need help for voltage adder

[apurvmj]

Hi,
I join this forum for this problem,
I want a circuit which will add voltage of two DC sources, but mind you that they should not be in series. Their out put will be used as power source. Ex 9v+3v=12v @ 50w.
Thanks in advance.

 

[MikeMl]

Welcome to the forum. You will not always get the answer you want to hear...

Adding the voltage output of two supplies, is by definition, wiring them in series. (Kirchoff's voltage law).

To get 50W per your example, the load current would be 50W/12V = 4.17A. That means that the 3V supply would deliver 12.5W, and the 9V supply would deliver 37.5W.

 

[apurvmj]

Thanks for reply, you got it exactly what I wanted to say.(other forum couldn't understand my requirement). I came across summing op-amp, but I don't think it will work for those ampere ratings. I wish some circuit genius to help me in having some thing like op-amp like transistor configuration.
Thanks.

 

[MikeMl]

...I came across summing op-amp, but I don't think it will work for those ampere ratings. ...

The output load current from the output pin of an opamp comes from the power supply powering the opamp; not from the signals being summed...

 

[apurvmj]

#MikeMI
Thanks, I want any transistors configuration or any other circuit for above stated requirement.
Regards.

 

[kubeek]

Why can´t the supplies be in series? Being secretive doesn´t help much.
Anyway you could make a charge pump to sum the voltage even when the supplies are not in series. But probably not at 4A current.

 

[apurvmj]

let me put it in this way. we have two ac generators having diff. frequency & voltage, I want to utilizes their out put, them as if they are in series, I can use bridge rectifier & a capacitor as filter for both, but how can I connect them in series?
Hope I clarified myself this time.
Regards.

 

[kubeek]

Well if the generators are floating - i.e. they have no common connection between them, apart from the one you make, then you can simply connect the output of the two bridge rectifiers in series.
Better to measure the voltage between them or try putting a bulb in series before you connect the two together, just to be sure.