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# How to use a transformer? Answered

I need to convert 240V Ac mains supply to 12V DC/ 24 V dc
How to do?
one way is transforming 220 V ac to 12/24 V ac using transformer and then using diode bridge and capacitor to convert it to dc
but i dont know how to use a transformer, how to implement it in a circuit......?

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## 13 Replies

Go out an buy a 220VAC to 24VAC transformer. Use a bridge rectifier to convert the 24V to DC. Then use a 12V voltage regulator to get the 12V you need. Or you can buy 2 separate transformers. One that gives you 24V and another that gives you 12V. You may be able to find one that already have 12 and 24 on the same transformer.

chatsbk007 (author)2013-06-11

thanks a lot
Aft converting to 24 V ac, wat capacitor shd I use
I never did a AC to DC thing before

mpilchfamily (author)2013-06-11

All depends on what you need from the 24VDC. What are your expectations from this power supply you want to put together? Have you researched any power supply schematics to see what is commonly used on a 24V supply?

chatsbk007 (author)2013-06-12

well i would use a transformer for a step down from 240V ac to 48V ac, then convert it to dc to make a led lighting system
I m posting a pic of the schematic I would be using pls comment

chatsbk007 (author)2013-06-12

https://www.instructables.com/files/deriv/FRI/FZ58/HHS9UJ5T/FRIFZ58HHS9UJ5T.SQUARE.jpg

mpilchfamily (author)2013-06-12

Where are your current limiting resistors?

I think you should look up an LED calc and input the information about your LEDS and power source and see what it recommends for wiring the LEDs and what resistors you'll need.

chatsbk007 (author)2013-06-12

well I shd have mentioned Leds are 4V, 0.02A
so after calculating manually, ifigured
If I hv voltage supply of 48V I wdnt need a resistor

mpilchfamily (author)2013-06-12

A current limiting resistor is always required with LEDs. Otherwise LEDs will draw as much current as the power source can handle till either the LED burns out or the power source fails.

chatsbk007 (author)2013-06-12

Then I think wd add a 1K resistor in the starting of each led chain

mpilchfamily (author)2013-06-12

Why 1K? Your voltages are about right for 2 strings of 12 LEDs. All you need is a 1 Ohm resistor on each string.

chatsbk007 (author)2013-06-13

well certainly
I wd put 1 ohm resistor at start of each chain
But I hv a nw problm
I gotta go buy 2day a nw soldring iron
the old one doesnt heat up

framistan (author)2013-06-11

You need to have 3 skills as I see it. 1st skill is to understand the mathematics to design it. The 2nd skill is to have the skill to be able to draw it as a schematic drawing.
The 3rd skill is to be able to build it according to your schematic. Which of the 3 skills are you having trouble with??

chatsbk007 (author)2013-06-11

well i have never worked wid ac
whenever i workd on circuits, i have a rechargable 9V battery or else i use AA batteries
for the first tym i require to use AC current
I need to make a led lighting system
From prior knwledge, I knw abt diode bridge and capacitor is used to convert AC to DC
but I nevr workd wid it cz I nvr reqd it