What happens if you connect:
AC with DC serial, same voltage
AC with DC serial, diff voltage
AC with DC parallel, same voltage
AC with DC parallel, diff voltage
AC with AC serial, diff phase(frequency?),same voltage
AC with AC parallel,diff phase,diff voltage
AC with AC serial, diff phase(frequency?),same voltage
AC with AC parallel,diff phase,diff voltage
:confused:
Posted on 2003-09-04 13:46:07 by inFinie
inFinie,
For all your questions about series connections, the total voltage at any instant will be the sum of each instantaneous voltage at that instant. For parallel connections, you do not connect different voltages in parallel. The highest voltage will force current through the lower voltage in a backwards direction. Ratch
Posted on 2003-09-04 21:08:27 by Ratch
When connecting AC with DC will output be AC?
Posted on 2003-09-05 03:46:09 by inFinie
inFinie,
Applying the method I described earlier, suppose we have 3 volts DC and 1 volt 0 to peak AC. Combining the voltages, we will have the resultant voltage varying from a maximum of 4 volts to a minimum of 2 volts. In other words, the AC voltage will be offset by a positive 3 volts. Try graphing the two voltages and see how that works. Ratch
Posted on 2003-09-05 10:01:40 by Ratch
AC voltage can be represented by:

v(t) = Amplitude * cos( wt + Phase ) + Constant

For pure AC, Constant = 0 Volts
In all cases w = radial frequency (w = 2*pi*f), t = time
Phase is like voltage, it only applys with two sources being compared.
If only have one AC source, phase is of little importance, since its a constant.


So to put a DC voltage in series with an AC would only alter the CONSTANT.


To place AC voltages in parallel, you have more trig going on. Assuming each AC source is the same frequency, you may or may not have phase issues (Phase 1 and Phase 2). If you have different frequencies as well, then you got wt(1) and wt(2).

To top this off, if you are in parallel then the voltages are very complex to describe. If in series, they add.

Hope this helps a bit.. its by no mean a complete walk thru...
:NaN:
Posted on 2003-09-05 12:56:49 by NaN
How will the constant be changed in AC series DC
v(t)=? if AC parallel AC
Posted on 2003-09-05 13:54:35 by inFinie
inFinie,

How will the constant be changed in AC series DC

The constant as given in the formula submitted by NaN will be equal to the DC voltage. You really should try to graph the two voltages by the way I described earlier to get a feel for how this works. First graph the DC voltage, second graph the AC voltage, then graph the sum of the two voltages.

if AC parallel AC

As I said before, you don't parallel two nonidentical voltages for the reason given in a previous reply. Ratch
Posted on 2003-09-05 20:52:57 by Ratch
In theory maybe you can't but i bet i can. And what will i read from oscilloscope if i do so.
And there is a problem i don't know how to graph those.
Posted on 2003-09-06 05:13:42 by inFinie
inFinie,
Graph it manually using a hand calculator. Use a few selected points of the waveform and plot the values. Voltages in series are added to obtain the total. It's easy! Ratch
Posted on 2003-09-06 05:36:48 by Ratch
Are you looking for the theoretical or realistic analysis?

Theoretical you ignore the supply impedance (resistance + capacitor and inductor reactance) and assume that the supplies can provide infinent current. These assumtions make it imposible to calculate the voltages for supplies connected in parallel since there is no resistance to divide the voltage across.

In either case, the open circuit voltage for supplies in series is simply the sum (even for A.C., remembering the A.C is varying).

When you 'mix' two A.C. voltages (signals) together, you get a signal that is composed of the original two frequencies, and the sum and difference of those frequencies. When you filter for one of the resultant signals, that is called hetrodyning. When you do this repeatedly, it's called super hetrodyning. Super hetrodyning is (was) commonly used in radios to convert the recieved signal down to a frequency that can be handled by the detector.

If you wish to determine the voltage of two real supplies in parallel, you must use network analysis. There are three methods; Norton, Thevinen, and some other. I don't recall how to use these. I belive Norton looks at one supply at a time, Thevin ignores how an impedance is connected, and the other looks at conductance/current flow.

The following pict shows A.C. riding D.C. (top) and two A.C. signals mixed (bottom)
Posted on 2003-09-06 06:12:07 by eet_1024