5V Ac to DC Regulated Powersupply




About: When the world drives you crazy, go to instructables.com and learn something new instead

So I've been searching for ways to make my own power supply so i can stop using so many wall warts.  I use alot of DC, i'm tired of 5v 350ma small fries.  
I'm working on an ATX power supply but it lacks the compact portability I need in a simple power supply.

This cost about $5.50 with the step down transformer being the most expensive part.

Old power chord (free)
Step down transformer ($3.00)
Full Wave Bridge rectifier (50V 4A) ($1.50)
5V regulator (I used an L7805CV 1.5A max) ($1.00/3)
smoothing capacitor (I used 100 uF 35V (free))
wire (free)
And the essentials: soldering iron flux solder, electrical tape, heatshrink tube, pliers, lighter, ect.

Step 1: Setting Up the Transformer

Connect the AC input of the transformer to the power chord (put heatshrink tube on first reinforces the tape)
Wrap it in electrical tape
Shrink the heat shrink tube
Plug it in and make sure it has some sort of output, actual voltage out doesn't matter.

Step 2: Rectification Smoothing and Regulating

Connect the output of the transformer to the bridge rectifier, measure the output it wont measure a full 12V (the nature of the rectifier)
Also wrap the AC inputs in heat shrink.

Connect the regulator to your positive and base of the rectifier.
facing you left to right the regulator goes input, base, output

Attach the smoothing capacitor to the positive, and base. i'm not sure if this actually does anything in my circuit but the voltage comes out constant and it went under life test with no shorts or anything funky so i'm assuming it does work.

Secure, wrap and insulate everything.
Test it out.

Step 3: It Works!

It works at a 5v output, cool right? I think it is.

I'm not sure how this will work if it shorts out, it may fry the transformer.

Input voltage: the wall
rectifier: 4A max
Output voltage: 5v regulated 1.5A
max current: limited by the rectifier, and regulator, multiple rectifiers and regulators can be used just as long as the wattage doesn't max out your transformer

Some sort of heat sink is going to be instituted, probably some glue or silicone coating the rectifier and regulator.

Anything special I should know about this like if it's incredibly dangerous? or maybe that my capacitor isn't doing anything.
This is only being plugged into a power strip that powers the lighting I use that's why i don't have a switch on the AC
I thought about a fuse in hindsights

"Power Supplies." Welcome to the Electronics Club. Web. 16 Apr. 2012. <http://www.kpsec.freeuk.com/powersup.htm>.



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    10 Discussions


    6 years ago on Introduction

    i have a transformer of 14V secondary with 500mA current.Can i make the current 250mA somehow.The question is not exactly related to this but i wondered if could get some answer.

    1 reply

    Reply 6 years ago on Introduction

    From what I know of AC the current rated on your transformer should be the max it can supply. All the transformers I've used have just a wattage rating.
    It will probably have to be in your circuit that limits the current.
    Just a shot from everything I know of AC currents.


    Reply 6 years ago on Introduction

    That is used to filter out noise caused by other parts of the circuit.
    When your load increased suddenly you will increase a draw on the current from the supply, that causes the voltage to change too. The capacitor just acts as a little storage so the voltage doesn't drop during increased loads.