HOME COMPANY PRODUCTS TECHNICAL DATA CONTACT ENQUIRY Site Search MIRACLE is established in the year 1994, the company has steadily expanded. It has started with manufacturing of complete Range of Laminated Transformers as well as Toroidal Transformers. Today it has positioned itself as a leading manufacturer all types of Toroidal Transformers, Laminated Transformers, Ferrite core Transformers, Flat - UI Transformers, SMPS and other voltage controlled devices. Read more.. Experienced R & D     department Production Capability Large Product line Reliability Reputation OEM Capability Buyer's Specifications     Accepted Huge Inventory Read more.. Downdload pdf Regulation & Temperature Rise DUTY CYCLE A smaller transformer can be used when the load is intermittent and the duty cycle is much shorter than the thermal time constant of the transformer (which is several hours). The power rating of the transformer is calculated as: VOLTAGE REGULATION The output voltage from the toroidal transformer increases slightly at partial load. By using larger diameter wire or a larger core, the voltage drop can be reduced and the regulation improved. TEMPERATURE RISE MIRACLE transformers are designed for a temperature rise of 60 degrees Celsius above ambient temperature at full load. At lower output power, the temperature rise decreases significantly. If required, we can provide the toroidal transformer with a thermal protector, which automatically turns off the transformer at a set temperature. ^Top Insulation & Shielding INSULATION SYSTEMS MIRACLE Toroidal Transformers are constructed with reinforced insulation and withstand 4,000 V RMS for 1 minute. Minimum creepage distance is 8 mm. STATIC SHIELDING When the toroidal transformer is used in an extremely noisy environment, a static shield might be needed to reduce the capacitive coupling between the primary and secondary. The noise suppression decreases with larger core sizes. The static shield consists of copperfoil laminated between polyester tape. Since the shield adds layers to the winding window in the transformer, a larger core size might be required. LOW MAGNETIC STRAY FIELD MIRACLE toroidals have a very low magnetic strayfield, with the primary and secondary windings uniformly wound around the entire core. For extremely sensitive applications the radiated field can be reduced further by winding a magnetic shield around the circumferenceof the transformer. A - Without magnetic shield B - With magnetic shield ^Top Unregulated Linear Power Supplies Different rectifier circuits can be used when building unregulated linear power supplies. The most common circuits are shown below. 1. Dual Complementary Rectifier A dual complementary rectifier is the best choice, when a positive and negative DC output of the same voltage is required. The secondary windings are bifilar wound for precisely matched resistance, coupling and capacitance. 2. Full Wave Bridge The full wave bridge rectifier is the most cost effective, since the entire transformer secondary is used on each half cycle and no center tap is required. 3. Full Wave Center Tapped Circuits A full wave center tapped rectifier is commonly used in high current, low voltage applications, since there is only one voltage drop in the circuit. However, since only one secondary winding is used at a time, the power rating of the transformer has to be about 30% greater than for a full wave bridge transformer. 4. Full Wave Center Tap With Choke Input Choke input filters are commonly used in high current applications, since they reduce ripple and allow better utilization of the power capacity of the transformer. ^Top Regulated Linear Power Supplies Regulated linear power supplies are used to provide a constant output voltage for different loads and varying input voltage. HOW TO SPECIFY THE TRANSFORMER A simplified formula to determine the AC voltage and current of the transformer is as follows: Vdc = Output DC voltage Vreg = Voltage drop in the regulator = 3 Volt Vrec = Voltage drop in the diodes = 0.7 VoltVrip = Ripple voltage = 10% of Vdc Vnom = Nominal input voltage = 117 Volt Vlow = Low line input voltage = 98 Volt 0.9 = Rectifier efficiency The transformer AC voltage and current, when used in the various rectifier circuits, is calculated as shown below: Rectifier circuits RMS voltages (V) RMS curent (A) Dual complimentary VAC = 1.03VDC + 3.47 IAC = 1.8 X IDC Full wave bridge VAC = 1.03VDC + 4.13 IAC = 1.8 X IDC Full wave center taped VAC = 1.03VDC + 3.47 IAC = 1.3 X IDC ^Top All rights reserved © 2006 Miracle.com Home  |  Company  |  Products  |  Technical data   |   Contact |  Enquiry Design: PlanetDesign