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  • Mr Richard Thrussell - Managing Director
  • Mrs Christine Thrussell - Company Secretary


SIGA (Electronics) Ltd is a specialist manufacturer of toroidal wound components, bobbin wound laminated transformers and associated assemblies. In 2011, SIGA is celebrating its fiftieth birthday. Over the last five decades we have steadily expanded our operations and now employ over 50 staff members who are involved in the production of a growing range of high quality wound components. All of our design, manufacture and test facilities are ISO 9001 approved, while our reputation for first class products and exceptional standards of customer service means a number of significant international companies operating in the electronics and aerospace industries call upon us for wound components.

Our skilled production teams are able to manufacture most types of transformer, while rigorous quality controls throughout the production process - from initial conception to final inspection - ensure the reliability of our products. As well as producing a range of UL recognised transformers which conform to UL506 and UL1411 requirements, SIGA has the specialist knowledge and CAD/CAM facilities to design, manufacture and test to most international standards, including EN60742, EN60601 and EN60950. A multitude of companies operating in the aerospace, audio, medical and instrumentation industries have benefitted from the experience and expertise SIGA has to offer.

So when you need laminated transformers, toroidal transformers, E and C-cored transformers and a range of UL approved transformers, look no further than the market-leading experts, SIGA.

Standard Toroidal Transformers

When you choose a toroidal transformer from SIGA's standard range, you'll benefit from a competitively priced, high-quality product that is compact and lightweight. A wide range of secondary voltage ratings are available. They have a dual primary winding input for operation from 120v or 230/240v, 50-60Hz. Toroidal transformers come supplied with 200mm flexible flying leads for reliability and ease of termination. For correct operation, windings should be connected in series or parallel. All of our transformers come complete with a mounting kit comprising of a clamping disc, foam washer, nuts, and bolts. Standard toroidal transformers undergo comprehensive testing throughout the manufacturing process and conform to the relevant voltage-proof requirements.

Custom Toroids

SIGA toroidal power transformers can be customised to suit your individual requirements. They can be made with a power output range from 1VA to 10kVA when operated from a 50Hz supply, though transformers can be supplied for use on 60Hz and 400Hz supplies. A range of core sizes are available to suit your dimensional requirements. While standard covering consists of a clear polyester tape finish, we can supply toroidal transformers that are vacuum varnished for protection against moisture when used in humid conditions. A selection of sleeved leads or insulated flex leads are available as the winding termination, as are non-standard types of termination, fixing and finishes. If you would like more information on our custom toroids, please don't hesitate to give SIGA a call.

Laminated Transformers

We manufacture and supply a wide range of bobbin wounded laminated transformers with power output range of 1VA to 5kVA at a frequency of 50Hz. A variety of assembly styles are available depending on the size of the transformer. The difference in assembly style is mainly down to the mounting method, of which there are three kinds; horizontal Printed Circuit Board mounting assembly, clamping type assembly for small and medium size transformers, and universal end frame assembly, suitable for larger sizes of transformer. Terminations come in the form of flying leads, bobbin mounted terminals, terminal boards or terminal blocks. Bobbins can be single or double sectioned, with or without shrouds.

Ferrite Cores

We use state-of-the-art winding machines and automatic soldering equipment to produce ferrite cores. Ferrite cores can be used in a wide range of bobbin wound and toroidal inductors and transformers. To ensure optimum performance over a range of frequencies, we make available a selection of ferrite materials. We can supply high frequency transformers and chokes using materials in the form of RM cores, ring cores, pot cores and E cores, as well as cores in the EFD, ETD, EP ranges. For high specification inductor applications, powder permalloy or HF iron cores are used, while LF iron cores are usually used for RFI suppression chokes and SMPU chokes.

Potted Toroids

For extra protection in harsh environmental conditions, toroids can be potted in circular shells or potting boxes. The plastic enclosure also makes an attractive uniform package. For some sizes of toroids, metal shells are available, offering improved electromagnetic and electrostatic screening. Potted toroids may have a central clearance hole or one or more threaded inserts, while terminations options include flexible flying leads, screw type terminals, and terminals suitable for PCB mounting. For more information on our potted toroids, please follow the link to the SIGA website or contact us directly.

Special Assemblies

Over the last 50 years, SIGA have been producing special coil assemblies for our customers' individual applications. We have accumulated a great deal of experience and expertise bringing their innovative development ideas to the production stage. So when you need a unique, application-specific assembly, you can count on SIGA. We work closely with your development engineers to finalise the design of your non-standard wound assembly. Special assemblies produced in the past include; foil wound coils, coils with special terminations or mounting, multi-aperture current transformer assemblies, current transformers, encapsulated coils for PCB mounting, C Core power transformers, medical isolating transformer assemblies, variable voltage transformers, switching mode power supplies, and many more. Just give us a call to discuss your requirements and get the ball rolling!

Medical Isolating Transformers

We have designed and built a 750V Isolation Transformer model to comply with the requirements of medical equipment specification BS EN 60601-1. These feature IEC inlets fused in each line, medical filter on input, IEC 6 way outlets, thermal circuit breaker illumination, inrush current limiters, and fused outputs, all within a 130mm H x 260mm W x 345mm D metal case with carrying handles. For electrical specifications, please follow the link to the SIGA website.

Technical Data

A typical temperature rise of 60°C occurs when operated at full load in an ambient of 20°C. Temperature rise data can be found on the SIGA website. Temperature rise also depends on the fixing method and ventilation available. The regulation of a transformer is calculated as follows: [(Off load volts - full load volts)/Off load volts)] x 100%. This regulation varies with the size and VA rating. If further technical advice is required, please contact the SIGA sales department.

Market Applications

SIGA (Electronics) Ltd caters for a range of market applications including medical, test equipment, aerospace and satellite, railways, high performance vehicles, underwater vehicles (ROVs) and more. For further information and to view image galleries of our work, please visit our website. If you have any questions about what we can do for you or for detailed technical information please get in touch and we’ll be more than happy to give you our best advice. We have a simple objective – to provide an efficient service to our customers to ensure that components are to the specification and quality required and are supplied on time.

Production Facilities

At SIGA we are well equipped with all the components required to facilitate a seamless production process.  From our bespoke computer-based design package that allows us to develop a variety of transformers and our extensive test facilities right through to our assembly options for medical isolators, we offer our customers a comprehensive service.  We are also able to supply tanks and autoclaves that are suitable for applications such as varnish impregnation, dipping and enveloping as well as automatic resin dispensing machines and our dedication to ongoing investment guarantees we are equipped to produce toroidal and bobbin components using the latest techniques and technology.


Technical Capabilities

Here at SIGA we have a simple objective – to provide an efficient service to our customers to ensure that components are to the specification and quality required and are supplied on time. Our technical capabilities are highly regarded. For more information and examples please visit our website where you can view graphs, diagrams and technical data. We are proud to have a BSI kitemark which backs up the standard of our work. If you’d like to know more about our technical capabilities or anything else please just get in touch and we’ll be more than happy to offer you our best advice.


We have considerable experience in the design of inductors and transformers and we’ve been meeting our customers’ specific requirements for approximately 50 years. Additionally, for very specific applications we are able to utilise the power of our bespoke computer aided design programme, allowing for a much wider range of transformers to be designed. Combined with an extensive library of technical information and very highly skilled staff we can ensure the optimum designs are achieved. We have a simple objective – to provide an efficient service to our customers to ensure that components are to the specification and quality required and are supplied on time.



Registration Number: 00683581
VAT Number: GB197 0975 14
Registered at Companies House:16 February, 1961 (58 years and 5 months ago)
No of Employees: 21-50
Annual Turnover: 2-5m
Company Type:
  • Manufacturer

Opening Times

Monday 07:45 AM - 05:30 PM
Tuesday 07:45 AM - 05:30 PM
Wednesday 07:45 AM - 05:30 PM
Thursday 07:45 AM - 05:30 PM
Friday 07:45 AM - 05:30 PM
Saturday Closed
Sunday Closed

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