---
title: "Clamper adding +5 V DC level"
subject: "Basic Electronics Engineering"
chapter: 2
key: "semester_2/basic_electronics_engineering:clamper-adds-5v"
source: https://www.bctengineer.com/q/semester_2/basic_electronics_engineering/clamper-adds-5v
site: BCT Engineering
---

# Clamper adding +5 V DC level

Basic Electronics Engineering · Chapter 2: Diodes

- Asked in: 2072 Magh, 1+3 marks
- Video: [Biased Clamper Circuit](https://www.youtube.com/watch?v=kLRuU3VcXPA) — Neso Academy
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_2/basic_electronics_engineering/clamper-adds-5v
- Whole chapter: https://www.bctengineer.com/md/semester_2/basic_electronics_engineering/chapter-2

## Question

What is a clamper circuit? Draw the clamper circuit that adds +5 volts DC level on AC voltage.

## Short answer

A clamper shifts an AC waveform by adding a DC level. To add +5 V, use a biased positive clamper with a 5 V battery in series with the diode (anode to battery positive, cathode to output). The capacitor charges to Vm+5 V, and output becomes Vin+Vm+5, with negative peak clamped at +5 V.

## Answer

A **clamper circuit** (dc restorer) is a circuit that shifts an ac waveform up or down by adding a dc level to it, without changing the waveform's shape. It is made of a capacitor, a diode, a resistor and, when needed, a dc battery.

#### Clamper that adds +5 V
**Assumption:** "adds +5 V" is taken to mean that the negative peak of the output is clamped at +5 V (ideal diode), so the whole waveform is moved upward.

```text
                C
 Vin o---------| |--------+--------+---o Vout
                          |        |
                        -----      |
                         / \   D   R
                        /___\      |
                          |        |
                        + |        |
                        -----      |
                         ---  5 V  |
                        - |        |
 GND o--------------------+--------+---o
```
The diode anode connects to the positive terminal of the 5 V battery (battery negative to ground) and its cathode to the output node. The resistor R is across the output.

**Working** (Vin = Vm sin ωt, ideal diode)
- The diode turns ON whenever Vout tries to go below +5 V. In the first negative half cycle, the capacitor charges to Vc = Vm + 5 V.
- Afterwards the diode is OFF and the capacitor holds this voltage (RC ≫ T).
- Output: Vout = Vin + (Vm + 5)

For example, for Vm = 10 V, Vc = 15 V and Vout ranges from +5 V to +25 V.

If the aim is to add exactly a +5 V dc component to the signal (mean level = +5 V, i.e. Vout = Vin + 5), the battery value should be 5 − Vm (a negative value, i.e. a reversed battery, when Vm > 5 V).

For a real silicon diode, the clamped level is reduced by 0.7 V.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. In the circuit with a 5 V battery, at what level is the output negative peak clamped?
   A. 0 V
   B. -5 V
   C. +5 V
   D. +10 V
   Answer: C. The diode turns on when Vout tries to go below +5 V. (Key point: Clamping level)

2. For Vm = 10 V, to what voltage does the capacitor charge?
   A. 5 V
   B. 10 V
   C. 25 V
   D. 15 V
   Answer: D. Vc = Vm + 5 V = 15 V. (Key point: Capacitor voltage)

3. For Vm = 10 V, what is the output range?
   A. +5 V to +25 V
   B. 0 V to +20 V
   C. -5 V to +15 V
   D. +5 V to +15 V
   Answer: A. Vout = Vin + 15 V gives 5 V to 25 V. (Key point: Output range)

## Related in Basic Electronics Engineering

- [Diode clamper circuit operation](https://www.bctengineer.com/question.md?key=semester_2%2Fbasic_electronics_engineering%3Adiode-clamper-operation) — Basic Electronics Engineering, chapter 2
- [Short note: Diode clamper circuit](https://www.bctengineer.com/question.md?key=semester_2%2Fbasic_electronics_engineering%3Ashort-note-diode-clamper) — Basic Electronics Engineering, chapter 2
- [Voltage divider bias, DC load line, Q point (20 V)](https://www.bctengineer.com/question.md?key=semester_2%2Fbasic_electronics_engineering%3Avoltage-divider-bias-20v) — Basic Electronics Engineering, chapter 3, asked 2×
- [Voltage divider bias, DC load line, Q point (15 V)](https://www.bctengineer.com/question.md?key=semester_2%2Fbasic_electronics_engineering%3Avoltage-divider-bias-15v) — Basic Electronics Engineering, chapter 3, asked 2×
- [What are clipper and clamper circuits](https://www.bctengineer.com/question.md?key=semester_2%2Fbasic_electronics_engineering%3Aclipper-clamper-define) — Basic Electronics Engineering, chapter 2
- [Design clamper for given waveforms](https://www.bctengineer.com/question.md?key=semester_2%2Fbasic_electronics_engineering%3Aclamper-20v-to-30v) — Basic Electronics Engineering, chapter 2

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- [Clamper circuit output waveform](https://www.bctengineer.com/question.md?key=semester_1%2Ffundamental_of_electrical_and_electronics_engineering%3Aclamper-output-waveform) — Fundamental of Electrical and Electronics Engineering, chapter 4
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