A Critical Resistor Pitfall You Didn't Know

Video Description

Free mini-course: https://www.hans-rosenberg.com/minicourse_account_youtube?utm_source=yt-d-v12 Full course info: https://www.hans-rosenberg.com/epdc_information_yt?utm_source=yt-d-v12 In this video I'll show you a critical pitfall in resistors and very simple ways to avoid it. Thanks to viewer comments, I found out some more information. I'm talking about thermal modulation, the resistor element having another temperature in the peaks and valleys compared to at the zero crossing. This effect is negligible at 1kHz for power resistors. The thermal mass (which I did not take into account when making this video) means the resistive element stays at a constant temperature. For smaller SMD resistors, this is different. They have a low enough thermal mass to cause problems in the 5-200Hz range. The effect drops of to 0 between 1kHz and 5kHz. You can find the information in this paper by Audio Precision. This company designs the best distortion measurement equipment in the world so they face this problem daily which means I trust them to be a very reliable source. https://www.ap.com/fileadmin-ap/technical-library/Designing_for_Ultra-Low_THD_N.pdf At 1kHz in the SMD demonstrations, another effect is dominating distortion: Voltage dependent resistance. This effect is really bad in thick film resistors and almost non-existent in thin film resistors (or better ones) as my real-life measurements show.