Converting DC to AC: A Dangerous Endeavor?

[majeed11]

how to convert DC to AC??

how can i convert DC to AC from a battery(any voltage) for a transformer...?

 

[sepowens]

You need what is called an inverter. It takes the DC voltage and turns it into AC. It would be very helpful to know what you are wanting to do with this as there are a variety of parameters that can affect your choice of inverter depending on the voltage and purpose. Some cheap inverters for getting 120/220 mains AC from a battery or battery bank do not make pure sine waves and can destroy microwaves, computers, etc.

 

[majeed11]

for transformers i have to input it with AC only...but how can i convert it from a battery...i require low voltage AC(may 6-12V) for the transformer ...

 

[sepowens]

I will try to make the questions you ned to anwer clearer.
First, you need 6-12 volts FROM the transformer. What voltage, AC frequency and how many watts do you need going into it?

Now, the second part of myquestion again: What are you going to DO with this voltage? What frequency of AC is required for the transformer ANDthe circuit it is driving? How sensitive is the driven circuit to the waveform of the AC, e.g. audio circuits will click and hum, computer circuits may just die, clock circuits will not keep time, etc if the waveform is not a fairly close to a sine wave...

 

[edmondng]

just step down the 120vac to 6-12vac. is that possible or your main supply is battery (small device?)
otherwise just use a digital/analog converter to create your sine wave, go through an amplifier (with supply +-15v) to amplify amplitude

 

[hajirandi]

sir i want to convert (12v DC )to (12v AC) please tell me the name of converter or sujjetiojn that can i build it or not ... please guide me kashif

 

[isly ilwott]

Mechanically...take a 12vdc motor and drive a 12vac alternator.

Electrically...build an invertor.

To make it smooth...add 60Hz band pass filter.

 

[berkeman]

sir i want to convert (12v DC )to (12v AC) please tell me the name of converter or sujjetiojn that can i build it or not ... please guide me kashif

This is the kind of circuit that is being suggested to you, a "Power Inverter":

http://en.wikipedia.org/wiki/Power_inverter


.

 

[fest777]

hello iam trying to invert 120 dc to 120 ac, have a generator exciter that puts out 120 dc only, would like to invert to 120 ac to run small tools thanks anthony

 

[russ_watters]

First google hit for "120vdc inverter": http://www.novaelectric.com/dc_ac_inverters/nova_invert120cabinet.php

 

[fest777]

russ thanks for reply, the unit i saw is way too expensive , is there a simple circuit i can build to invert 120 dc to 120 ac thanks anthony

 

[berkeman]

russ thanks for reply, the unit i saw is way too expensive , is there a simple circuit i can build to invert 120 dc to 120 ac thanks anthony

What experience do you have working with voltages above 60V? And what experience do you have designing and building equipment to comply with Underwriters Laboratories (UL) standards?

 

[fest777]

very limited, iam very good a reading schematics and building things yet i don not have an electrical engineers degree. , any good ideas would help

 

[TVP45]

If you have a 6V or 12V battery and you only need a little current (< 1A), you could always pick up a solidstate radio vibrator. They run about $25 US.

 

[vk6kro]

Some portable power tools used on 230 volts use DC series wound motors on AC.
The field coil is in series with the rotor winding.

Not sure if this is the same with 110 volts, but if it is, then the 120 volts DC will work OK with such power tools.

You can easily check. With the tool unplugged, take out the screws and look at the wiring. If it goes through the switch, through the field coil, through another field coil then to one of the brushes on the rotor and from the other brush back to the power cable, then it is a series would motor.

If it has a speed control in the trigger this probably depends on it getting AC, so the tool would be unsuitable for running on DC.

 

[skeptic2]

russ thanks for reply, the unit i saw is way too expensive , is there a simple circuit i can build to invert 120 dc to 120 ac thanks anthony

The simplest, cheapest way I can think of is to use a DC relay that will operate at your supply voltage and wire one of its NC (normally closed) contacts in series with the coil and in series with the transformer primary. This will not give you a 60 Hz sine wave but you will have AC at the secondary of the transformer.

 

[zohaib javed]

hello can anyone tell me about why we use ac at particular performance and not use dc.where dc is required what is its reason of must use of dc,and similarly for ac?

 

[vk6kro]

At a power station, AC is generated by large rotating machines.
Similar machines could generate DC but this would be a lot more difficult as this would require moving contacts ("brushes") carrying thousands of amps.
AC generators do have moving contacts, but these carry a relatively small current.

AC is convenient, also, because there are advantages in efficiency in sending power around the country if it is done at high voltage.
This is easily achieved with transformers for AC but it is difficult to produce very high DC voltages for transmission lines and then to reduce them to a low voltage suitable for household electricity.

So, AC is produced and it is quite OK to use this for many devices that consume power.
Devices like electric heaters and some types of lighting work fine on AC, while others have to have the power turned into DC before it can be used.

Most electronic equipment works on DC, but it relatively simple to turn the AC power from the mains into smooth DC.

 

[Besoeker]

hello can anyone tell me about why we use ac at particular performance and not use dc.where dc is required what is its reason of must use of dc,and similarly for ac?

As has been mentioned, it is easy to transform AC up to higher voltages to get the economy of lower transmission losses and then easier to transform back down to lower voltages for domestic, commercial and industrial use.

That said, high voltage DC transmission is used for long or relatively long transmission lines. It requires conversion (AC to DC) and inversion (DC to AC). Modern developments in power semiconductor technology has made this easier to implement.

 

[disfoll]

I would like to convert 87 volt and 400 amp dc current into 120 volt and (220volt 50amp)AC how it can be made with every days item "scrap"?

 

[DaveC426913]

I would like to convert 87 volt and 400 amp dc current into 120 volt and (220volt 50amp)AC how it can be made with every days item "scrap"?

You are playing with very dangerous levels of electricity. Unless you have a lot of experience with electricity (in which case, you wouldn't be needing to ask) DO NOT DO.

 

[jim hardy]

I would like to convert 87 volt and 400 amp dc current into 120 volt and (220volt 50amp)AC how it can be made with every days item "scrap"?

that's 47 horsepower DC side, 15 on AC side! 25hp if it's three phase ..

not likely you'll find electronics that size laying around.

you need a DC motor perhaps 50 hp and similar sized generator.

 

[Redbelly98]

I would like to convert 87 volt and 400 amp dc current into 120 volt and (220volt 50amp)AC how it can be made with every days item "scrap"?

You are playing with very dangerous levels of electricity. Unless you have a lot of experience with electricity (in which case, you wouldn't be needing to ask) DO NOT DO.

What he said. Thread locked.