Jow,
The definitions of AC and DC you quoted are correct.
Now, what happens when there is a complex current of AC superimposed on DC?
This complex signal has two elements, one element is DC, which is a current in one direction, while the second element is AC, which is a current alternating periodically its' direction.
Can you envision such a complex current?
Also, do you know what a capacitor do?
What a conundrum.. 😛
I'm not too worried as long as none of this lets the magic smoke out..
To the OP: Nothing like a scope, DC supply, signal generator, and a couple of caps and resistors to experiment with to deepen understanding. I think you're missing the forest for the trees. As Mulder would say: "it's out there." (the answer...) 😀
I think this is a nice analogy Joshua. Like a road with a DC traffic stream of 100 cars/minute north-south, and an alternating (AC) traffic stream of 10 cars per minute changing directions every minute. The AC is real, but looking at the road in total you only see cars going north-south 😉
jan didden
Please let's try not to confuse the OP who is a newbie to electricity and electronics.
It me use a half wave rectifier as means to show my confusion.
"A rectifier is an electrical device that converts alternating current (AC), which periodically reverses direction, to direct current (DC), which is in only one direction, a process known as rectification."
If a AC is a change in voltage over time then how can the output be DC? The the voltage after the rectifier is still changing over time. It is simple changing from 0 volts to a peak positive voltage back to zero. If this is AC then definition of a rectifier is incorrect.
"A rectifier is an electrical device that converts alternating current (AC), which periodically reverses direction, to direct current (DC), which is in only one direction, a process known as rectification."
If a AC is a change in voltage over time then how can the output be DC? The the voltage after the rectifier is still changing over time. It is simple changing from 0 volts to a peak positive voltage back to zero. If this is AC then definition of a rectifier is incorrect.
Because, let's repeat it again, and again, AC voltage is a periodical change of POLARITY. In simpler terms, the voltage goes positive then negative, then positive, then negative and so on. However, positive and negative are purely relative terms in electricity. Nothing prevents your reference point to sit at some potential which isn't 0V (like the 150V on top of a diode plate).
This isn't the case for the DC you have after the diode. It goes positive, then zero, then positive... it isn't the same thing at all.
This isn't the case for the DC you have after the diode. It goes positive, then zero, then positive... it isn't the same thing at all.
Heat an air. Some electrical energy transforms to heat directly in amp, some in the air and on surfaces through mechanical friction.
It me use a half wave rectifier as means to show my confusion.
"A rectifier is an electrical device that converts alternating current (AC), which periodically reverses direction, to direct current (DC), which is in only one direction, a process known as rectification."
If a AC is a change in voltage over time then how can the output be DC? The the voltage after the rectifier is still changing over time. It is simple changing from 0 volts to a peak positive voltage back to zero. If this is AC then definition of a rectifier is incorrect.
Actually, output is NOT DC. It is of bell-shaped waveform. You can get DC from it only and only if you integrate it.
DC is Direct Current, that means in is constant and does not change in time.
THAT is one of the biggest problems we all have (Make PURE DC out of an AC supply),a doide rectifies AC but (converts it in PULSATORY DC) and then it needs to be smoothed by capacitors and coils to make it pure! But it will never be pure ! You only can get PURE DC with a battery!It me use a half wave rectifier as means to show my confusion.
"A rectifier is an electrical device that converts alternating current (AC), which periodically reverses direction, to direct current (DC), which is in only one direction, a process known as rectification."
If a AC is a change in voltage over time then how can the output be DC? The the voltage after the rectifier is still changing over time. It is simple changing from 0 volts to a peak positive voltage back to zero. If this is AC then definition of a rectifier is incorrect.
EL156
Exactly!! Keep in mind that current flows from negative to positive (actual electron movement). What is the real affect of a source that constantly changes its polarity? During one period actual current would flow in one direction of a conductor. To make it easier visualize the current flow from left to right on a conductor held horizontally. when the source switches its polarity the current in the conductor would flow from right to left. Its has reversed direction. As stated earlier the is the definition of AC.
Absolutely agree. However, the sine wave produced is a by-product of the source generating the AC (the constant reversal of polarity).
The unsmoothed output from a rectifier is sometimes called dirty DC. It is actually neither DC or AC, but a combination of the two. It is DC, with a value equal to the average waveform value, plus AC which is equal to the original waveform minus the DC value. Note that AC does not have to be symmetrical about zero.
Be careful about distinguishing between direction and position. AC does change direction, sometimes increasing sometimes decreasing. It does not necessarily have to change position from positive to negative. Wavebourn jumping up and down is still AC, whether he is at sea level, up a mountain, or visiting the Dead Sea.
Be careful about distinguishing between direction and position. AC does change direction, sometimes increasing sometimes decreasing. It does not necessarily have to change position from positive to negative. Wavebourn jumping up and down is still AC, whether he is at sea level, up a mountain, or visiting the Dead Sea.
Jow,
This is the most accurate answer, so far, for the shape of the current after a rectifying diode.
If you wish to understand, better follow from here.
Do you get that after the diode you get a bell-shaped current (or voltage), not DC?
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