Power Supply - Step Down Transformer

Hi shaik.thameem, if i understood you well, you need a system that can step a voltage of 220/240 volt a.c to around 15 volt d.c without much losses?

I'd advise you specify the ratings of the load you would want to use it on, that would help in advising whether you should go for transformerless power supply or stick to step down transformer.

About the diode that can rectify 220vac giving 220vdc? yes a lot of diodes can do that but issue here is the expected load, hence it's determined by the quantity of current that would pass across it.please give a clearer picture of what you want. thank you!

thanks for replaying to my message, as you told to me to inform about the load, its around 1.5 to 2 amps.

Without transformer it would be dangerous to have power = 15*2 = 30 Watts. So it is best to use transformer. Life is safe.

have fun !

thanks for replying me, i am using LM 317 regulator for reducing voltage 20V D.C to 12V DC which is having 1.5 amps capacity, thats why i wanted 1.5 amps to 2 amps capacity diodes for converting AC to DC which will give 1.5 amps capacity. Or is there any kind of method or device where we can get this requirement without transformer? please help me thanking you sir

thanks for replying me, i am using LM 317 regulator for reducing voltage 20V D.C to 12V DC which is having 1.5 amps capacity, thats why i wanted 1.5 amps to 2 amps capacity diodes for converting AC to DC which will give 1.5 amps capacity. Or is there any kind of method or device where we can get this requirement without transformer? please help me thanking you sir

Solution 1: Go to local electronics market and ask for Zener Diode 12v-2A 24watt-30Watt.

Solution 2: Use capacitor in series with 220v, it is cheeper and fatal for circuits ahead of it, for detail put phares in google " voltage drop using capacitor ".

Also read these :

http://forums.makezine.com/comments.php?DiscussionID=2819

http://www.aaroncake.net/circuits/6-12conv.asp?showcomments=all

Have fun.

Your answer is perfect......and brings a touch of safety back to this blog.

GA.

There are 3 ways of reducing the voltage of your AC supply. The most dodgy way is to put a resistor or capacitor in series. This gives very poor regulation and may dissipate a lot of heat. The next way is to use a transformer. The efficiency is good and the safety is good too. The last way is to use a switched-mode power supply, as in all computer power supplies these days. However, I suspect that for your application a switched-mode power supply would not weigh a lot less than a transformer.
http://en.wikipedia.org/wiki/Switched-mode_power_supply

http://en.wikipedia.org/wiki/Switched-mode_power_supply

http://cpc.farnell.com/_/spu25a-106-15/psu-s-mode-15v-25w-cec/dp/PW02163

That's about $30.

Jusst use thyristors to "cut" alt 220 v when RMS is 15V of sin function. You can also buy ready to use chip that would do that.

Is your transformer big enough? Too small would bring problems. A small amount of "over" power with the transformer is also a good idea to keep temps low.......

There are many diagrams on the web using the components you have, just do a search.

Have you got the data and or applications sheet for the LM317(?), often there are good examples on how to use it......find it on the web......if you need a website, just ask us here....

Keep us up to date...

Switch mode power supply = simple and lightweight and small for that power requirement.

I agree entirely, I build them for my own usage (from a fantastic 10 amp 5-40 volt Elektor design!).

But for a beginner, I feel they are a little bit dangerous when building and he has the components it would appear already for a more conventional one.....