Suggestion for USB power supply regulator

It is more common that we can use a portable USB power supply for charging up mobile phones. I know that Arduino accepts USB power as its power supply. By reading the schematic, I found that there is no voltage regulator for USB power supply.

My question is, how can I make a regulator for input voltage 4-5V and output voltage is more or less 5.0V for arduino? Or can we buy directly from eBay or somewhere else?

It is useful as I have one USB phone charger.

Thanks.

Get one of these https://www.adafruit.com/products/501 and whatever cable you need - USB-A to USB-B, or USB-Mini-B, or USB-Micro-B

You can find similar for plugging into cars as well. http://www.amazon.com/s/ref=nb_sb_noss?url=search-alias%3Delectronics&field-keywords=usb%20car%20power%20supply

Oh, what I mean is that I have a battery which has USB output. I want to make the battery as a portable power supply for Arduino, I want to make sure that the voltage is stable for Arduino.

If it has a USB output, why wouldn't it be stable?

CrossRoads: If it has a USB output, why wouldn't it be stable?

cos it said that I has 5.3V output. Also, for those made in China, I am not sure about their quality. I just want to utilize them.

Well, the Atmel chips are good with voltages up to 5.5V. You could use a resistor and zener diode and ensure the output does not exceed whatever level you are interested in. http://www.electronics-tutorials.ws/diode/diode_7.html http://www.dipmicro.com/store/1N5231B

You can't really regulate ~5v to 5v, well you can but you'd need a clever buck/boost arrangement and all to solve a problem that I don't think exists.

5v3 is OK BTW, but a bit close to the wind and I would not trust something that produced that voltage when it's supposed to be 5v. They are probably expecting a small voltage drop under load or something which is very dodgy.

If you don't trust a particular device don't use it.


Rob

Thanks for all of your reply. It seems that it is not the most reliable solution.

most supplies are +/-5% which is 0.25V maybe they rounded 5.25V up to 5.3V. All of the voltage regulator chips you get are 5% unless you pay much much more for them. did they state 5.3V or did you measure it ?

cmkpl: It is more common that we can use a portable USB power supply for charging up mobile phones. I know that Arduino accepts USB power as its power supply. By reading the schematic, I found that there is no voltage regulator for USB power supply.

My question is, how can I make a regulator for input voltage 4-5V and output voltage is more or less 5.0V for arduino? Or can we buy directly from eBay or somewhere else?

It is useful as I have one USB phone charger.

Thanks.

What you ask is SEPIC or Buck–Boost dc converter, Google it.

Buck (Step-down) - The output voltage is lower than the input voltage Boost (Step-up) - The output voltage is higher than the input voltage SEPIC - The output voltage can be lower or higher than the input voltage or equal to input voltage Buck–Boost converter - The output voltage is of the same polarity of the input, and can be lower or higher than the input or equal to input.

or u could make up u own one, use 1 Buck + 1 Boost or 1 Boost + 1 Buck or isolated ?uk or -5V + ?uk converter ...

electronics is art.