220Vac to 5vCC without transformer

[jayxflash]

nokia charger schematic

I have this schematic diagram, I made it practically and is not working. I do not understand why, the circuit suposed to work with the sch, requests about 30mA, but the schematics offer only 3V. 7 days past and I don't know what to do... please give me some tips, or links to another schemes that work with no transformer to obtain 5vdc.

thanks!

 

[glenjoy]

nokia charger schematics

Hi,

How much current do you want to have? If only a small value, you can create a simple BUCK regulator, it is a switching power supply.

You can search google about tutorials on switching supplies.

 

[samcheetah]

nokia charger schematic diagram

by excluding a transformer from a power supply you are excluding a big advantage that transformers offer.........electrical isolation from the mains.

by not using a transformer you are putting your circuit at higher voltage levels which might be dangerous. but if thats not an issue then you can use any non-transformer method. by the way why do you want to stay away from using a transformer. is it because of their size?? well if thats the main problem then as already suggested you could use a switching power supply topology to reduce the size of the transformer.

i hope that helps

 

[jayxflash]

charger without transformer

I already said, I need 30mA. The circuit is for a sensor of movement. it's pretty expensive to build a switching source. that's why i need something simple like this. but still something functional...

 

[Ace-X]

5v without transformer

**broken link removed**

 

[nicleo]

switching regulator 220vac 5v

I already said, I need 30mA. The circuit is for a sensor of movement. it's pretty expensive to build a switching source. that's why i need something simple like this. but still something functional...

Switching power supply is not really expensive. Pls look at the latest charger of mobile phone, e.g. from Nokia. Mobile phone charger (or known as OFFLINE switching regulator) is usually able to deliver charging current of more than 500mA. At beginning I thought it was expensive. But we can buy it at a price not more than USD2.70 (remember, USD2.70 is RETAIL price, so the cost price will be more lower). More importantly, it provides isolation like AC-transformer based regulator. The circuit is simple and you can find dedicated IC to do the job for you. You can find this kind of circuits in On Semiconductor website.

 

[eltonjohn]

without transformer

Well it looks like a design with the price being the ultimate objective ..Probably you want a little of safety by the same money .
listen Is always possible to get 5 volts from 220v ac ..It depends on how much you want to spend .. The basic solution is rectify 220v and then use a voltage divider to get your 5 v . well not good !. too much drop ! too much waste of energy and very unsafe . You know the idea is to use a SCR and to turn it on for voltages lower than 5 volts ..The light dimmers are a perfect example on how to build this circuit .. You need a DIAC to turn your SCR ..for that ridiculous current (30 mA ) a triac is not even needed
but you need a cap to store some charge . just look for a light dimmer circuit . They work well but be carful and avoid power spikes during summer storms ,where i live even well protected power supplys fry ..!!

 

[samcheetah]

simple source without tranformer

Switching power supply is not really expensive. Pls look at the latest charger of mobile phone, e.g. from Nokia. Mobile phone charger (or known as OFFLINE switching regulator) is usually able to deliver charging current of more than 500mA. At beginning I thought it was expensive. But we can buy it at a price not more than USD2.70 (remember, USD2.70 is RETAIL price, so the cost price will be more lower). More importantly, it provides isolation like AC-transformer based regulator. The circuit is simple and you can find dedicated IC to do the job for you. You can find this kind of circuits in On Semiconductor website.

im really impressed by the size of the chargers that are avialable these days. can you give some specific links for those small switching mode chargers. and can you explain how does it provide isolation like transformer based supplies. i havent ever opened a Nokia charger but i do have a little idea about whats in there. do you know which ICs are used in most of those chargers

 

[nicleo]

mobile charger without transformer

im really impressed by the size of the chargers that are avialable these days. can you give some specific links for those small switching mode chargers. and can you explain how does it provide isolation like transformer based supplies. i havent ever opened a Nokia charger but i do have a little idea about whats in there. do you know which ICs are used in most of those chargers

Probably my sentence in previous post caused little misunderstanding. The charger still has one transformer, but it's very much smaller compared to conventional step-down 50Hz/60Hz power transformer. As a result, the size of the charger becomes smaller and lighter. The transformer (with ferrite-core) is not connected to 240VAC or 110VAC directly (that's why it's called OFFLINE, probably). I don't have the schematic. In fact, I'm also looking for one. I opened one charger (from Nokia) before. The charger was made in China. The circuitry was really simple. If I have a digital camera, I will capture a snapshot and let you see. But unfortunately, I don't have. However, I found one (almost) similar circuitry in On Semiconductor website ([url]https://www.onsemi.com/site/products/summary/0,4450,NCP1200A,00.html[/url], but the one in On Semiconductor was more complex.

 

[samcheetah]

nokia charger diagram

actually i have been wanting to open my nokia charger for a long time but the problem is that the screws have a pecuilar shape and none of my screwdrivers are able to open the screws. i believe that buying special screwdrivers for those screws is the only solution and for that i would have to do a little hunting around. anyway i would love to see a photo of the charger you have.

i do have a little knowledge of switchers and im very interested in making one. i have read that basically switchers directly rectify the mains voltage without stepping it down as in linear power supplies. then that rectified voltage is switched at a very high frequency. and then it is rectified down to the needs of the application. the high frequencies allows the use of small transformers and the switching methods help in increasing the efficiency of the switcher. but how is such a switcher isolated from the mains. is it because of that high frequency switchmode transformer? well if thats true then the high frequency oscillator and rectifier at the front end are not isolate from the mains. is that true????

 

[nicleo]

power supply switching 5v 220vac

i do have a little knowledge of switchers and im very interested in making one. i have read that basically switchers directly rectify the mains voltage without stepping it down as in linear power supplies. then that rectified voltage is switched at a very high frequency. and then it is rectified down to the needs of the application. the high frequencies allows the use of small transformers and the switching methods help in increasing the efficiency of the switcher. but how is such a switcher isolated from the mains. is it because of that high frequency switchmode transformer? well if thats true then the high frequency oscillator and rectifier at the front end are not isolate from the mains. is that true????

You are right that we need special tool to open the Nokia charger. As my mobile phone was lost and the charger is no longer useful, I used hammer to 'open' it. If I'm not mistaken, isolation from high voltage (240VAC/110VAC) is to protect our appliance (e.g. the Nokia mobile phone) from damaged. For the Nokia charger, before the high frequency transformer, there are few components, e.g. high voltage diodes, high voltage PWM controller, etc. These components are not protected, but it does not matter, as the main design objective is to protect the mobile phone from damage during charging. Besides, high voltage (few times higher than AC main voltage) diodes/rectifiers and PWM controller or switcher (you can find in On Semicondutor) are not expensive nowsaday. If those high rating components are used and if the spike at main power is not very high, then those components before the isolation transformer will still be safe.

 

[samcheetah]

nokia charger circuit diagram

I used hammer to 'open' it

i wish i could do that

until i get that special tool from somewhere, you work on getting a photo of that charger. and when you do that, just upload it here. i really want to see whats inside that charger.

 

[jayxflash]

switching ic 220 vac

I undertood that the schematic posted in the first topic, is something "classic". I'm not interested in safety at all, I just want to have 5v from 220v AC, in the CHEAPEST possible way. the circuit will function in a plastic case, so there's noo need for separation and etc.

 

[nicleo]

nokia schematic charger

I undertood that the schematic posted in the first topic, is something "classic". I'm not interested in safety at all, I just want to have 5v from 220v AC, in the CHEAPEST possible way. the circuit will function in a plastic case, so there's noo need for separation and etc.

Alright ... we're almost out of your topic.

Some References:

This one tells why the correct value of capacitance and the proper type of zener diode are important if you wish to have good regulation at higher current supply
**broken link removed**

Shed Some Pounds With This AC/DC Transformerless Power Supply
**broken link removed**

Transformerless Power Supplies: Resistive and Capacitive
[url]http://ww1.microchip.com/downloads/en/AppNotes/00954A.pdf[/url]

Transformerless Power Supply
[url]http://www.electronics-lab.com/projects/power/022/[/url]

 

[jayxflash]

see transformers relly mobile

and now the answer is quite simple. I have too large current (30mA). with the given schematics, it seems that supports only 15-20mA. I have to make some parts changes

 

[aNdreiBuuu]

rectification without transformer

the answer is quite simple: try to reduce the power consumption of your design under 5mA, or use an off-line switching regulator based on ViPER or Link familly from h**p://w*w.powerint.com/linktnproduct.htm

hope this help!
//a

 

[nicleo]

create dc from ac without transformer

until i get that special tool from somewhere, you work on getting a photo of that charger. and when you do that, just upload it here. i really want to see whats inside that charger.

Finally I borrowed a digital camera from my cousin and took few snapshots on the NOKIA mobile phone charger. Those snapshots are very high resolution, so you could zoom in and see the label of most of the ICs or components. For those labels that are blur or invisible, I have included 'text' besides them.

By the way, have you found the 'special' tool to open the charger? Do you think the tool is available in the market?

I have a question here. Pls refer to the inductor_or_resistor.jpg. Do you think DEV 1 is a resistor or an inductor? The device has 4 bands, i.e. orange-orange-brown-silver. Pls advise.

P/S: If you just wish to download and see for fun, probably you can download either one of the files (*_1.rar or *_2.rar) to save point. Both files are independent of each other. However, it's recommended to download both files if you wish to see the complete design of the charger. Enjoy!

 

[samcheetah]

220 v ac transformer

thanx nicleo those shots are great.

i havent been able to go to the local electronics market for a long time. my university schedule has kept me really busy these days. lots of tests in one row and add the assignments to the equation and u get a really messed up time schedule. anyway i will try to get time soon.

about DEV1, well it looks like a resistor to me. and if i remember the color bands correctly it is a 330 ohm resistor with a tolerance of 10%

thanx alot

 

[djalli]

circuit charger without transformer

I do not think a good power supply is without a transformer. It is cool to design but please consider consequences when to what you are applying it.

 

[Elavionic]

nokia charger circuit schematic

Take a look at Rohm homepage (The link is **broken link removed** ). They have some hybrid chip take can supply about 5V/100mA from 220V directely, non insulated. Smal size and a good price, about 5$. They are currently developing the same hybrids for 12V but insulated.