# The Naked Scientists Forum

### Author Topic: Converting currents  (Read 2217 times)

#### harryneild

• Full Member
• Posts: 88
##### Converting currents
« on: 05/05/2006 16:36:53 »
I know how people convert AC current into DC current using a diode bridge and a capacitor to recify the wave, however what is the method of converting DC current into AC current?

"Knowledge has to be improved, challenged, and increased constantly, or it vanishes." Peter F. Drucker
« Last Edit: 05/04/2007 21:57:05 by harryneild »

#### another_someone

• Guest
##### Re: Converting currents
« Reply #1 on: 05/05/2006 17:26:00 »
quote:
Originally posted by harryneild

I know how people convert AC current into DC current using a diode bridge and a capacitor to recify the wave, however what is the method of converting DC current into AC current?

A crude way, and not one that is commonly used, is simply to use a DC motor to drive an AC generator.

The common way (and the one that is almost exclusively the one used, at least for low power applications) is to use an oscillator or chopper.

A chopper is probably the easiest, where you just use an electronic switch to chop a DC current (i.e. to repeatedly switch it on and off).  The resultant square wave can then be smoothed using capacitors, and those same capacitors can also remove the DC offset voltage, so that the resultant output is centred around 0 volts (otherwise, the resultant wave would be centred around a voltage that was half the original DC voltage).  There are various other ways you can also use choppers (e.g. rather than simply switching the current on and off, you can switch between having the current flow one way, and reversing the connection so that the current and voltage work the other way on the other half of the cycle – this will remove the DC offset current at source, rather than having to correct for it afterwards).  There are also more modern ways of using digital waveform synthesisers that carefully shape the waveform, and so reduce some of the demands (and power losses) placed on the downstream capators.

George

#### The Naked Scientists Forum

##### Re: Converting currents
« Reply #1 on: 05/05/2006 17:26:00 »