Electronics World articles Popular Electronics articles QST articles Radio & TV News articles Radio-Craft articles Radio-Electronics articles Short Wave Craft articles Wireless World articles Google Search of RF Cafe website Sitemap Electronics Equations Mathematics Equations Equations physics Manufacturers & distributors Engineer Jobs LinkedIn Crosswords Engineering Humor Kirt's Cogitations RF Engineering Quizzes Notable Quotes Calculators Education Engineering Magazine Articles Engineering software RF Cafe Archives Advertising Magazine Sponsor RF Cafe Sponsor Links Saturday Evening Post NEETS EW Radar Handbook Microwave Museum About RF Cafe Aegis Power Systems Alliance Test Equipment Centric RF Empower RF ISOTEC Reactel RF Connector Technology San Francisco Circuits Anritsu Amplifier Solutions Anatech Electronics Axiom Test Equipment Berkeley Nucleonics Conduct RF Copper Mountain Technologies everything RF Exodus Advanced Communications Innovative Power Products KR Filters LadyBug Technologies Lotus Systems PCB Directory Rigol Temwell RF Components TotalTemp Technologies Werbel Microwave Windfreak Technologies Wireless Telecom Group Withwave Sponsorship Rates RF Cafe Software Resources Vintage Magazines RF Cafe Software RF Cafe Sponsor Links WhoIs entry for RF Cafe.com Thank you for visiting RF Cafe!

KR Electronics (RF Filters) - RF Cafe

Please Support RF Cafe by purchasing my  ridiculously low−priced products, all of which I created.

RF Cascade Workbook for Excel

RF & Electronics Symbols for Visio

RF & Electronics Symbols for Office

RF & Electronics Stencils for Visio

RF Workbench  (shareware)

T-Shirts, Mugs, Cups, Ball Caps, Mouse Pads

These Are Available for Free

Espresso Engineering Workbook™

Smith Chart™ for Excel

RF Cascade Workbook 2018 - RF Cafe

Versatile Voltage, Power, and Decibel Nomograms
August 1962 Electronics World

August 1962 Electronics World

August 1962 Electronics World Cover - RF Cafe  Table of Contents 

Wax nostalgic about and learn from the history of early electronics. See articles from Electronics World, published May 1959 - December 1971. All copyrights hereby acknowledged.

August 1962 was a good month for lovers of nomographs and infographics. Electronics World magazine published three articles feeding the mania, including this one, Sound | Audio | Music Infographic, and Coil-Winding Charts. All make good printed references to keep on-hand. One nomograph converts the ratio of two power levels (in watts, milliwatts, etc.) to equivalent decibels of gain. It can also be used to find the unknown power level if one is known and the gain in dB is known. The other nomograph facilitates graphically calculating voltage or power based on the source resistance (assumed to have only real components; i.e., no complex values). If you are not sure how to keep units constant for voltage, power, and resistance (milli, micro, etc.), calculate using the base units and then convert afterward.

Versatile Voltage, Power, and Decibel Nomograms

By Jim Kyle

Power ratio to decibel conversion nomograph - RF Cafe

Chart 1 - Voltage to power conversion nomograph.

Two useful charts that enable the audio technician to find amplifier gains and losses even when voltage measurements are taken across different impedances.

Calculations of power levels and decibel ratios from voltage readings often lead to confusion for both experienced technicians and beginners, since the conventional formula for determining decibel ratio from voltage readings assumes that each reading is taken at the same impedance level.

Many charts, tables, and graphs have been published to aid in solving such problems. However, the charts shown here offer features not to be found in such previous aids. With them, power corresponding to any voltage reading can be determined if resistance is known, voltage can be determined if power is known, and the gain or loss in decibels of any equipment can be determined if input and output voltages and resistance can be measured.

ower ratio to decibels conversion nomograph - RF Cafe

Chart 2 - Power (watts) ratio to decibels conversion nomograph.

Chart 1 is used for voltage-power-resistance calculations. Chart 2 converts power levels directly to decibels gain or loss.

The voltage and resistance scales of Chart 1 bear two sets of graduations, labeled E1 and R1 and E2 and R2 respectively. Scales bearing the same suffix number are used together.

For example, suppose an amplifier is under test. A 10-volt signal applied to the 500-ohm input produces an output measured at 5 volts across 8 ohms.

First, determine input power from Chart 1. The line connecting 10 volts (E2 scale) and 500 ohms (R2 scale) passes through 0.2 watt. Output power is next. This time, the E1 and R1 scales of Chart 1 are used, yielding an answer of 3.1 watts.

Now we turn to Chart 2. Connecting the 3.1-watt output (PI scale) and the 0.2-watt input (P2 scale) gives a total amplifier gain of just under 12 decibels.

Nomographs / Nomograms Available on RF Cafe:

- Parallel Series Resistance Calculator

- Transformer Turns Ratio Nomogram

- Symmetrical T and H Attenuator Nomograph

- Amplifier Gain Nomograph

- Decibel Nomograph

- Voltage and Power Level Nomograph

- Nomograph Construction

- Nomogram Construction for Charts with Complicating Factors or Constants

- Link Coupling Nomogram

- Multi-Layer Coil Nomograph

- Delay Line Nomogram

- Voltage, Current, Resistance, and Power Nomograph

- Resistor Selection Nomogram

- Resistance and Capacitance Nomograph

- Capacitance Nomograph

- Earth Curvature Nomograph

- Coil Winding Nomogram

- RC Time-Constant Nomogram

- Coil Design Nomograph

- Voltage, Power, and Decibel Nomograph

- Coil Inductance Nomograph

- Antenna Gain Nomograph

- Resistance and Reactance Nomograph

- Frequency / Reactance Nomograph



Posted June 21, 2021
Exodus Advanced Communications Best in Class RF Amplifier SSPAs - RF Cafe

About RF Cafe

Kirt Blattenberger - RF Cafe Webmaster

Copyright: 1996 - 2024


    Kirt Blattenberger,


RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling 2 MB. Its primary purpose was to provide me with ready access to commonly needed formulas and reference material while performing my work as an RF system and circuit design engineer. The World Wide Web (Internet) was largely an unknown entity at the time and bandwidth was a scarce commodity. Dial-up modems blazed along at 14.4 kbps while tying up your telephone line, and a nice lady's voice announced "You've Got Mail" when a new message arrived...

Copyright  1996 - 2026

All trademarks, copyrights, patents, and other rights of ownership to images and text used on the RF Cafe website are hereby acknowledged.

All trademarks, copyrights, patents, and other rights of ownership to images and text used on the RF Cafe website are hereby acknowledged.

My Hobby Website:


Innovative Power Products Passive RF Products - RF Cafe

Rigol DHO1000 Oscilloscope - RF Cafe