Bobbin Wound Transformers


Application Notes > Custom Transformers > Bobbin Wound Transformers

Gowanda designs and manufactures Bobbin Wound Transformers for a variety of power supply and power conversion applications. Bobbin wound transformers may be designed in a wide variety of shapes and sizes.

A Bobbin Wound Transformer is a transformer that is designed with the coil wound on a coil form or bobbin. The core structure is then mounted to the bobbin. Bobbin wound transformers can be designed to operate from 60Hz, or line frequency, well into the MHz range.

Bobbin Wound Transformer Applications
      • Switch mode power supplies
      • Power conversion applications
      • Circuit isolation applications
      • Filter circuits
      • Any application that the transformer can be designed on a bobbin or coil form
      • Design upper limits of a Power Transformer
Bobbin Wound Transformer Design
      • Power rating in VA
      • Operating frequency in Hz
      • Number of primary windings
      • Number of secondary windings
      • Operating voltages levels
      • Operating current levels
      • Operating frequency is needed for core calculations and wire sizing
      • Core material is selected for the known operating frequency or frequencies which can be anything from silicon steel laminations to a ferrite core structure
      • Other bobbin wound transformer design considerations are space limitations and mounting technique
      • Lead terminations, if needed, may also be specified through the design of a Bobbin Wound Transformer

Bobbin wound transformer designs vary widely in terms of power rating, voltage and current levels (turns ratios), operating frequency, size, impedance, bandwidth (frequency response), packaging, winding capacitance, and other parameters.

Photo Gallery

This Bobbin Wound Power Transformer was built to mount on a chassis panel.

      • Input Voltage: Dual Primary (2 x 115V)@60Hz
      • Output Voltage: 2 x 80V @ 1A, CT. w/ CenterTap Windings
      • Core Structure: E-I Lamination, SiFe, Interleaved
      • Dimensions: 3-1/8″H x 3-3/4″W x 2-7/8″D
      • Hole Spacing: 3-1/8″ x 2-7/8″, center to center
      • Coating: Air Dry Varnish, 130ºC
      • Unit weight: approximately 5 pounds.
      • Part Number: 10-0134

This Bobbin Wound Inductor was built to mount on a printed Circuit board using through hole technology.

Basic Design: Unit has one “Trifilar” wound coil. Trifilar winding produces three coils which have nearly identical characteristics.

      • Turns Ratio: N1:N2:N3=1:1:1
      • Inductance Rating: L1, L2, L3 = 58-71 uH @ 1kHz
      • Core Structure: Ferrite PQ Core
      • Coating: Air Dry Varnish, 130°C
      • Unit Weight: Approximately 41.6 grams
      • Part Number: 130-0033

Completed Custom Built Bobbin Wound Inductor designed for avionics test application.

      • Application: Timer Transformer
      • Turns Ratio: NP:NS= 1:2.14
      • Inductance: Lprimary (L1, L2, L3, L4) = 29-67 mH Lsecondary (L5, L6, L7, L8) = 136-308 mH
      • Core Structure: Ferrite Pot Core
      • Coating: Air Dry Varnish, 130°C
      • Unit Weight: Approximately 20 grams
      • Part Number: 70-0257