Hi,

I have output of 10V with low current. I also have power source of 5V with 500mA current (USB).
How can I combine these things to get 10V with high current?
I thought about buffer opamp - but output will be limeted to rails voltage (5V).
I do not want to use additional step-up converters.

 

Can't be done. Even if you use a step-up converter, you'll get less than a couple hundred mA at 10V. Additionally, you can't draw more than 100mA from a USB port unless you negotiate with the host and are allowed a higher current.

 

...
I do not want to use additional step-up converters.

The best you can do is about 200mA @ 10V, and that is only by using a step up converter.

I never cease to be amazed at why folks want to steal power from a USB port when these things are almost free at thrift shops and garage sales.

 

How can I combine these things to get 10V? I do not want to use a step-up converter.

I think we're having a problem with the definition of, "step-up converter". What else could increase the voltage of a 5VDC source? Until DC transformers are invented, you are stuck with making some sort of a converter.

 

Thank for the prompt response.
200 mA limit I understand.
Can I boost 10V signal to say 50mA?
The only reason I do not want step-up converters is to avoid additional coils in my schematic.

 

Thank for the prompt response.
Can I boost 10V signal to say 50mA?

We don't know..
Where is the 10V "signal" coming from?
Whats its source?

 

We don't know..
Where is the 10V "signal" coming from?
Whats its source?

I use voltage doubler to get 10V from 5V usb - but it drops current. And I want my usb current back - at least portion of it.

 

This might work.

 

Thank #12.
I will consider this ic

 

I will consider this ic

It still requires an inductor.

 

It still requires an inductor.

If you don't like inductors, you are welcome to name a switched capacitor converter for this job...or any other method.

Perhaps a 555 used as an oscillator with a voltage doubler rectifier configuration?

 

Perhaps a 555 used as an oscillator with a voltage doubler rectifier configuration?

Is this what you mean: http://www.instructables.com/id/555-Voltage-Doubler/
It says - "This circuit is only practical for low current devises".
But "low" current is different for different applications.
What current can I get from this circuit?

 

The comments on that page show this:

"my multimeter showed 18v@ 0.20A on the 10A setting, while using the circuit to power my 80mm 3-wire pc case fan at the Vin pin of the 555ic chip. i had 14v @ 0.14A from Vout to the pc fan."