Free university-style lectures
Video lectures, notes and worked answers, from A Level to first-year university
Each lecture teaches the A Level ideas first, then the first-year maths. Every page is checked against its sources before it goes up.
Start where you are
Course 1
Signals and Sound
From "what is a signal?" to the door of second-year signal processing: sampling, bits, decibels, converters, filters, harmonics, the spectrum, amplifiers, digital filters, effects and convolution. Each lecture teaches the A Level layer first, then goes deeper for first-year students.
12 lectures planned · Lecture 1 available
- 1Sound, signals and sampling
- 2Bits and resolution
- 3Decibels and loudness
- 4From analogue to digital and back
- 5Filters I: RC low-pass and high-pass
- 6Filters II: active filters and tone controls
- 7–12Harmonics and timbre, The spectrum, Amplifiers for audio, Digital filters, Effects, Convolution and impulse responses
By subject and exam board
One lecture often serves several subjects. Pick yours to see which lectures teach your specification, section by section.
How it is made, and how it is checked
An AI-generated presenter
Professor Kettlewick is an AI character, not a real person. The courses are written from published specifications and textbooks, and made by DigitalZoo.ai.
Checked twice against sources
Claude and ChatGPT each review every page independently against its cited sources, and every numerical answer is recomputed by code.
A lecturer's check, shown separately
When a university lecturer has checked a lecture, its page says so and when. Until then it says the check is pending.