Varistors (VDRs, or Voltage Dependent Resistors) are one of those humble components that quietly protect your circuits from transient overvoltage events — lightning strikes on the mains, inductive kickback from motors, ESD on signal lines — yet they rarely get proper attention in beginner electronics tutorials. This French-language video from Go Tronic walks through the fundamentals of how a varistor works, focusing on its nonlinear V-I characteristic: below the clamping voltage it looks essentially like an open circuit, and above it, resistance collapses dramatically, shunting the surge to ground.

What you'll learn: the physics behind metal-oxide varistors (typically zinc oxide grains acting as back-to-back diode junctions), how to read the datasheet parameters that actually matter (clamping voltage, maximum continuous voltage, energy absorption rating in joules), and where varistors fit in a real protection scheme versus TVS diodes or gas discharge tubes.

Go Tronic is a well-regarded French electronics component distributor, and their tutorial channel tends to keep explanations grounded and practical rather than hand-wavy. If you're comfortable with French (or comfortable with auto-generated captions), this is a solid 101 on a component that every mains-connected or motor-driving project should include but that too many hobbyists skip.