Power Supply Adapter

Here the low power 12V transformerless power supply circuit with full-wave rectification. A lot of circuits could be powered straightaway in the electric mains using the support of a series capacitor (C1). The problem with this method is the fact that typically only one half cycle of the mains wave-form can be used to deliver a DC voltage. An obvious option is to work with a bridge rectifier to accomplish full-wave rectification, which improves the amount of current that can be delivered and makes it possible for the filter capacitor to become smaller sized. The associated circuit in fact does this, but in a clever manner that makes use of fewer parts. Right here we take benefit of the reality that a Zener diode can also be a standard diode that conducts electric current in the forward direction. During one half wave, the current flows via D1 through the load and back via D4, whilst during the other half wave it flows via D3 and D2. Keep in mind that with this circuit (and with the...

Offline switching power supply which resulting 5VDC/10A output from 110/220V AC home power electric. See the parts list, there should be different MOSFET type for 110V anf 220V volatage input. Below the diagram : And here the parts list: The schematic shows a 50-W power supply with a 5-V 10-A output. It is a flyback converter operating inside the continuous mode. The circuit has functionality of a main side and secondary side controller will full-protection from fault conditions such as overcurrent. When the fault condition has been removed, the power supply will go into the soft-start cycle just before recommencing normal operation.

This PSU has been especially designed for current-hungry ham radio transceivers. It delivers safely around 20Amps at 13.8V. For lower currents, a separate current limiting output, capable of 15ma up to a total of 20A has been added. The power transformer should be capable to deliver at least 25A at 17.5 to 20V. The lower the voltage, the lower power dissipation. The rectified current will be “ironed” by the C1, whose capacity should not be less than 40.000uF, (a golden rule of around 2000uF/A), but we recommend 50.000uF. This capacity can be built up by several smaller capacitors in parallel. The base of this design is a simple 12V regulator (7812). The output voltage can be brought to desired value (here 13.8V) by two external resistors (R5 and R6) using this formula: U= 12(1+R5/R6) The low currents (here 15mA) will keep the 7812 in its regular function. As soon as the current rises over 15ma, the voltage drop on R4 will “open” the Q3, actually handling the high output current. Thi...

If you are not experienced in dealing with it, then leave this project alone. Although Mains equipment can itself consume a lot of current , the circuits we build to control it, usually only require a few milliamps. Yet the low voltage power supply is frequently the largest part of the construction and a sizeable portion of the cost . This circuit will supply up to about 20ma at 12 volts. It uses capacitive reactance instead of resistance; and it doesn't generate very much heat.The circuit draws about 30ma AC. Always use a fuse and/or a fusible resistor to be on the safe side. The values given are only a guide. There should be more than enough power available for timers, light operated switches, temperature controllers etc, provided that you use an optical isolator as your circuit's output device. (E.g. MOC 3010/3020) If a relay is unavoidable, use one with a mains voltage coil and switch the coil using the optical isolator. C1 should be of the 'suppressor type'; mad...

This is transformerless power supply schematic diagram . Please take a note that this circuit running ONLY for input voltage 110V AC. I use this power supply for applications that doesn't use too mucho power. It can provide power to circuit that uses less than 100mA without any problem. The disadvantage of this circuit is the danger of an electrical shock, so it cannot be used if the circuit is in contact with the user. The voltage supplied by this is determined by the zener diode. The version of the transformerless power supply that uses a bridge rectifier provides more current than the first one because it rectifies both phases of the AC voltage.