Elenco Electronics RS-500

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Summary

Resistance Substitution Box Components and Diagram

Schematic Diagram

Circuit diagram showing the internal wiring and component layout of the resistance substitution box.

Product Identification

Main title and model number (RS-500) of the resistance substitution box.

Manual Content

Introduction

Overview of the RS-500 Resistance Substitution Box and its intended use.

Operation

Instructions on how to select resistance values using the switches.

Two Year Warranty

Details on the warranty coverage and service procedures for Elenco products.

Parts List

List of resistors and miscellaneous components included with the RS-500.

Summary

Resistance Substitution Box Components and Diagram

Schematic Diagram

Circuit diagram showing the internal wiring and component layout of the resistance substitution box.

Product Identification

Main title and model number (RS-500) of the resistance substitution box.

Manual Content

Introduction

Overview of the RS-500 Resistance Substitution Box and its intended use.

Operation

Instructions on how to select resistance values using the switches.

Two Year Warranty

Details on the warranty coverage and service procedures for Elenco products.

Parts List

List of resistors and miscellaneous components included with the RS-500.

The Elenco RS-500 Resistance Substitution Box is a convenient and versatile instrument designed to assist in determining desired resistance values within electronic circuits, whether for design or testing purposes. It offers a broad range of resistance values, from 1 Ohm (Ω) up to 11,111,110 Ohms, adjustable in precise 1 Ohm steps. This wide range and fine granularity make it suitable for a multitude of applications in electronics development, troubleshooting, and education.

Function Description

At its core, the RS-500 operates on a simple yet effective principle: a series arrangement of resistors, each controlled by an individual switch. The device features 28 individual switches, each corresponding to a specific resistor value. When a switch is in the "OFF" (down) position, it effectively shorts out its associated resistor, meaning that resistor's value is not included in the total output resistance. Conversely, when a switch is moved to the "ON" (up) position, it removes the short, thereby placing its corresponding resistor in series with any other "ON" resistors across the output terminals.

To achieve a desired total resistance, the user simply activates the combination of switches whose individual resistor values sum up to the target resistance. For instance, to obtain a resistance of 5,071 Ohms, the user would turn on the switches corresponding to 3kΩ (3,000 Ohms), 2kΩ (2,000 Ohms), 40Ω, 30Ω, and 1Ω. The device's front panel is clearly laid out, with resistors grouped by their decade values (e.g., 1s, 10s, 100s, 1ks, 10ks, 100ks, 1Ms), making it intuitive to select the necessary components.

The output of the resistance substitution box is provided through two green binding posts located on the front panel. These posts serve as the connection points for the external circuit where the substituted resistance is needed. The "IN" and "OUT" labels next to the binding posts indicate the input and output connections for the substituted resistance.

Important Technical Specifications

Resistance Range: The RS-500 offers a comprehensive resistance range from 1Ω to 11,111,110Ω.
Step Size: Resistance values can be adjusted in precise 1Ω steps, allowing for fine-tuning and accurate selection.
Resistor Precision: All resistors incorporated within the RS-500 are precision 1% tolerance resistors. This ensures that the substituted resistance values are highly accurate, which is critical for sensitive circuit design and testing where component tolerances can significantly impact performance.
Power Rating: Each resistor in the RS-500 is rated for 1 Watt (W). This power rating indicates the maximum amount of power that each individual resistor can safely dissipate without damage. This is an important consideration when using the device in circuits that may draw significant current or have high voltage drops across the substituted resistance.
Number of Switches: The device features 28 individual DPDT (Double Pole Double Throw) slide switches, each controlling a specific resistor value.
Component List: The device is constructed with a PC Board (Part # 517011), 28 DPDT slide switches (Part # 541023), a front panel (Part # 614404), and a case (Part # 623004). Output connections are facilitated by two green binding posts (Part # 625033), secured with lockwashers (Part # 625031LW) and nuts (Part # 625031HN). The enclosure is assembled with 2mm x 17mm Philips screws (Part # 641103) and #4 external lockwashers (Part # 646405), and it stands on four rubber feet (Part # 662023) for stability and to prevent scratching surfaces.

The specific resistor values included are:

1Ω, 2Ω, 3Ω, 4Ω (1% 1W)
10Ω, 20Ω, 30Ω, 40Ω (1% 1W)
100Ω, 200Ω, 300Ω, 400Ω (1% 1W)
1KΩ, 2KΩ, 3KΩ, 4KΩ (1% 1W)
10KΩ, 20KΩ, 30KΩ, 40KΩ (1% 1W)
100KΩ, 200KΩ, 300KΩ, 400KΩ (1% 1/2W)
1MΩ, 2MΩ, 3MΩ, 4MΩ (1% 1/2W)

Note that resistors from 100KΩ to 4MΩ have a 1/2W power rating, while those from 1Ω to 40KΩ have a 1W power rating. This distinction is important for users to consider when operating the device in high-power circuits.

Usage Features

Ease of Use: The intuitive layout of the switches on the front panel, grouped by decade, simplifies the process of selecting the desired resistance. The clear labeling of each switch with its corresponding resistance value minimizes errors and speeds up the setup process.
Versatility: The wide range of resistance values and the fine 1Ω step size make the RS-500 suitable for a vast array of applications, from basic electronics experiments to complex circuit prototyping and troubleshooting. It can be used to determine optimal resistance values for biasing circuits, setting time constants, current limiting, voltage division, and many other circuit functions.
Durability: The device is housed in a robust case, designed to withstand the rigors of regular use in educational, hobbyist, and professional environments.
Compact Design: The physical dimensions of the unit are not explicitly stated, but typical substitution boxes are designed to be compact and easily portable, fitting well on a workbench or in a toolkit.

Maintenance Features

Two-Year Warranty: Elenco Electronics provides a comprehensive two-year warranty for the RS-500, covering all parts and service. For the first three months, any power supply issues are covered at no charge. For the remaining 21 months of the warranty period, a nominal service charge is required to cover shipping and handling costs. This warranty demonstrates the manufacturer's confidence in the product's quality and provides peace of mind for the user.
Repair Procedure: In the event that the device requires repair, Elenco outlines a clear procedure. Customers are instructed to include proof of purchase, a brief letter explaining the problem encountered, and sufficient packing material when returning merchandise. Before shipping, it is mandatory to call the service department at (847) 541-3800 to obtain a Return Merchandise Authorization (RMA) number. This structured approach helps ensure efficient and organized repair services.
Contact Information: Elenco Electronics, Inc. is located at 150 Carpenter Ave., Wheeling, IL 60090. They can be reached by phone at (847) 541-3800 or via email at elenco@elenco.com. Their website is elenco.com. This readily available contact information facilitates customer support and service requests.
Internal Construction: The schematic diagram provided in the manual illustrates the internal wiring of the resistors in series, with each resistor having a bypass switch. This design is robust and relatively easy to troubleshoot should an issue arise, although internal repairs are typically handled by qualified service personnel. The use of a PC board for component mounting contributes to reliability and ease of assembly.

The Elenco RS-500 Resistance Substitution Box is an indispensable tool for anyone involved in electronics, offering precision, versatility, and ease of use, backed by a solid warranty and support system.