Grayhill 78B12 DIP Switch - Equivalent & Substitute Parts

Part Overview

The Grayhill 78B12 is a 12-position SPST slide DIP switch rated for 150mA at 30VDC with through-hole mounting and PC pin termination. This component is classified as obsolete, making equivalent substitutes necessary for new designs and ongoing production support. The 78B12 features a raised slide actuator, gold-plated copper alloy contacts, and operates across -40°C to 85°C with 2,000 mechanical and electrical life cycles.

Substiute Parts

78B12

Grayhill Inc.In Stock: 94978B12 Datasheet

Current PartRFQ

78B12T

Grayhill Inc.In Stock: 117578B12T Datasheet

DirectRFQ

BD12

C&KIn Stock: 2032BD12 Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the 78B12 is determined by strict electrical and mechanical parameter matching. The following criteria establish valid substitutes:

Primary Substitution Criteria:

• Circuit configuration must be SPST
• Number of positions must be 12
• Mounting type must be through hole
• Termination style must be PC pin
• Pitch must be 0.100" (2.54mm)
• Operating temperature range must encompass -40°C to 85°C
• Actuator type must be slide (standard) with raised level

Electrical Compatibility Criteria:

• Current rating must equal or exceed 150mA
• Voltage rating must equal or exceed 30VDC

Mechanical Compatibility Criteria:

• Height above board and length must be within acceptable PCB layout tolerances
• Contact material and finish must support equivalent electrical performance

The 78B12 has two identified substitutes: the Grayhill 78B12T and the C&K BD12. The 78B12T is a direct manufacturer equivalent with identical electrical and mechanical specifications but improved product status and RoHS compliance. The BD12 is a cross-manufacturer substitute from C&K with compatible form factor and function but with reduced electrical ratings and enhanced mechanical durability.

Parameter Comparison

Engineering Selection Recommendations

Grayhill 78B12T (Preferred Primary Substitute)

The 78B12T is the recommended substitute for new designs and production transitions. This part maintains identical electrical specifications (150mA, 30VDC) and mechanical form factor as the obsolete 78B12. The 78B12T carries active product status with ROHS3 compliance, ensuring long-term availability and regulatory alignment. Packaging in tube format supports automated assembly processes. No design modifications are required for direct substitution.

C&K BD12 (Application-Dependent Substitute)

The BD12 is suitable only for applications where the reduced electrical ratings (100mA at 5VDC) are compatible with circuit requirements. This part offers enhanced mechanical durability with 10,000 cycle life versus 2,000 cycles for the 78B12. The BD12 features phosphor bronze contacts and glass-filled PBT body material, providing improved washability and environmental resistance. Height above board is 0.297" versus 0.315" for the 78B12, requiring PCB layout verification. The BD12 is appropriate for low-voltage logic-level switching applications only.

Compliance Considerations

Both substitute parts achieve ROHS3 compliance and REACH unaffected status, supporting modern regulatory requirements. The obsolete 78B12 is RoHS non-compliant and should be phased out in favor of compliant alternatives.

Frequently Asked Questions (FAQ)

Q: Can the 78B12T be used as a direct drop-in replacement for the 78B12?

A: Yes. The 78B12T maintains identical electrical ratings (150mA, 30VDC), mechanical dimensions (0.315" height, 1.280" length), and pin configuration (0.100" pitch, PC pin termination). No circuit modifications are required. The primary difference is product status (active versus obsolete) and RoHS compliance.

Q: What are the limitations of the C&K BD12 as a substitute?

A: The BD12 has reduced electrical ratings: 100mA maximum current and 5VDC maximum voltage. It is suitable only for applications operating within these limits. The BD12 height above board is 0.297" compared to 0.315" for the 78B12, requiring PCB layout verification to ensure clearance compatibility. The BD12 is not suitable for 30VDC applications.

Q: Are there packaging differences between the 78B12 and 78B12T?

A: Yes. The 78B12 is supplied in bulk packaging, while the 78B12T is supplied in tube packaging. Tube packaging supports automated pick-and-place assembly and provides improved component protection during handling and storage.

Q: What is the mechanical life difference between the 78B12 and BD12?

A: The 78B12 and 78B12T are rated for 2,000 mechanical cycles, while the BD12 is rated for 10,000 mechanical cycles. The BD12's enhanced durability results from phosphor bronze contacts and glass-filled PBT body material. For applications requiring extended switch life, the BD12 offers superior longevity within its electrical rating constraints.

Q: Are all three parts RoHS compliant?

A: No. The 78B12 is RoHS non-compliant. Both the 78B12T and BD12 are ROHS3 compliant. For new designs and regulatory compliance, the 78B12T or BD12 must be selected.

Q: Can the BD12 be used in 30VDC circuits?

A: No. The BD12 is rated for 5VDC maximum. Using the BD12 in 30VDC circuits exceeds its voltage rating and will result in component failure or safety hazards. The 78B12T must be used for 30VDC applications.

Q: What is the contact material difference between the 78B12 and BD12?

A: The 78B12 uses copper alloy contacts, while the BD12 uses phosphor bronze contacts. Both materials are gold-plated. Phosphor bronze provides superior corrosion resistance and mechanical durability, contributing to the BD12's extended cycle life rating.