An adjustable load – design and build @technoblogy
Technoblogy presents an adjustable load that provides a constant-current load for testing power supplies and batteries. It allows setting the load current to up to 1.05A, using a potentiometer, and displays the current on a three-digit LED display controlled by an ATtiny84.
As well as testing power supplies, the adjustable load can be used for testing rechargeable NiMH and Li-ion batteries under different load conditions. It measures the current over time, and displays the battery’s capacity in mAh or Ah. This is useful for comparing different makes of battery, or for deciding whether a battery has reached the end of its life.
The constant-current circuit is based on an LT3080 regulator. This uses a current reference of 10µA, rather than a voltage reference like regulators such as the LM317, and will operate down to 1.5V and a few mA.
The current is sensed by a 1Ω resistor, and this is fed to the sense input of the regulator, via a 100kΩ potentiometer and 5.1kΩ resistor. Since the current through the potentiometer and resistor is 10µA, at the potentiometer’s maximum setting the voltage across them will be 1.05V, so the output of the regulator will be maintained at 1.05V across the 1Ω resistor, producing a constant current of 1.05A.
The current is displayed on a three-digit 7-segment display. I used a 0.28″ three-digit common anode seven-segment LED display.
Adafruit publishes a wide range of writing and video content, including interviews and reporting on the maker market and the wider technology world. Our standards page is intended as a guide to best practices that Adafruit uses, as well as an outline of the ethical standards Adafruit aspires to. While Adafruit is not an independent journalistic institution, Adafruit strives to be a fair, informative, and positive voice within the community – check it out here: adafruit.com/editorialstandards
Stop breadboarding and soldering – start making immediately! Adafruit’s Circuit Playground is jam-packed with LEDs, sensors, buttons, alligator clip pads and more. Build projects with Circuit Playground in a few minutes with the drag-and-drop MakeCode programming site, learn computer science using the CS Discoveries class on code.org, jump into CircuitPython to learn Python and hardware together, TinyGO, or even use the Arduino IDE. Circuit Playground Express is the newest and best Circuit Playground board, with support for CircuitPython, MakeCode, and Arduino. It has a powerful processor, 10 NeoPixels, mini speaker, InfraRed receive and transmit, two buttons, a switch, 14 alligator clip pads, and lots of sensors: capacitive touch, IR proximity, temperature, light, motion and sound. A whole wide world of electronics and coding is waiting for you, and it fits in the palm of your hand.
Have an amazing project to share? The Electronics Show and Tell is every Wednesday at 7:30pm ET! To join, head over to YouTube and check out the show’s live chat and our Discord!
Python for Microcontrollers – Adafruit Daily — Python on Microcontrollers Newsletter: New Python Releases, an ESP32+MicroPython IDE and Much More! #CircuitPython #Python #micropython @ThePSF @Raspberry_Pi
EYE on NPI – Adafruit Daily — EYE on NPI Maxim’s Himalaya uSLIC Step-Down Power Module #EyeOnNPI @maximintegrated @digikey
