Power Requirements for the Web-888

The Web-888 device requires a USB-C power adapter for operation. These adapters are widely available and commonly bundled with modern smartphones. The Web-888 typically consumes more than 1A and can peak at around 1.5A. To ensure optimal performance, it is recommended to use a USB-C power adapter labeled as a "Fast Charger," as these are designed to deliver higher current levels.

Voltage Drops in USB Cables

The Web-888 requires a stable 5V input and may fail to boot if the voltage drops below approximately 4.75V. During moments of peak current usage, voltage loss due to poor-quality cables can cause power interruptions or system instability. To avoid this, use USB-C cables with sufficient wire gauge and low resistance to minimize voltage drop.

Improving Performance with a Low-Noise Linear Power Supply

A low-noise linear power supply can greatly reduce electromagnetic interference, particularly in the LF/MF frequency ranges. Most compact power supplies on the market today use switch-mode technology, which can introduce noise due to their switching frequencies (typically between 20 kHz and 170 kHz). Harmonics from these supplies may extend into shortwave bands, causing interference. While these power supplies generally meet regulatory emission standards, their noise levels can still degrade the performance of sensitive devices like Software Defined Radios (SDRs). For a detailed analysis of emissions and safety considerations for common 5V USB chargers, consult relevant resources.

Decline of Transformer-Based Linear Power Supplies

Transformer-based regulated linear power supplies have become less common, especially in compact, wall-mounted (plug-pack) designs. New energy efficiency regulations have contributed to this decline, as transformer-based supplies inherently consume more energy in standby mode compared to switch-mode alternatives. Additionally, SMPS units are more efficient overall. If you manage to source a linear power adapter, you may also need to build or acquire a DC-to-USB converter to make it compatible with the Web-888.

Considerations for Precision Bench Power Supplies

When using a precision bench power supply, set the current limit to at least 2A to accommodate the Web-888's peak current demands. Unlike standard linear power supplies, precision supplies are highly sensitive to over-current conditions and respond almost instantaneously. This can cause the supply to cut output voltage when the current limit is exceeded, potentially leading to issues such as unexpected shutdowns, failures during TF card operations, or server freezes under specific workloads.