Maker Gerard Morsink has designed a device designed to perform I-V curve tracing for transistors, diodes, and other components — feeding data to a custom-made graphical user interface written in Python.
“This project builds an I-V curve tracer connected to a computer using USB,” Morsink explains of his work. “A curve tracer is a type of instrument used to measure the current through a device with varying voltages across it. It is a specialized piece of electronic test equipment to analyze the characteristics of discrete electronic components, such as diodes, and transistors. The device contains voltage and current sources that can be used to stimulate the device under test (DUT). The curve tracer applies a continuously varying voltage to two terminals of the device under test and measure the amount of current that the device permits to flow at each voltage.”
An ATmega8-powered curve tracer provides a way to quickly check your components — without breaking the bank. (📷: Gerard Morsink)
Commercial curve-tracing test equipment is readily available, but Morsink’s gadget is built for those on a budget — using the low-cost Microchip ATmega8 microcontroller at its heart, and relying on its internal analog to digital converter (ADC) for taking the readings. Despite the small size of the microcontroller, Morsink says there’s capacity as-yet unused — “more modes and functions can be created in the future,” he notes.
The testing device is designed to stream its readings to a host computer over USB, communicating with a graphical Python application Morsink wrote specifically for the project. Once calibrated — as simple as putting a 1kΩ resistor between the collector and emitter pins and performing a single-shot measurement then adjusting as required — the curve tracer does exactly what you’d expect, tracing the response curves of components including LEDs, PNP transistors, and NPN transistors.
The project is documented in full on Hackaday.io, while the hardware design files and source code for the software and firmware are available on GitHub under the permissive MIT license.
