You may not know this, but using a spectrum analyzer to directly measure that 50 ohms thermal noise isn’t really doable as even top of the line Rohde & Schwarz FSWs state a Displayed Averaged Noise Level (in short, an instrument’s noise floor) between 71nV and 224nV RMS (-130dBm & -120dBm) at a 1Hz resolution bandwidth around kHz frequencies.
Moreover, every spectrum analyzer out there that is rated from a few Hz up also comes with a no DC input requirement! While the easiest solution to get around this issue usually is to use inline DC-blocking pass-through adapters, they however typically come with a low-pass filter corner frequency of a few hundred Hz… so what’s the solution?
A simple amplification circuit based on a low-input noise operational amplifier, with a clipper circuit at its output.
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 7pm ET! To join, head over to YouTube and check out the show’s live chat – we’ll post the link there.