115th Birthday of Harold S. Black, Inventor of the Negative Feedback Amplifier
Today would be the 115th birthday of Harold Stephen Black, who invented the negative-feedback amplifier in 1927. The story goes that Mr. Black was taking the ferry from New Jersey to New York City (where Bell Labs was then located), and while on the boat he was struck by the idea to use negative feedback to linearize an amplifier stage.
The idea of negative feedback is a powerful one, because it provides a means to construct amplifiers with precise gain characteristics from parts with less than ideal specs. This makes it easier to build circuits with interchangeable, off-the-shelf parts. Gain can be adjusted using passive components, which are cheaper and easier to adjust.
Distortion and intermodulation are reduced significantly, and bandwidth is greatly increased. It also enables the construction of higher order filters without the use of inductors, which are heavy and prone to other problems. Though initially developed for vacuum tubes, the idea is very useful in transistor circuits, which can have wildly varying beta characteristics, even among devices on the same chip.
There are a lot of things to like about the video above, but my favorite part is the way he talks so earnestly about his failures, before finally succeeding.
8-6-2021 (August 6, 2021) is the Snakiest day of the year and it’s also this year’s CircuitPython Day! The day highlights all things CircuitPython and Python on Hardware. See you there!
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.