life.
Active Current Measurement Saves Power, Enhances Safety - [Link]