HV DC from mains AC?

Question

I would like to know if it is possible to convert the mains power 110/240V AC to 110/240V DC equivalent, that is output the same voltage in it's DC equivalent? What sort of bridge rectifier/smoothing capacitor should I use? I can probably use 1N4007, but what about the capacitor, electrolyc, ceramic, tantalum, plastic? And what farad value?

Answer 1

If you use direct 240 volt after rectification with filter you will get >350v dc after rectification (240x1.44 ) filter electrolytic capacitors Its VOLTAGE MUST BE >600 - 1000V PIV capacity  DEPENDS UPON THE LOAD CURRENT.What is the purpose of converting mains Ac to DC ? Which  equipment you are going to energise Is it a simple solenoid coil? or Machine ? .What is the load current ?.IN4007 ONLY CAPABLE OF maximum 1 amps , it will not drive exact 1 amps, it will fail.You have to use suitable(VA) transformer to reduce the input voltage (Better use Isolation transformer with multiple tape so that you can get required out put voltage or use variac) Go for Higher rating Diodes or Bridge rectifier 5Amps or 10 amps (or more )800V- 1000PIV rating It will be fail safe for any type of Inductive load.I have cover up little you need more information PM me

Answer 2

Dig out that old computer that is gathering dust in your closet. Remove the power supply. Inside you will find what you just described. The power from the mains come in and (after passing through a choke yes before it is rectified) it is rectified and filtered. This high voltage DC is then chopped at a high frequency to power a transformer that produces the low voltages required. Do not look for the circuit diagram on the internet because very few exist. Take apart that old power supply and see for yourself.

Answer 3

Connect 4 diodes 1n4007 in bridge,no filter capacitor,using direct AC 110 volts input. Output shall be 110 volts DC, but current limits to under 1 ampere. It is good enough to power a small DC motor or other device that do not need 99% pure DC source.

If you want the DC output less ripple ( hum sound ), you need to add a electrolyc capacitor in 1000 uF. 250 volts or better. This way,with no load,output can reach as high as 150 volts DC. At 500ma load,voltage shall drop into 120 volts DC. Never load more than 1 ampere.

If you need exactly 110 volts DC output all the time from no load to full load 1 ampere,you need to add a 110 volt regulator.

Answer 4

To get the equivalent power, the DC level out needs to be the same as the RMS value of the AC line, 110 or 240 volts.

Are you planning to use a transformer between the AC line and the rectifier? If so, what type -- center-tapped or non center-tapped?

Non center-tapped transformer:

A full-wave bridge rectifier will output twice the peak value of its input AC voltage at no load. For a 110 volt line, the peak voltage is 1.414 times the RMS value or about 155 volts. Doubling that value will result in a 310 volt output from an unloaded full-wave bridge.

Center-tapped transformer:

A full-wave (two diode) rectifier will output one-half the peak value at no load. Again, for a 110 volt line, the peak voltage is about 155 volts. With half of the AC on each side of the center tap, the output of the full wave rectifier will be about 77 volts.

In either case, you can either 1) adjust the AC voltage into the rectifier by picking the right transformer or 2) include some sort of regulator to reduce the rectifier's output.

The capacitance required will depend on the load on the supply and the amount of ripple that your circuit can tolerate.

Answer 5

A simple power supply uses a rectifier filter configuration.  A simple capacitor filter will give an unloaded output of 1.4 times the RMS AC voltage.  As output current increases the average voltage will decrease and the ripple will increase.  Choke input power supplies have a lower ratio and less ripple but require a minimum current.  If no current is pulled, the voltage goes back up to 1.4 times the input.  There are several things you need to specify in order to determine the required components including the output current (maximum and minimum),  allowable ripple, and the allowable voltage range (as a percentage of the input if desired).