Something like these:
http://www.digikey.com/product-sear...t=0&page=1&quantity=0&ptm=0&fid=0&pageSize=25
But, you are dealing with the laws of physics. So there are variations in height, length, and width, but the volume will all be about the same for any AC/DC supply with your specs.

500ma seems a bit high for just a microcontroller. Plus, if you stick with 12V, you are going to have to add a regulator to drop to 5V for the microcontroller.

Ken

 

As pointed out before if its capable of running on 5 volts use a guts from a mini USB power cube. It's as small and cheap as you're going to get.

 

Interesting. Anyone ever open up one on the micro AC USB cube chargers?

OK, Googled: http://www.righto.com/2012/05/apple-iphone-charger-teardown-quality.html
and
https://www.google.com/search?q=mic..._wgZ3QAhUJ0oMKHVPgA4AQsAQIMg&biw=1600&bih=740

Note a link in there to his blog on fake Apple chargers.

Ken

 

230VAC to12VDC/500mA in 1.5x1.5x1.5cm(approx.)...not going to happen.

Ken

What about 9V/200mA

 

I thinks it's time for you to explained what you are trying to do. Juggling voltages and currents isn't going to get us anywhere. What do you intend to power besides a 5V microcontroller?

It's often easier for us to help solve your problem, than help solve you solution!

Ken

 

If you want the job done, just use a 7805 linear voltage regulator. Terribly inefficient though. put the 9V 200mA through the linear regulator and you're good to go in powering the atmega238. 12V500ma through the linear regulator is fine. JUST MAKE SURE YOU WIRE THINGS CORRECTLY.

 

B0M,
Read the whole thread to see the issues the OP and the rest of us are dealing with. It's not about getting 5V from 9V or 12V.
Ken

 

I thinks it's time for you to explained what you are trying to do. Juggling voltages and currents isn't going to get us anywhere. What do you intend to power besides a 5V microcontroller?

It's often easier for us to help solve your problem, than help solve you solution!

Ken

 The circuit basically consists of an AC to DC converter, ATMEGA328P Microcontroller, 5V relay and necessary plugs and sockets.
 The AC to DC converter is connected to input ac supply through a plug. This part consists of a transformer, a bridge rectifier circuit, a filter circuit and a voltage regulator (In addition, a fuse is also provided at the transformer input for safety purposes). This circuit basically provides the dc voltage(5V) to power up the microcontroller.
 Here we are using an ATMEGA 328P Microcontroller IC. It has a supply voltage of 5V and a current of 500 mA. This Microcontroller processes the temperature sensor output and controls the relay switching.
 The temperature sensor we are using is LM35 sensor. Its output is a voltage signal proportional to the temperature variation. This analog output is connected to the analog input pin of the microcontroller.
 A knob (or a pair of increment and decrement switches) is/are provided to control the reference temperature. These are connected to the digital pins of the microcontroller.
 A two digit seven segment display is also provided to display the current reference temperature value (in degree Celsius) set by the user.
 The relay coil is connected to a relay driver circuit, whose input is connected to the microcontroller digital pin. The ac input neutral line is connected to the NO (Normally Open) pin of the relay.
 Finally, the input AC Phase line and the Common pin of Relay are connected to a socket (Female) to which the FAN plug (Male) is connected.
 In addition, an override switch is also provided to turn ON and OFF the controller i.e. when user does not want the controller to control the fan Switching.

 

So it's all based around or can be based around a 5 volt system with a up to 500 ma current draw.

Standard $5 micro USB adapter, blah blah blah to be ignored again anyways for undefined reasons, power pack will do that and then some.

 

B0M,
Read the whole thread to see the issues the OP and the rest of us are dealing with. It's not about getting 5V from 9V or 12V.
Ken

Oh whoops. Um, if the OP wants something small, why not just get the tiny 1A Apple USB wall supply and have a short USB male adapter and solder it to where your micro controller is? If you want to build something really small, you need a custom PCB, SMD components and a small transformer. I honestly don't get why you need to make your own 120-240VAC to 5VDC converter.

 

B0M,

Read tcmtech's posts 9, 22, and 29. That was the suggestion. And my implication in my 23.

Ken

 

Buy a USB mobile phone charger with a 1 A rating.

 

Iam planning to implement the whole circuit on a double layered pcb, so anyone have the circuit diagram of a typical usb mobile charger

 

I'm done here.

 

Iam planning to implement the whole circuit on a double layered pcb, so anyone have the circuit diagram of a typical usb mobile charger

Power Integrations make such IC

LNK
TOP
TNY

series.

While it is possible to use some of these with just a plain 1000uH RF inductor, normally these are used with a small ferrite transformer.

 

Buy a Mobile charger, trace the schematic and transfer the schematic and the components to your board.