Many standard AC-DC switch mode power supplies (most of Lambda’s products) specify a high voltage DC input range in addition to the more common AC input range of 90-264VAC. We receive many questions about how and where to connect the DC input to an AC-DC supply that is spec’d to operate off of DC as well as an AC inputs.Where and why is high voltage DC power used? It turns out that many power generation facilities provide a high voltage DC to power the plant’s equipment rather than the regular 115VAC or 208VAC power grid. This high voltage DC (typically 120 or 130-330VDC) can be easily used with batteries to provide a secure source of power rather than using expensive centralized or local UPS systems.Now back to the subject. The topology of many switch-mode power supplies actually lends itself to operation from either AC or DC input. Important Note: Always check your power supply’s Operations Manual or spec sheet to confirm that it is designed to operate from either an AC or DC input.

Referring to the simplified power supply schematic below:When powered by an AC sine wave, during the first half cycle the current flows from the Line terminal through the input filter and charges capacitor C1 through diodes D1 and D3. During the second (negative) cycle, current flows from the Neutral terminal and capacitor C1 is charged through diodes D2 and D4.When powered from a high voltage DC source, the polarity of the connection is not critical as far as the operation of the power supply is concerned. polar ac unitIf the positive connection is made to the Line terminal, C1 is charged through diodes D1 and D3. air conditioning window units room sizeIf the positive connection is made to the Neutral terminal, then C1 is charged through diodes D2 and D4.what to do when ac unit is frozen

An important note of caution to insert here is about the protective fusing of the power supply. Internally most power supplies have a fast acting AC rated fuse in series with the Line terminal. It is recommended that a DC rated fuse be installed external to the power supply. If one side of the high voltage DC buss is connected to ground, then the fuse is usually positioned in series with the “hot” side (the ungrounded side). It is recommended that you consult with your local safety engineer to be sure. There was an error in this gadget Isolated & Non-Isolated DC-DC Converters What does 1U, 2U or 3U mean? What is PFC and why do I need it? What type of LED driver or power supply do I need? Class 2 or Class II power supplies? Over Current Protection in Power Supplies & Converters Efficiency Calculations for Power Converters Linear vs. Switch-mode Power Supplies Operating Power Supplies in Series What does SELV mean for Power Supplies?

TDK Corporation - Americas | Home > AC-DC > Power Systems Vicor offers  a wide range of AC-DC Power Systems, with up to 24 outputs, featuring autoranging, universal input, power factor correction (PFC) or three-phase inputs. There are several chassis sizes and styles to choose from, and multiple configurations available within each. Fan-cooled, coldplate, and chassis mount, conduction and liquid-cooled products are included in the range of AC-DC power systems. The products feature user-configurable outputs, including custom output voltages configured through online selection and configuration tools.Input: 100-240 Vac, 50/60 Hz, 0.35A. Output: 9Vdc @ 0-1.2A (set at 1.0A). 4' output cord with 1.3mm coax power plug. 9VDC 300MA WALL TRANSFORMER 9 Vdc 300 ma. Terminates with a 1.3 mm co-ax plug. A Note on Wall Transformers: A.C. and D.C. Wall Transformers are not regulated unless otherwise stated. They provide a specifi...ABSOPULSE offers a broad range of rugged, high-performance AC-DC switching power supplies, rectifiers and battery chargers.

Any AC to DC input/output configuration requirements, with power ratings from a few watts to several kilowatts, can be accommodated. Our AC-DC power supplies use high frequency power conversion topology and optimized magnetics to ensure reliability, efficiency and compact size. In addition, large design headroom, the exclusive use of qualified-in components, compliance with application-specific safety and emissions standards, and enclosure in robust mechanical packaging contribute to the long-term reliability of our power supplies. Today, our field-proven power supplies solutions operate reliably in industrial, railway, power utilities, military, marine, telecom and other harsh environments. Universal AC-inputs, 115/230Vac inputs, 47 – 440Hz or custom; PFC (Power Factor Corrected) input for EN 61000-3-2 harmonics compliance; Single or three-phase inputs; DC Outputs: 12Vdc to 250Vdc or custom; Output power from a few Watts to 30kW; Single or multiple outputs;

N + 1 redundancy and parallel operation; EMI filtering to meet required standards; Conformal coating or encapsulation options; Wide operating temperature ranges; IEC 61373 shock and vibration standards; EN60950-1 and corresponding UL and CSA electrical safety standards; 250W, Industrial Quality, Encapsulated AC-DC Power Supply with Conduction Cooling Compact, 3-phase high input voltage AC-DC power supplies; 50W, 100W, Compact, waterproof IP66 power supplies target heavy-duty industrial applications (AC-DC or DC-DC) 300W Waterproof, dustproof, IP66 AC-DC (or DC-DC) power converters with wide input ranges Let's say I need to power a 9v device with an input power source that is either AC or DC and changes almost randomly. Is there any way for me to detect in a circuit when AC changes to DC or vice-versa and have the circuit switch itself? Ideally I'd like to be able to design two circuits that would maintain power to the device constantly regardless of the input type and voltage.

Is there some circuit wizardry I can do that would be a pseudo switch or is it not possible? I'm more a software guy but I'd like to know a bit more about hardware, hence the almost noobish question. The wizardry lies in using diodes in series to be able to put DC power supplies in parallel without damaging them from (even tiny) differences in voltage, just like on the following diagram. Then from there, you can replace the second power supply by a rectifier which converts AC (of appropriate voltage amplitude, use transformers upstream if not the case - or DC/DC converters downstream) to DC. Note that in this setup, D2 wouldn't be necessary as the rectifier already prevents current from going upstream. For the explanation, diodes are analog OR gates: whichever has the higher applied voltage puts the diode in conduction, and the other prevents current from going in the other power supply. Warning: for this to work, at least one of the power supplies needs to have a floating ground (be isolated from eachother) or have the exact same ground, otherwise they're going to force eachother to different potentials and result in shortcircuits.

Finally, you may want to place a voltage regulator after the two power supplies because of the rectifier (which would allow you to place the battery straightaway as PS1). However, why not use mains-DC adapters that lie around to take care of the AC/DC conversion, and just make sure your battery + regulator and that adapter are put in parallel with diodes? If you have AC then feed it through a diode to convert to DC. You can do the same with the DC. If you use full wave rectifiers both AC and "any-polarity" DC will work. The two can be combined into one circuit and whichever power source produces the larger voltage will supply power to your 9V device. Also consider that you may need to use a voltage regulator. If the two power sources are independent and galvanically isolated it's easy. If the two power sources are not galvanically isolated then you need to think a little harder about how this is achieved. I have no way of knowing of course.Browse other questions tagged dc ac ac-dc or ask your own question.