Science Buddies: "Ask an Expert"

I am in a FIX!! I am an 8th Grader from India... I am having this Science Fare on the 15th of October... I was doing the fare on A cordless Bell.... Only Yesterday my tutor told me No PLUGPOINTS WILL BE AVAILABLE... My project Stepdowns AC 220V AC into 18V AC but I dont hace a Plug Point sooooooo Plzzzzzzzzzzzzzz give me some idea on how to convert AC into DC!!!!!

Hi Roshan!

Supplying "how to convert ac to dc" to answers.com yields a wide variety of websites. Most of these appear to be commercial sites selling packaged AC to DC converters. These may not may not fit either your timeframe or budget.

One site: http://www.aaroncake.net/circuits/6-12conv.htm gives a circuit for a AC to DC convertor you can build yourself! That may fit your need.

Anyhow, I haven't been through all the answers.com output, which I encourage you to do. In addition, please see my posting "Search Sites" in this forum.

Hi roshanrules.

A diode, like a Zener diode, is normally used to convert AC to DC
for the volatge you are using, 18 V AC to 18V DC.

This web site has some good information about this:
http://en.wikipedia.org/wiki/Zener_diode

http://en.wikipedia.org

Do a Search on something like:
diode
rectifier

Do you have access to electronic components like diodes?

Hope this helps.


Good Luck!

Hi,

What is need to convert AC to DC is a " Diode Bridge Rectifier ". Here is a good link that explains the operation of this circuit:

http://hyperphysics.phy-astr.gsu.edu/hb ... ectbr.html

Another:

http://www.answers.com/topic/diode-bridge

The "zener diode", if needed, is used to set a reference voltage to control and regulate the output voltage of a power supply.

You may wish to read up on the meaning of " 18 volt AC " so that you will understand that when you wish to covert it to 18 volt DC, you will know where some of the voltage went:

http://www.bcae1.com/voltages.htm

The DC voltage out of a bridge rectifier will be slightly lower than the AC voltage that went into it, as their is always a "voltage drop" across the diode junction:

http://www.kpsec.freeuk.com/components/diode.htm

This last link is also useful for understanding the diode bridge operation.

Good Luck and happy experimenting.

Converting 220VAC to 18VAC is easy. Converting 18VAC to 18VDC is also easy. The way your request for help reads, it looks as if you do not have the 220VAC to start with. Is that correct?

If you need 18VDC, the quickest and easiest way is a battery. Three of the 6VDC batteries, intended to be used for large flashlights, wired in series should do the trick.
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