Equivalent & Substitute Parts for Grayhill 78C04RAT DIP Switch

Part Overview

The Grayhill 78C04RAT is a 4-position DIP switch with SPST circuit configuration, rated for 25mA at 24VDC, featuring a slide actuator and through-hole right-angle mounting. This component is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and procurement continuity. The 78C04RAT remains in stock inventory (727 pcs), but alternative solutions are available from both the original manufacturer and cross-compatible suppliers to ensure long-term component availability and design flexibility.

Substiute Parts

78C04RAT

Grayhill Inc.In Stock: 80478C04RAT Datasheet

Current PartRFQ

78B04RAT

Grayhill Inc.In Stock: 112978B04RAT Datasheet

DirectRFQ

KAS2104E

E-SwitchIn Stock: 6089KAS2104E Datasheet

SimilarRFQ

KAS2104ET

E-SwitchIn Stock: 2689KAS2104ET Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution logic for the 78C04RAT is based on the following allowed parameters:

Direct Electrical Compatibility: All substitute parts maintain SPST circuit topology with 4-position configuration. Current and voltage ratings must equal or exceed the original specification (25mA, 24VDC).

Mechanical Compatibility: Mounting type (through-hole, right-angle), pitch (0.100"), and actuator type (slide, standard, raised) must remain identical to ensure PCB footprint compatibility and user interface consistency.

Physical Envelope: Height above board and overall length are critical for clearance in confined spaces. Substitutes with equivalent or lower profile dimensions are acceptable.

Contact Material and Finish: Phosphor bronze with gold finish is the baseline specification. Copper alloy with gold finish (as in the 78B04RAT) represents an acceptable alternative with enhanced electrical performance characteristics.

Compliance and Lifecycle: RoHS3 compliance and active product status are preferred for long-term availability and regulatory alignment.

Parameter Comparison

Engineering Selection Recommendations

For Direct Replacement (Electrical and Mechanical Equivalence):

The KAS2104E and KAS2104ET from E-Switch provide direct functional equivalence to the 78C04RAT. Both parts maintain identical electrical ratings (25mA, 24VDC), circuit configuration (SPST, 4-position), and mechanical interface (through-hole, right-angle, 0.100" pitch, 0.390" height). These parts are active products with ROHS3 compliance, ensuring long-term availability and regulatory alignment. The KAS2104ET variant includes tape seal washability, providing enhanced protection for moisture-sensitive applications.

For Enhanced Performance (Higher Electrical Ratings):

The Grayhill 78B04RAT offers superior electrical performance with 150mA current capacity and 30VDC voltage rating, along with extended electrical life (10,000 cycles versus 2,000 cycles). This part is suitable for applications requiring higher switching capacity while maintaining mechanical compatibility. The 78B04RAT is an active product with ROHS3 compliance. Height above board is 0.380" (9.64mm), which is 0.010" lower than the original specification, providing improved clearance in space-constrained designs.

Compliance Considerations:

All substitute parts carry ROHS3 compliance and REACH unaffected status, meeting current regulatory requirements. The 78C04RAT carries RoHS compliance (non-ROHS3), while all substitutes are ROHS3 compliant, representing an upgrade in regulatory alignment.

Temperature Operating Range:

The 78C04RAT operates from -20°C to 70°C. All substitute parts extend this range to -40°C to 85°C, providing enhanced thermal performance for demanding environments.

Frequently Asked Questions (FAQ)

Q: Can the KAS2104E replace the 78C04RAT in my existing PCB design?

A: Yes. The KAS2104E maintains identical electrical specifications (25mA, 24VDC, SPST, 4-position), actuator type (slide, standard, raised), mounting configuration (through-hole, right-angle), and pitch (0.100"). Height above board is identical at 0.390". No PCB redesign is required.

Q: What is the difference between KAS2104E and KAS2104ET?

A: Both parts are electrically and mechanically identical. The KAS2104ET includes tape seal washability, making it suitable for applications requiring moisture protection during assembly or cleaning processes. The KAS2104E is not washable. Both are packaged in tubes and carry ROHS3 compliance.

Q: Why would I choose the 78B04RAT over the KAS2104E?

A: The 78B04RAT provides higher electrical capacity (150mA versus 25mA) and extended electrical life (10,000 cycles versus 2,000 cycles). If your application requires higher switching current or longer operational life, the 78B04RAT is the appropriate selection. Mechanical compatibility remains identical. The 78B04RAT is also a Grayhill product, maintaining manufacturer consistency if preferred.

Q: Are there any height clearance differences between these parts?

A: The 78C04RAT and KAS2104E/KAS2104ET both measure 0.390" above board. The 78B04RAT measures 0.380", providing 0.010" additional clearance. All three parts fit within the same mechanical envelope for standard applications.

Q: What is the contact material difference between the 78C04RAT and 78B04RAT?

A: The 78C04RAT uses phosphor bronze contacts, while the 78B04RAT uses copper alloy contacts. Both are finished with gold plating. Copper alloy provides enhanced electrical conductivity and is suitable for higher current applications. For the 25mA rating of the 78C04RAT, either material is acceptable.

Q: Are all substitute parts RoHS compliant?

A: Yes. The 78C04RAT carries RoHS compliance. All substitute parts (78B04RAT, KAS2104E, KAS2104ET) carry ROHS3 compliance, which represents a higher regulatory standard and ensures compatibility with current manufacturing requirements.

Q: What is the mechanical life rating for these switches?

A: All parts listed (78C04RAT, 78B04RAT, KAS2104E, KAS2104ET) have a mechanical life rating of 2,000 cycles. The 78B04RAT extends electrical life to 10,000 cycles, but mechanical life remains 2,000 cycles across all models.

Q: Can I use these switches in applications below 24VDC?

A: Yes. All parts are rated for 24VDC operation and can be used at lower voltages. The 78B04RAT is rated for 30VDC, providing additional voltage margin. Verify that your application current does not exceed the part's current rating (25mA for 78C04RAT, KAS2104E, KAS2104ET; 150mA for 78B04RAT).