220Vac to 5vCC without transformer

[farhada]

diagram nokia charger

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!

May I aske you a question, how do you connect the "command from the IC"?

Because the TRIAC will not work if you do not send a pulse to "open-up"

One good example can be found on:

You can have a much better using one of the other suggestions, and use a high power zener diode to get what you are looking for.

One important issue is to make sure you have a surge protecting device (like a transzorb) somewhere in your design, if not, any surge on your power will fry your device which will be much more costly than the amount you are saving by not having a transformer.

BR,
/Farhad

 

[tanveerriaz]

nokia celphone adaptor charger schematic

5V 0,5А
h**p://un7ppx.narod.ru/device1/power41.htm

 

[nicleo]

homebrew charger for nokia mobile

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%

I saw inductor looks like the one shown in the figure in one of my labs few years ago. I also know there is resistor looks like the one in the figure. That's why I get confused 8O

I tried to trace the PCB and found out that DEV1 was connected as a "PI" configuration with another TWO capacitors before the switching circuit. So, I think the "PI" circuit is a filter and therefore the DEV1 is an inductor. I also tried to place ohmmeter probes across DEV1 and the 'resistance' was only 5.6 ohm, which does not match 'orange-orange-brown-silver' reading of a resistor. So, I think DEV1 is an inductor. What do you think?

 

[samcheetah]

mobile phone charger circuit without transformer

well, in that case it might be an inductor connected in a C-L-C PI configuration as a filter. but i have to say that its really an odd type of inductor. maybe its a resistor being used as an inductor because at high frequencies the inductive reactance of an inductor is very high even if the inductance is low (as in case of simple resistors and wires). but im not sure about that. switching power supply design is very complex and it depends on the designer to choose from a number of topologies and even in that he has a lot of choices to optimize the switcher according to the load.

it would be great if someone who has designed switchers in an industrial setting would help in this regard.

 

[Shu]

power supplly without transformer

Nic,
I agree with you. It is an inductor. Based on colour, size and your measurement. Glad if you could trace the circuit.

 

[jmantilla]

using capacitors to reduce 220vac

you should preserve electrical isolation between the high voltage source and your circuit using a transformer, it can be really small by using an offline switching regulator... take a look at the following AN from Intusoft

http://www.intusoft.com/onsemipdfs/and8019.rev2.pdf

 

[samcheetah]

insulated triac schematic diagram

the PCB of the charger looks like a single sided PCB. could someone confirm this??????????????

 

[picotube]

nokia charger+schematic

Yes. It's a single sided PCB.

 

[muko]

220vac voltage regulator schematic

Try Viper12AS it is an offline smps IC that gives 150 mA @5V

 

[nikhilele]

schematic charger 110vdc

one more method is

 

[bauer]

nokia charger scheme

What is to be done to make these kind of circuits to deliver excess of 100mA and safety.....

 

[nikhilele]

nokia cell phone charger, schematic

how much current you want

 

[bauer]

220 vac switch mode power supply design tutorial

100mA approx..

 

[the_risk_master]

220vac to 5v dc+schematic

Hi,

I think that would be dangerous, it isnt easy to step down a 220V AC without transformer, Why would you do that for? (it's risky)

 

[nikhilele]

charge without transformers

for greater than 100mA following has good products
www.rohm.com

 

[PaulHolland]

i want 3v dc from 220ac with out ttransformer

Hi, Look at the dutch Electuur magazine page 121 2005 issue Nr 501/502. It uses a FET that is swiched off at about 8 Volts. Works perfect and you do not need expensive X2 capacitors BUT is is still unsafe since it connected directly to mains.

Paul.

 

[btbass]

www.power.elecdesign.com

You can use a buck regulator, something like Fairchild FSD210. I use one to step 450 volts down to 12 volts at 120mA. But be aware that this is a non isolated supply and any interfacing to the circuit is done through magnetic or opto couplers and a safety barier.

 

[PaulHolland]

220v ac to 5v cc

Does anybody know if its needed to use X2 type capacitors ??.. What is the regulation ??..

 

[yousafzai]

transformer 220ac

Is the voltage output of nokia charger is stable......

 

[nikhilele]

nokia charer pcb

if it is a good quality charges you will get pretty good voltage just add a filter capacitor and zener and you are ready to use it. u may use other voltage regulators LDO especially