Full wave bridge rectifier

studiot

Joined Nov 9, 2007
4,998
It should be observed that the output of a bridge rectifier is not alternating (AC) and therefore does not strictly have a frequency in the AC sense.

However, it is not steady DC either. It is in fact pulsing DC or unidirectional current with a pulse repetition time equal to the pulse length of .00833... seconds - which equates to a pulse repetition rate of 120 pulses per second.

The graph of the output is not a continuous function.
 
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GopherT

Joined Nov 23, 2012
8,009
It should be observed that the output of a bridge rectifier is not alternating (AC) and therefore does not strictly have a frequency in the AC sense.

However, it is not steady DC either. It is in fact pulsing DC or unidirectional current with a pulse repetition time equal to the pulse length of .00833... seconds - which equates to a pulse repetition rate of 120 pulses per second.

The graph of the output is not a continuous function.
You are getting into semantics and I am not sure I are with definitions. AC is any non-DC waveform (including your "pulsing DC", square wave, rectangular e wave, triangle, sweep, ...) and therefore, any "waveform". AC does not have to be a sine wave, it does not have to oscillate +/- ground (it can have a DC offset and commonly does. AC is any signal that is not steady DC. Steady DC is rare other than battery with only a resistive load and no outside interference.

These non-sine wave AC signals are the whole point of the so-called "true RMS" volt meters. The are capable of measuring the true RMS voltage of non-sine wave AC signals.
 
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wayneh

Joined Sep 9, 2010
17,498
I'm with you on that. The term is alternating current, not alternating voltage. The thing that alternates is the direction of the current, not the magnitude.

Unfortunately the term "AC" is also widely used to refer to the changing magnitude of a DC voltage, the ripple around the mean DC. The electronics world seems to have no good acronym for this, to distinguish it from true AC.

Personally, I've decided to reserve the term "AC" for truly alternating current and use less handy, but more precise, terms for rippling DC.

I would still agree however that the answer to the OP's question is 120Hz. It's more complicated than that because it's not a sinewave and therefore has multiple frequencies, but I doubt the OP cares about that. He appears to be long gone anyway.
 

MaxHeadRoom

Joined Jul 18, 2013
28,702
I'm with you on that. The term is alternating current, not alternating voltage. The thing that alternates is the direction of the current, not the magnitude.
.
+1 on that.

For me the key is the current (alternating) change of direction, rather than pulsating.
Max.
 
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