- 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
Auto Transformer
- Inductors
Inductors
- AC/DC Power Supplies
AC/DC Power Supplies:
Robust Circuit
- Power Distribution Units (PDUs)
Power Distribution
Units (PDUs)
- ISOLATION STATION™
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 |
