Power Supply Unit "Energy Ultra-Prime"
- Board size - 100×100 mm
- AC outputs - Up to 3 AC outputs, including one center-tapped winding
- DC outputs - Up to 3 DC outputs, rectified, regulated
- Compatibility - DAC Rev 1.x and Rev 2.x
⚠️ Warning! This PSU operates with high voltage (220–240 VAC). Working with high voltage can be dangerous and may result in serious injury or damage if handled improperly. This design is intended for users who are familiar with electrical safety and DIY electronics. Always ensure proper insulation, grounding, and safe assembly practices.
Linear Regulated Power Supply "Energy Ultra-Prime" for DAC Projects - Overview
The "Energy Ultra-Prime" is a transformer-based linear regulated power supply unit with dimensions of 100 × 100 mm, designed specifically for DAC revision 2.x projects presented on this website (see "DAC Revisions and Power Design" in the about section for details).
The design uses two independent PCB-mounted analog transformers to provide dedicated isolated supply rails for the DAC sections. It provides AC outputs, as well as regulated, rectified DC outputs. Additionally, it offers the option to implement a "Virtual Capacitor" (Nazar's electronic capacitor) circuit for enhanced noise rejection. Three LM317 and one LM337 linear regulators are required to provide the regulated outputs. The PCB supports both DPAK (TO-252) and SOT-223 package footprints.
Input Stage and EMI Filtering
The input stage includes a basic C-L-C EMI filter. This helps reduce high-frequency noise from the incoming AC line and prevents interference from propagating into the rest of the system. It provides a practical level of filtering suitable for DIY audio applications.
Two separate fuses (F1 and F2) are used, one for each transformer.
Dedicated pads for RC snubbers are provided on the PCB bottom side to suppress transformer ringing. The footprint supports a through-hole (THT) capacitor. For the resistor, you can use either a 2512 SMD component or a through-hole resistor (a 0.5–1W metal oxide resistor is recommended).
Recommended snubber values:
- Capacitor: 4.7 nF to 6.8 nF (strictly X2 or Y1 safety-rated types for 250VAC).
- Resistor: 43 to 51 Ohm.
Transformer Configuration
The board is designed to support two PCB-mount transformers, each in the low-power range (typically around 5-7 W), allowing flexible configuration depending on the project requirements.
Transformer outputs can be configured based on the application:
- Transformer T1 (A) - symmetrical (bipolar) AC or DC supply (e.g., 17–0–17 VDC) for analog stages (I/V and LPF)
- Transformer T2 (B) - dual secondary AC or DC outputs (e.g., 2 × 7–9 VDC) for digital and analog circuitry
Rectification and Power Distribution
The "Energy Ultra-Prime" provides both raw AC outputs and rectified, regulated DC outputs.
Transformer outputs can be routed directly to the output connectors, allowing an AC supply to be delivered directly to legacy DAC revision 1.x boards if needed.
Alternatively, the same outputs can be routed through the onboard rectification and regulation stages. Three diode bridge rectifiers are used, followed by electrolytic capacitors for smoothing. The PCB layouts also include patterns to replace standard diode bridges with Schottky diodes.
Usage Notes
- This PSU provides both AC and regulated DC outputs; ensure correct connections depending on the target DAC board requirements.
- While the standard linear outputs (LM317/LM337) are fully sufficient for DAC Rev 2.x, you can optionally populate the "Virtual Capacitor" scheme. Make sure you are familiar with the pros and cons of this approach in audio circuits.
- Verify transformer wiring, pinouts, and output voltages before powering the system for the first time.
- Ensure proper insulation and safe handling of mains voltage at all times.
Design & Safety Compliance
To ensure a high level of electrical safety and prevent any potential tracking or arcing issues, the high-voltage section of the PCB has been designed in strict accordance with the IPC-2221A standard and IEC 62368-1 insulation requirements:
- Creepage and Clearance: Creepage distances between the live AC lines (Phase/Neutral) and the low-voltage DC planes are kept at a safe margin (over 6.0 mm) to deliver reinforced isolation. The high-voltage section utilizes 1mm milled isolation slots (air gaps) around the transformer mountings and phase lines to guarantee maximum dielectric strength and eliminate surface creepage currents.
- No AC Copper Pours: High-voltage AC tracks do not use copper pours, keeping capacitance coupling and noise leakage to a minimum.
- Safety Components: The input filtering stage is strictly designed for safety-rated X2/Y1 components.
- Gerberpsu_rev_3_8_gerber.zip