CIRCUIT BUILD 06 · Voltage Dividers

Building a Voltage Divider Circuit

Two resistors in series can tap off any voltage you need between zero and your full supply.

You'll need: a DC supply, two resistors, a breadboard, and a multimeter set to measure DC voltage.

Wire two resistors in series across your supply, and the point between them — the junction — sits at a voltage somewhere between 0V and the full supply, determined entirely by the ratio of the two resistor values. This is a voltage divider, one of the most-used building blocks in electronics.

The formula: V_out = V_supply × R2 / (R1 + R2), where R1 is the resistor connected to the positive supply and R2 is the resistor connected to ground, and V_out is measured at their junction. Equal resistor values split the voltage exactly in half; a larger R2 relative to R1 pushes the output voltage higher.

Build it with two 10kΩ resistors across a 9V supply, then confirm with your multimeter that the junction reads close to 4.5V. This exact circuit — a fixed divider or its variable cousin, the potentiometer (next lesson) — is how countless sensors and controls create an adjustable or scaled-down voltage from a fixed supply.

Two resistors, one tap The junction between R1 and R2 sits at a voltage set purely by their ratio — the basic voltage-divider arrangement.

BUILD TIP

V_out = V_supply × R2/(R1+R2) — two series resistors are the simplest way to scale a fixed supply down to any voltage you need.

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