A power supply performs the job of providing power to a battery run device, while also adapting the power coming from the mains power point to the appropriate voltage. An AC/DC power supply is also referred to as an adaptor or a charger. As adaptors, a power supply will convert the high-voltage AC (alternating current) that comes from the mains, into the DC (Direct current) that is required to recharge the batteries. AC has an alternating current whereby the electric charge flows back and forth, constantly changing direction. This allows the voltage to be easily converted. AC adaptors can be sourced from any reputable distributor such as RS Components.
The 12VDC power supply is one of the most common power supplies particularly the linear regulated 12VDC adaptor. A dissipative regulating circuit is used to regulate the output. They are considered very stable with an extremely low ripple and do not require switching frequencies to produce EMI. The linear regulator can be input to a range of voltages and works by dropping any excess input voltage in the form of heat.
Switched Mode Power Supply
The Switching regulated 12VDC power supplies, or Switched Mode Power Supply (SMPS) is more complex and is able to deliver more power according to its size. This uses an intricate high frequency switching method that utilises pulse width modulation as well as extensive EMI filtering and shielding. This technique diminishes any mode noise that is created.
Unregulated and USB
An unregulated power supply is basic yet reliable, consisting of a transformer, low-pass filter and rectifier. A disadvantage of the unregulated power supplies is that they retain a lot of ripple voltage.
USB chargers have become popular as an AC adapter for mobile phones and tablets. They are labelled according to voltage and though can be attached to any device, will not charge or operate a device that does not match its output.
The irreplaceable AC/DC power supply
The AC/DC power supply allows your device to run off a different voltage power source, can be replaced easily, extending the life of the device and works as a battery charger.
Other advantages are:
- As an adaptor, 12V battery chargers as well as any other voltage generates less heat, so lower amounts of energy are required. Once the battery is fully charged, the device can run without requiring more power.
- Using an external power adapter removes any problems around meeting safety requirements. For travelling, the power supply covers standards for many jurisdictions and allows a personal computer to be carried at all times.
- With a rechargeable battery and power supply, the device can be lighter and requires less electrical components.
A good power supply will include a universal full range AC input, have interchangeable AC heads, and provide Level VI efficiency or higher. It will offer input, output, and short circuit protection. Many power supplies come complete with interchangeable mains plugs for use overseas which is useful for business travelers. Common uses for power supplies are consumer electronics such as laptops, battery chargers, phones and LED lighting, telecommunications, electronics and instrumentation.