ST2-12B42 Equivalent & Substitute Parts

Part Overview

The ST2-12B42 is a laminated core power transformer manufactured by Pulse Electronics, rated at 1.1VA with a 115V primary voltage and dual secondary windings capable of 6.3V parallel or 12.6V series output. This through-hole mounted component is designed for applications requiring isolated AC power conversion with dual voltage flexibility. The part is Active status and RoHS Compliant, making it suitable for modern electronic equipment. Equivalent parts may be required due to supply constraints, regional availability, or design flexibility in component sourcing.

Substiute Parts

ST2-12B42

Pulse ElectronicsIn Stock: 1192ST2-12B42 Datasheet

Current PartRFQ

3FS-212

TamuraIn Stock: 24063FS-212 Datasheet

SimilarRFQ

ST-2-12

Signal TransformerIn Stock: 1651ST-2-12 Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the ST2-12B42 are qualified based on electrical and mechanical parameter equivalence. The substitution criteria are:

• Primary voltage: 115V (single winding)
• Secondary voltage configuration: Dual windings with 6.3V parallel and 12.6V series capability
• Output current ratings: 180mA parallel, 90mA series
• Power rating: 1.1VA
• Core type: Laminated
• Mounting: Through hole with PC pin termination
• Isolation voltage: 2500Vrms
• Compliance: RoHS Compliant status

The two qualified substitutes—3FS-212 (Tamura) and ST-2-12 (Signal Transformer)—meet all electrical specifications and core functional requirements. Dimensional variations exist but do not affect electrical performance or standard PCB mounting compatibility.

Parameter Comparison

Engineering Selection Recommendations

All three parts—ST2-12B42, 3FS-212, and ST-2-12—are Active status components with full electrical equivalence. Selection should be based on:

• Availability and inventory levels
• Packaging format requirements (Pulse: standard, Tamura: tube, Signal: box)
• PCB layout constraints due to dimensional differences
• Compliance certification alignment (ST-2-12 carries ROHS3 designation versus RoHS Compliant for the other two)
• Supply chain and lead time considerations

All parts carry REACH Unaffected status and EAR99 ECCN classification, meeting standard export and regulatory requirements.

Frequently Asked Questions (FAQ)

Q: Can 3FS-212 replace ST2-12B42 directly on the PCB? A: Electrically yes. The 3FS-212 meets all voltage, current, and power specifications. However, dimensional differences (35.56mm L × 31.00mm W versus 28.70mm L × 28.70mm W) require PCB layout verification to ensure clearance and mounting hole alignment.

Q: What is the difference between RoHS Compliant and ROHS3 Compliant? A: Both designations indicate compliance with RoHS directives. ROHS3 refers to the most recent RoHS 3 directive (2011/65/EU as amended). All three parts meet current RoHS requirements for this product category.

Q: Are there any electrical performance differences between the three parts? A: No. All three transformers provide identical electrical specifications: 1.1VA power rating, 115V primary, 6.3V/12.6V dual secondary, 180mA/90mA output current, and 2500Vrms isolation voltage.

Q: Which substitute should I choose for new designs? A: Selection depends on availability and packaging preference. All three are Active status with equivalent electrical performance. Verify PCB dimensions against your layout requirements before final selection.

Q: Is the weight difference significant? A: The ST2-12B42 and ST-2-12 both weigh 0.17 lb (77.11 g). The 3FS-212 weight is not specified. For most applications, this difference is negligible.