The rest of the circuit is quite simple: only two capacitors, an inductor, and a resistor are needed. [Valentine] does note that the circuit is quite sensitive, so you might encounter issues when ...

But there are a number of problems with this simple method ... that keeps the current between the unknown resistor and the rest of the circuit at zero. This prevents current flowing except ...

Using properties of a series circuit, the sum of the voltages across the LED and resistor R must equal the supply voltage. \({V_s} = {V_{LED}} + {V_R}\) Now substitute the supply voltage (\(6V ...

Moving the position of the slider on this resistor, changes the length of wire in the circuit which changes the resistance. A variable resistor is used in some dimmer switches and volume controls.