Output Voltage Calculator

Plotly output trend

Output voltage as a verification target

Output voltage is the first checkpoint in power and analog design. If a 5.0 V rail drifts by 2%, many ICs move closer to undervoltage lockout, and ADC references lose margin. This calculator focuses on common building blocks and returns Vout with a recorded input summary for repeatable checks. It also helps keep revisions consistent during reviews.

Divider ratios and practical limits

For a resistive divider, Vout depends on the ratio R2/(R1+R2). A 12 V source with 10 kΩ and 5 kΩ yields 4.0 V, but a load in parallel with R2 increases the ratio error. Keeping divider current at least ten times larger than load current is a useful rule of thumb. Temperature drift of resistors adds small but measurable offsets.

Non-inverting gain planning

Non-inverting amplifiers scale voltage without phase inversion using 1+Rf/Rg. With Vin at 0.30 V, a gain of 10 targets 3.0 V. Select resistor values that limit noise and bias-current error; tens of kilohms are common. Always compare the computed output to the available output swing for your supply rails. Add headroom for transient peaks and startup behavior.

Inverting stages and polarity awareness

Inverting amplifiers use −Rf/Rin, producing a negative output for a positive input when referenced to ground. This is useful for summing and level shifting, but it can surprise during validation. The calculator reports the sign explicitly, helping you confirm whether your stage requires a reference offset or a split supply. Check input common-mode limits in single-supply designs.

Transformer scaling and downstream conversion

Turns ratio provides an ideal voltage scale: Vout = Vin×Ns/Np. A 230 V primary with 52 turns on the secondary of a 1000-turn primary predicts about 11.96 V RMS. Real transformers drop under load, so treat the result as nominal, then combine it with the rectifier estimate for DC headroom checks. Regulation values vary widely by core and rating.

Rectifier peak budgeting with diode drops

Rectified peak is Vrms×√2 minus diode drops. With 12 Vrms, the peak is 16.97 V. Subtracting two 0.85 V drops gives roughly 15.27 V no-load. Under load, ripple and diode heating reduce average voltage. Use session history and the graph to compare alternatives and document assumptions. Export results to share.

FAQs

Which mode fits a basic two-resistor scaling network?

Choose voltage divider. Enter Vin, R1, and R2 to compute the node voltage. If the node is loaded by an input, reduce resistor values or buffer the node, then re-check expected Vout.

Why can an amplifier result be correct but impossible on hardware?

Ideal gain formulas ignore supply rails and output swing. If computed Vout exceeds the op-amp’s swing or current limit, the device clips. Verify output range, load, and headroom against the datasheet.

How should I select resistor magnitudes for op-amp gains?

Keep ratios correct, then pick values that balance noise, bias-current error, and power. Tens of kilohms are common. Avoid extremely high values that amplify bias errors, and extremely low values that waste current.

What does the rectifier mode actually estimate?

It estimates the no-load peak after diode drops: Vrms×√2 − n×Vf. Real DC under load is lower due to ripple, transformer regulation, and diode heating. Use it for headroom budgeting, not ripple prediction.

What diode count should I enter?

For a bridge rectifier, current typically passes through two diodes, so enter 2. For a center-tap full-wave rectifier, conduction is usually one diode per half cycle, so enter 1.

What does the Plotly graph show?

It plots your saved session history and groups points by mode so you can compare configurations quickly. Export the underlying table with CSV, or generate a PDF report for sharing and documentation.