- Transformers
- Auto Transformers
**Auto Transformer** - Buck-Boost Transformers
**Buck-Boost Transformers** - Current Transformers
**Current Transformers** - Dental Transformers
**Dental Transformers** - High Efficiency Power Transformers
**High Efficiency Power Transformers** - High Voltage Transformers
**High Voltage Transformer** - Intermittent Duty Transformers
**Intermittent Duty** - Low Inrush Transformers
**Low Inrush Transformers** - Low Noise Audio Transformers
**Low Noise Audio Transformers** - Low Profile Transformer
**Low Profile Transformer** - Medical Isolation Transformers
**Medical Isolation Transformers** - Power Transformers
**Power Transformers** - 3 Phase Transformer
**3 Phase Transformer** - 3 Phase Auto Transformers
**3 Phase Auto Transformers**

- Auto Transformers
- Inductors
**Inductors** - AC/DC Power Supplies
**AC/DC Power Supplies:**

Robust Circuit - Power Distribution Units (PDUs)
**Power Distribution**

Units (PDUs) - ISOLATION STATION
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## Linear Power Supplies

#### Unregulated Linear Power Supplies

When building unregulated linear power supplies, different rectifier circuits can be used. The most common circuits are the following:

##### Dual Complementary Rectifier

When a positive and negative DC output of the same voltage is required, a dual complementary rectifier is the best choice. The secondary windings are bifilar-wound for precisely matched resistance, coupling, and capacitance.

##### Full-Wave Bridge

The full wave bridge rectifier is the most cost-effective because the entire transformer secondary is used each half-cycle and no center tap is required.

##### Full-Wave, Center-Tapped Circuits

A full-wave, center-tapped rectifier is commonly used in high-current, low-voltage applications because there is only one voltage drop in the circuit. However, since only one secondary winding is used at a time, the transformer’s power rating must be about 30% greater than for a full-wave bridge transformer.

##### Full-Wave Center-Tap with Choke Input

Choke input filters are commonly used in high current applications because they reduce ripple and allow better utilization of the transformer’s power capacity.

#### 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

The formula to determine the transformer’s AC voltage and current (simplified version):

Vdc = Output DC voltage

Vreg = Voltage drop in the regulator = 3 Volt

Vrec = Voltage drop in the diodes = 0.7 Volt

Vrip = Ripple voltage = 10% of Vdc

Vnom = Nominal input voltage = 117 Volt

Vlow = Low line input voltage = 98 Volt

0.9 = Rectifier efficiency

Calculations for the transformer’s AC voltage and current, when used in the various rectifier circuits:

Rectifier circuits | RMS voltages (V) | RMS current (A) |
---|---|---|

Dual complementary | 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-tapped | VAC = 1.03VDC + 3.47 | IAC = 1.3 X IDC |