Is it possible to have both alternating current and direct current in same circuit?

Let's take a great example. I worked on a audio circuit (preamplifier) that ONLY had +12V DC power input, but provided a boosted AC audio signal output, based on an AC source signal input, with no special power supply used. How is this possible?

(Note: I'm assuming you might be thinking about signals, not just AC/DC power circuits).

If we have a DC-biased circuit, we have in this case op-amps that are "biased" (operating level set to) a DC voltage, say 6V. Our AC signal will be 'riding on top of' the DC voltage level, and go up and down accordingly.

The DC is removed at the output by using capacitors, which only pass AC signals. Therefore, it is possible! And very neat how it works.

:)

Yes it is possible to have both AC and DC sources in the same circuit.

In general, Vcir = Vdc + Vac. In a circuit with only an AC source, the voltage min and max will be equal to -Vpk and +Vpk respectively with a midpoint at 0V since Vdc = 0.

In a circuit where both AC and DC sources are present,

min = -Vpk + Vdc

max = +Vpk + Vdc

Having both DC and AC sources can be achieved by connecting an AC and DC source to the same point in the circuit.

It's possible. If you have an outlet for direct current and an outlet for alternating current. And that would bean that you have 2 lines of electricity coming in; Direct and Alternating. Where does that situation exist? Direct is based on Country. And alternating is based on Country. If you have Alternating in lets say, Japan, then you can't have direct in Japan. That's why, when you leave the US to go to another country, you have to make sure of their electric service. You might need to bring an adaptor for your electrical equipment such as hair drier, elec. shaver, etc.

What about clocks with battery backups.Or radios that run off of DC then have a battery option.I think the better question is can they be used at the same time? Not sure.

alternating means it crosses zero

so combining AC and DC will result in an offset therefore the output may or may not cross zero

some measuring instruments may measure either separately

some instruments will give a random answer

Di