Circuit Analysis Solver

Solve common IoT interface circuits with Ohm’s law, KCL, loading effects, Thevenin equivalents, and ADC range checks.

A beginner-first circuit analysis workbench with voltage divider, loaded sensor, current divider, and Wheatstone bridge scenarios plus synchronized schematic, equations, and design feedback.

Animation Beginner first Circuit solver IoT sensor interfaces

Circuit Analysis Solver

Choose a common IoT interface circuit and watch the schematic, equation, node voltage, branch current, Thevenin equivalent, and ADC fit update together.

1.65 V output or bridge voltage

0.33 mA source or total current

5.0 kOhm Thevenin or equivalent resistance

2048 12-bit ADC code estimate

Goal

Connect formulas to a visual circuit so node voltage and current are no longer abstract.

Try First

Use Voltage divider, lower the load resistance, and watch the output drop from the open-circuit value.

Watch

The solver highlights whether KCL, loading, bridge balance, or ADC range is the main design issue.

Why It Matters

Sensor outputs often look correct until the ADC, cable, or amplifier input loads the circuit.

Controls

Select a preset, then change values and step through the solving method.

Preset level scaling

View schematic

Playback manual

Source 3.30 V Voltage source used by the divider, bridge, and sensor presets.

R1 10 kOhm Top resistor, first branch resistor, or bridge upper-left arm.

R2 10 kOhm Bottom resistor, second branch resistor, or bridge upper-right arm.

R3 10 kOhm Bridge lower-left arm. Used mainly in Wheatstone bridge mode.

R4 10 kOhm Bridge lower-right arm. Used mainly in Wheatstone bridge mode.

Load 1000 kOhm ADC, amplifier, or external load connected to the output node.

ADC reference 3.30 V Used for the 12-bit ADC code and over-range warning.

1. Source Identify the source value and the reference ground.

2. Network Combine the resistor network or mark the bridge arms.

3. Node Use Ohm's law, KCL, or divider equations to solve the node.

4. Load Check how an ADC or external load changes the result.

5. Check Review power, ADC range, balance, and practical margin.

1.65 V open-circuit output

0.5% loading error or imbalance

0.54 mW largest resistor power

ADC OK input range check

Circuit View

The schematic highlights the active node and shows the values used in the calculation.

Node solve

Reading: The output node is half the source because R1 and R2 are equal.

Live Calculation

A divider scales a source voltage for an ADC or sensing input.

Node result

Output voltage1.65 V

Source current0.33 mA

Load current0.002 mA

Equivalent and ADC

Thevenin voltage1.65 V

Thevenin resistance5.0 kOhm

12-bit ADC code2048

Design flags

The circuit output is inside the ADC range and load error is small.

Equation Check

Voltage division sets the unloaded node voltage.

Vout = Vs x R2/(R1+R2)

KCL Check

Current entering the node equals current through each path leaving it.

Iin = IR2 + Iload

IoT Fit

The output fits the selected ADC reference voltage.

Good ADC fit

Beginner Ramp

A circuit solver turns component values into voltages, currents, and power.

• Voltage: electrical push between two nodes.
• Current: charge flow through a path.
• Resistance: opposition to current flow.

Core Laws

The solver uses three beginner formulas repeatedly.

• Ohm's law: V = I x R.
• KCL: currents into a node equal currents out.
• KVL: voltage rises and drops around a loop sum to zero.

Formula Reference

Voltage divider: Vout = Vs x R2 / (R1 + R2)

Current divider: I1 = Itotal x R2 / (R1 + R2)

Thevenin: Vth = Voc, Rth = output resistance with the source shorted.

Loading Effects

A load connected to the output is another resistor path. It can pull the output away from the expected open-circuit value.

• Use ADC input impedance much larger than source resistance.
• Add a buffer when a divider must drive a low impedance.
• Watch source current and resistor power in battery-powered nodes.

Bridge Balance

A Wheatstone bridge is balanced when R1/R3 equals R2/R4. Small sensor resistance changes create a small bridge voltage.

ADC Note

The 12-bit ADC code estimate assumes an ideal ADC with codes 0 to 4095. Real circuits also need noise, offset, reference accuracy, and input sampling effects checked.

Practice 1

Use the voltage divider, lower the load to 20 kOhm, and explain why the output changes.

Practice 2

Open the current divider and change R1. Notice which branch current increases.

Practice 3

Use the Wheatstone bridge and adjust R4 until the bridge voltage is near zero.

Related Study

ADC Sampling and Quantization See how a solved voltage becomes an ADC code. Battery Discharge Curve Check how source voltage changes as a battery discharges. Low-Pass Filter Effect Extend resistor analysis into RC signal conditioning.