---
title: "Remote control or digital multimeter"
subject: "Basic Electronics Engineering"
chapter: 7
key: "semester_2/basic_electronics_engineering:remote-control-or-dmm"
source: https://www.bctengineer.com/q/semester_2/basic_electronics_engineering/remote-control-or-dmm
site: BCT Engineering
---

# Remote control or digital multimeter

Basic Electronics Engineering · Chapter 7: Application of Electronic System

- Asked in: 2071 Magh, 4 marks
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_2/basic_electronics_engineering/remote-control-or-dmm
- Whole chapter: https://www.bctengineer.com/md/semester_2/basic_electronics_engineering/chapter-7

## Question

Explain briefly about remote control or digital multimeter with necessary diagrams.

## Short answer

A digital multimeter measures voltage, current, and resistance by converting each to a small DC voltage via a range selector (attenuator, shunt, or constant current source). After signal conditioning, an ADC digitizes the voltage, and a decoder drives the LCD display, providing high accuracy and auto-polarity.

## Answer

The question allows a choice; the digital multimeter is explained here.

A **digital multimeter** measures voltage, current and resistance and shows the result as digits on an LCD or LED display.

#### Block diagram

```text
 Input -> Range      -> Signal     -> ADC -> Decoder/ -> Display
          selector      conditioner         driver
          (atten.,       (amp, AC/DC)
           shunt)
             ^                         ^
             +--- Control logic, clock, reference ---+
```

#### Working

1. **Range selector:** attenuator for voltage, shunt resistor for current, and constant current source for resistance; this converts every measured quantity into a small DC voltage.
2. **Signal conditioner:** amplifies the voltage; for AC, a rectifier converts AC to DC (RMS converter).
3. **ADC:** converts the DC voltage to a digital number (dual-slope ADC is common, giving good noise rejection).
4. **Decoder and driver:** convert the digital number to the seven-segment code and drive the display.
5. **Control logic and clock:** provide the timing and the reference voltage.

Features: high accuracy, input impedance of about 10 MΩ, auto-polarity and auto-range, no parallax error. Also, it can test diodes and continuity.

## Check yourself

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

1. What is the role of the range selector in the DMM?
   A. It displays the digits
   B. Attenuator, shunt or constant current source converts each quantity into a small DC voltage
   C. It stores the readings
   D. It generates the clock
   Answer: B. Attenuator (voltage), shunt (current) and constant current source (resistance) all produce a small DC voltage for the ADC. (Key point: Range selector function)

2. How is an AC input handled?
   A. Fed directly to the ADC
   B. Blocked by the range selector
   C. A rectifier or RMS converter in the conditioner changes it to DC
   D. Converted by the decoder
   Answer: C. The signal conditioner includes an AC-to-DC (RMS) converter before the ADC. (Key point: AC measurement)

3. What do the decoder and driver do?
   A. Convert the digital number to seven-segment code and drive the display
   B. Convert analog to digital
   C. Amplify the input
   D. Set the range
   Answer: A. They translate the ADC's digital output into seven-segment form for the display. (Key point: Decoder and driver)

## Related in Basic Electronics Engineering

- [Data logger and remote control block diagrams](https://www.bctengineer.com/question.md?key=semester_2%2Fbasic_electronics_engineering%3Adata-logger-remote-control) — Basic Electronics Engineering, chapter 7
- [Short note: Digital multimeter (DMM)](https://www.bctengineer.com/question.md?key=semester_2%2Fbasic_electronics_engineering%3Ashort-note-dmm) — Basic Electronics Engineering, chapter 7, asked 4×

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