Honeywell 309NPC50K Potentiometer: Equivalent & Substitute Parts

Part Overview

The Honeywell 309NPC50K is a 50k Ohm, 1 Watt panel mount potentiometer featuring a cermet resistive element, linear taper, and single-turn operation. This component is classified as obsolete, necessitating identification of active substitute parts for ongoing applications and new designs. The 309NPC series represents a legacy potentiometer platform; equivalent alternatives must maintain functional compatibility across resistance value, power rating, mechanical mounting, and electrical performance parameters.

Substiute Parts

309NPC50K

Honeywell Sensing and Productivity SolutionsIn Stock: 800309NPC50K Datasheet

Current PartRFQ

51CAD-E24-B18L

Bourns Inc.In Stock: 96551CAD-E24-B18L Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitute identification for the 309NPC50K is based on strict parameter matching across the following criteria:

Mandatory Matching Parameters:

• Resistance: 50k Ohm (exact match required)
• Taper: Linear (functional requirement)
• Number of Turns: 1 (operational specification)
• Mounting Type: Panel Mount with 1/4-32 bushing thread (mechanical interface)
• Termination Style: PC Pins (electrical connection)
• Adjustment Type: Side Adjustment (operational interface)

Allowable Variations:

• Power Rating: Substitute must equal or exceed 1W minimum
• Tolerance: Substitute tolerance may differ from ±10%
• Resistive Material: Cermet or Conductive Plastic acceptable
• Body Size: Minor dimensional variations acceptable if mounting interface remains compatible
• Product Status: Active status preferred for long-term availability

The Bourns 51CAD-E24-B18L meets all mandatory matching parameters while providing equivalent functional performance in applications requiring 50k Ohm linear potentiometer operation.

Parameter Comparison

Engineering Selection Recommendations

Primary Consideration: Product Status

The Honeywell 309NPC50K is classified as obsolete. The Bourns 51CAD-E24-B18L carries active product status, ensuring continued availability, manufacturing support, and compliance with current regulatory standards.

Compliance and Certification

Both components meet RoHS requirements. The Bourns substitute carries ROHS3 compliance and is REACH Affected, aligning with current European regulatory frameworks. The Honeywell part is RoHS Compliant under earlier standards.

Functional Equivalence

The 51CAD-E24-B18L provides functional equivalence for 50k Ohm linear potentiometer applications. Mandatory parameters—resistance value, taper, number of turns, mounting interface, and termination style—are identical. The substitute maintains mechanical compatibility through matching bushing thread (1/4-32), actuator dimensions, and side adjustment configuration.

Parameter Deviations Requiring Evaluation

Power Rating: The Bourns substitute is rated at 0.5W versus the original 1W specification. Applications requiring continuous operation at maximum power dissipation must verify that 0.5W rating is sufficient for the intended duty cycle.

Resistive Material: The substitute uses conductive plastic instead of cermet. This material change may affect frequency response, noise characteristics, and long-term stability in specific applications. Conductive plastic elements typically exhibit lower noise but may have different temperature coefficient behavior.

Tolerance: The substitute carries ±20% tolerance versus ±10% for the original. Applications requiring tighter resistance tolerance must account for this specification difference.

Body Dimensions: Minor dimensional variations exist (rectangular versus square profile). Panel cutout compatibility must be verified for existing mechanical designs.

Recommendation Basis

Selection of the Bourns 51CAD-E24-B18L as a substitute is based on:

• Exact match of critical electrical parameters (50k Ohm, linear, single-turn)
• Identical mechanical mounting interface (1/4-32 panel mount)
• Matching termination and adjustment specifications
• Active product status ensuring supply continuity
• Current regulatory compliance (ROHS3, REACH)

Frequently Asked Questions (FAQ)

Q: Can the Bourns 51CAD-E24-B18L directly replace the Honeywell 309NPC50K in existing designs?

A: Direct mechanical and electrical replacement is possible for most applications. The substitute maintains identical mounting interface (1/4-32 bushing thread), actuator dimensions, and PC pin termination. However, verify that the 0.5W power rating is adequate for your application's duty cycle, and confirm that the ±20% tolerance meets your circuit requirements.

Q: What is the significance of the resistive material difference (Cermet vs. Conductive Plastic)?

A: Cermet elements typically provide higher power handling and greater stability over temperature extremes. Conductive plastic elements generally exhibit lower noise and smoother operation. The material change may affect noise floor, frequency response, and temperature coefficient behavior. Evaluate these characteristics against your application's performance requirements.

Q: Are there mechanical compatibility issues with the body size difference?

A: The Bourns substitute has a rectangular body (0.521" x 0.492") versus the square body (0.500" x 0.500") of the original. If your panel cutout is precisely sized for the square profile, the rectangular substitute may not fit. Verify panel cutout dimensions before implementation.

Q: Does the lower power rating (0.5W vs. 1W) affect functionality?

A: Power rating determines maximum continuous dissipation capability. If your application operates the potentiometer at continuous power levels below 0.5W, the substitute is functionally equivalent. Applications requiring sustained operation above 0.5W dissipation must use a higher-rated component.

Q: How do the tolerance specifications compare?

A: The original 309NPC50K carries ±10% tolerance; the Bourns substitute carries ±20%. For applications requiring precise resistance values, the wider tolerance of the substitute may introduce greater circuit variation. Verify that your circuit design accommodates ±20% resistance variation.

Q: Are both components RoHS compliant?

A: Yes. The Honeywell 309NPC50K is RoHS Compliant. The Bourns 51CAD-E24-B18L is ROHS3 Compliant, representing current regulatory standards. Both components meet RoHS requirements for new designs and manufacturing.

Q: What is the inventory status for these components?

A: The Honeywell 309NPC50K has 760 pieces in stock (obsolete status). The Bourns 51CAD-E24-B18L has 916 pieces in stock with active product status, ensuring continued availability and manufacturing support.

Q: Are there differences in rotation angle?

A: The Honeywell component specifies 295° rotation; the Bourns substitute specifies 290°. This 5° difference is minor and does not affect functional operation in standard potentiometer applications. Both components provide single-turn operation with mechanical stops.

Q: What temperature coefficient specification applies to the substitute?

A: The Bourns 51CAD-E24-B18L specifies ±1000ppm/°C temperature coefficient. The original Honeywell specification does not provide this parameter. For applications operating across wide temperature ranges, verify that ±1000ppm/°C meets your circuit's temperature stability requirements.