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 RF Cascade Workbook 2018 RF Symbols for Visio - Word Advertising Magazine Sponsor RF Cafe RF Electronics Symbols for Visio RF Electronics Symbols for Office Word RF Electronics Stencils for Visio Sponsor Links Saturday Evening Post NEETS EW Radar Handbook Microwave Museum About RF Cafe Aegis Power Systems Anritsu Alliance Test Equipment Amplifier Solutions Anatech Electronics Axiom Test Equipment Berkeley Nucleonics Centric RF Conduct RF Copper Mountain Technologies Empower RF everything RF Exodus Advanced Communications Innovative Power Products ISOTEC KR Filters Lotus Systems PCB Directory Rigol San Francisco Circuits Reactel RFCT TotalTemp Technologies Triad RF Systems Windfreak Technologies Withwave LadyBug Technologies Wireless Telecom Group Sponsorship Rates RF Cafe Software Resources Vintage Magazines Thank you for visiting RF Cafe!

Resistor-Selection Nomogram
April 1967 Electronics World

April 1967 Electronics World

April 1967 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.

Even in the age of computers and smartphone applets for everything, some people still are not comfortable with mathematics, including something as relatively simple as Ohm's Law. There are still a lot of electronics tinkerers around who grew up in the pencil and paper era (like moi), where slide rules ruled the day. While a software program or electronics calculator is convenient for many uses, sometimes a printed graphical tool is easier to work with - at least in a lab environment. Accordingly, for those who still appreciate a good resistor selection nomograph, here is one from the April 1967 edition of Electronics World magazine.

Here's a challenge for recent college grads that are scoffing at the old guys who are right now having a grandkid print out a copy of this nomograph for them: What is the resistor color code number associated with the color of the nomograph (green)?

Resistor-Selection Nomogram

Resistor-Selection Nomogram, April 1967 Electronics World - RF Cafe

Resistor-Selection Nomogram

By Sylvester Salva

Resistance values and power dissipations may be readily determined by the use of a straightedge.

For the man involved in the electronics field, it frequently becomes necessary to determine the value of a resistor and wattage. The nomogram below was designed to give the resistor value and its wattage simply by placing a straightedge from the potential scale to the proper current scale and reading the answer on the Resistor Value Scale or the Wattage Scale.

It will be noted that there are two current scales on the nomogram. They are listed as Current (Milliamps) Scale No. 1 and Current (Milliamps) Scale No.2. Scale No.1 is used only when determining the value of the resistor. Scale No. 2 is used for determining the wattage of the resistor.

Following are two examples illustrating the use of the nomogram.

Example No.1: It is found that a cathode bias resistor is burned out and no schematic is available. Total current of the tube - rated at 60 mA. Grid bias is -18 volts. Determine the value, in ohms, and wattage of the resistor.

Solution: Extend a straight line from 18 on the Potential Scale to 60 on the Current Sca1e No. 1. Read the value of the resistor at the intersection of this line with the Resistor Value Scale as 300 ohms. To determine the wattage, extend another line from 18 on the Potential Scale to 60 on the Current Scale No. 2. At the intersection of this line with the wattage scale, read the answer as slightly over 1 watt. Since the value is higher than 1, use the next higher value, namely 2 watts.

Example No.2: Determine the value, in ohms, and wattage of a resistor under the following conditions: Voltage is measured at 117 volts, current at 10 mA.

Solution: Extend a straight line from 117 on the Potential Scale to 10 on the Current Scale No. 1. At the intersection of this line with the Resistor Value Scale read the value as 11.7 kohms. To determine the wattage, extend another line from 117 on the Potential Scale to 10 on the Current Scale No.2. At the intersection of this line with the Resistor Wattage Scale, read the answer as just over 1 watt. Assigning the next highest value, the answer then becomes 2 watts.

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 July 13, 2021
(updated from original post on 3/18/2012)

RF Electronics Shapes, Stencils for Office, Visio by RF Cafe
Lotus Communication Systems Modular RF Component Building Blocks - RF Cafe
Berkeley Nucleonics Vector Signal Generators Radar Simulations - RF Cafe
TotalTemp Technologies (Thermal Platforms) - RF Cafe
Amplifier Solutions Corporation (ASC) - RF Cafe

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

These Are Available for Free


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...

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: