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zaveri • Dec 8, 2012

# Running an A.C device on D.C power

Supposing an A.C machine has to be run on a D.C source, such as a battery, through an oscillator circuit, then what should be the voltage and current of the battery, provided we know the voltage, current, frequency of the A.C device as well as the efficiency of the oscillator.
Jeffrey Arulraj • Dec 8, 2012
Post the current and VOltage reading Then the required circuit is easy to predict But remember this the required battery voltage must be minimum Sqrt(2) times more than the operating voltage of the device

If 220 V then the battery supply must be of Sqrt(2) * 220 got it
zaveri • Dec 8, 2012
Sqrt(2) = 1.414

hence 1.414 * 220 = 311.08 volts.

is that so ?

by the way, what about the current?
Jeffrey Arulraj • Dec 8, 2012
True cos the DC voltage got from a rectifier is 1/sqrt(2) times the AC supply voltage. So for the converse to take place you need the product of Vdc and sqrt(2) to get the rated voltage

Let us hear if this is proper [Prototype] do comment here buddy
lal • Dec 8, 2012
Well, it would be better to use an Inverter I guess (Assuming the frequency is not in MHz range). An oscillator is actually not used to provide any power output. Usually the current in oscillator circuits are very low. But an inverter is designed to provide power.
[Prototype] • Dec 8, 2012
Conqueror
True cos the DC voltage got from a rectifier is 1/sqrt(2) times the AC supply voltage. So for the converse to take place you need the product of Vdc and sqrt(2) to get the rated voltage

Let us hear if this is proper [Prototype] do comment here buddy
Not very much sure about this conversion. If you consider the voltage to be RMS, there's a one on one relationship between AC & DC i.e. 10V AC = 10V DC.

But as lal said, you will not be able to derive much current using normal oscillator circuit. Its better to use an inverter, but building/buying one could be expensive.
Jeffrey Arulraj • Dec 8, 2012
[Prototype]
Not very much sure about this conversion. If you consider the voltage to be RMS, there's a one on one relationship between AC & DC i.e. 10V AC = 10V DC.

But as lal said, you will not be able to derive much current using oscillator circuit. Its better to use an inverter, but building/buying one could be expensive.
That leads to another question Supply we receive in our houses are rated 220 V AC what is it is RMS or 0 to peak
lal • Dec 8, 2012
That is the RMS value. 240V AC supply at 50Hz is our standard.

A bit of confusion though, I learnt it as 240V but now wiki says it is 220V. Some other sources say it is 240V itself. It is the RMS value whatever. Need to shed some light.
bioramani sir which is the right one?
[Prototype] • Dec 8, 2012
Conqueror
That leads to another question Supply we receive in our houses are rated 220 V AC what is it is RMS or 0 to peak
That 220V is RMS itself.

lal
That is the RMS value. 240V AC supply at 50Hz is our standard.

A bit of confusion though, I learnt it as 240V but now wiki says it is 220V. Some other sources say it is 240V itself. It is the RMS value whatever. Need to shed some light.
bioramani sir which is the right one?
Its normally stated as 220-240V because the power supply keep on fluctuating between those values, however, they ensure the minimum and maximum value are not violated.
solar morpher • Dec 8, 2012
zaveri use an inverter as others have said supply voltage of 220 V from mains is sufficient and current based on the life time you desire and the charging time you desire fix them That should do it
lal
That is the RMS value. 240V AC supply at 50Hz is our standard. A bit of confusion though, I learnt it as 240V but now wiki says it is 220V. Some other sources say it is 240V itself. It is the RMS value whatever. Need to shed some light.
bioramani sir which is the right one?
Inverters are basically power oscillators with wave shaping to get nearly pure sine wave. Good ones are expensive but better than normal grid supply. This is a basic article on inverters: https://electronics.howstuffworks.com/gadgets/automotive/dc-ac-power-inverter2.htm

India won't be India unless there is some confusion. So, we have two voltages. Single phase domestic supply is 230V and three phase is 240V/415V.
This table is quite useful and can be kept for reference:
https://www.sensorcentral.com/worldsupport/standards12.php
zaveri • Dec 10, 2012

honestly speaking i don't think i can afford an inverter.

obtaining the power from the battery though an oscillator and then stepping up the voltage using a step-up transformer ?
Jeffrey Arulraj • Dec 10, 2012
When a voltage is stepped up you will not adequate current in the op side

This is cos more energy than the ip cannot be derived at the op of any device

So if u step the voltage up the current drops in the op side causing the device not to work
zaveri
obtaining the power from the battery though an oscillator and then stepping up the voltage using a step-up transformer ?
That is what an inverter does.
See if any of these do it yourself ideas will work for you:
https://www.instructables.com/tag/type-id/?q=inverters&sort=none
prashanth463 • Dec 10, 2012
sorry for this basic question, do we have a device that can amplify voltage and current simultaneously?
prashanth463 • Dec 10, 2012
sorry for this basic question, do we have a device that can amplify voltage and current simultaneously?
Jeffrey Arulraj • Dec 10, 2012
yeah CE amplifiers do that but provide a phase shift But mostly this current amplification is not sufficient so we go for multi staging
prashanth463 • Dec 10, 2012
But ce amplifiers are good voltage amplifiers not current amplifiers right?
Please correct me if i'm wrong
prashanth463
sorry for this basic question, do we have a device that can amplify voltage and current simultaneously?
If that can be done, the first law of thermodynamics will be violated. Output Power is always equal to input power minus power consumed by the device.
prashanth463 • Dec 10, 2012
Oh so now i understand, either voltage or current can be amplified so that the law is satisfied
but sir i have another doubt, class A ce amplifier are good current amplifiers and as it is a ce amplifier it also amplifies voltage, so does this mean that this kind of amplifier voilate first rule of thermodynamics?
lal • Dec 10, 2012
In amplification, an extra source other than the input signal is made use of. Power is added to the input signal from this extra source to amplify it. Input power thus includes the input signal power and the source power.
zaveri • Dec 11, 2012
Conqueror
When a voltage is stepped up you will not adequate current in the op side

This is cos more energy than the ip cannot be derived at the op of any device

So if u step the voltage up the current drops in the op side causing the device not to work

so you mean to say that voltage is increased at the cost of current ?
ABCD ABCD • Dec 11, 2012
Well, if you are using a incandescent lamp or something similar, then you can also power it up with DC. But, you need to look for the safe DC voltage that can be used.
zaveri • Dec 11, 2012
mreccentric
Well, if you are using a incandescent lamp or something similar, then you can also power it up with DC. But, you need to look for the safe DC voltage that can be used.
i am going to use a small cabin fan. what about it ?
ABCD ABCD • Dec 11, 2012
zaveri
i am going to use a small cabin fan. what about it ?
Then you can't use DC as is it. It works only for incandescent bulbs.
There are any number of DC cabin fans that will run on 12 V or 24 V battery.
Here is one:
https://www.natashaindia.com/product_info.php?id=34
ABCD ABCD • Dec 11, 2012
bioramani
There are any number of DC cabin fans that will run on 12 V or 24 V battery.
Here is one:
https://www.natashaindia.com/product_info.php?id=34
Thats nice... zaveri, It'll be easy to use if you have an UPS(battery), or you can use a old car battery to run this(?).
Jeffrey Arulraj • Dec 11, 2012
zaveri
i am going to use a small cabin fan. what about it ?
In a transformer and other static devices true

But in the case of CE amplifiers the external DC serves as an input and that is utilised for increasing the op power of the signal
zaveri • Dec 12, 2012
mreccentric

Are you sure, that we can't run any A.C motors in this manner ?

Conqueror

what do you have to say to this ?
Jeffrey Arulraj • Dec 12, 2012
Small cabin Fan's rotor need alternating supply to provide the varying flux required to drive them. So they cannot be driven using a DC supply I am sure about it friend
lal • Dec 12, 2012
AC motors are called AC motors because they work on AC. These motors make use of a rotating magnetic field for their operation which can only be generated with the help of an alternating current.

There is a type of motor called universal motor which can work on both AC and DC. Those are series wound motors. You can probably see it in a mixer grinder.
ABCD ABCD • Dec 12, 2012
zaveri,
i'm sure about it. Else, is your DC source pulsating? But even that requires a circuitry. Better use a fan specifically made for DC. Acc to me, that's the simplest answer i can give.