Talk:Diode bridge

message: I've done a substantial rewrite of Diode bridge; at least two remaining items on my agenda for it:
* Rectifier is a redirect to here, but it should be a disamb between the sense of Rectifier diode (as opposed to e.g. laser diodes and LEDs) and the sense of Rectifier circuit; the latter is what should be linked from here.
* The attractive diagrams are not ideal, and my text tries to compensate for that on one hand, and to anticipate the two kinds of changes that could be made to them:
** If they are edited without being completely redone, the letters "AC" should be removed (twice) in each diagram except the last.
** If they are redrafted, putting the diodes one to an arm of a diamond-shaped figure, the inputs at opposite sides, the positive output at the top, and the negative output at the bottom would be preferable.  (Should color be made so crucial to understanding?  How about making only what is colored now, in the diagrams that have color, leaving the others, where no current flows, dotted.  Not a convention i recall ever seeing in electronics, but effective w/o color.)  The text description of the flows would change for that, and the wording would be much clearer and less awkward.
I'd also like to see half-wave rectification described, tho maybe it is just as well in Rectifier circuit.  I'm not sure about voltage doubler and tripler circuits, as to inclusion at all, or whether they belong with the bridges. --Jerzy 05:37, 2004 Jan 18 (UTC)
:I would like to see an extension for a three phase AC rectifier (with 6 diodes) and a reference to usage in automobile alternators, and a reference to the inventor, mr. Graetz. MH 213.51.209.230 19:00, 24 May 2004 (UTC)
thread_title: Rewrite

message: I really thnk that three phase and  polyphase rectification should be in a separate article and not included under diode bridges. Anyone else agree?
Light current 06:40, 1 August 2005 (UTC)
thread_title:  Poly Phase Rectification 

message: The extension of the article from diode bridge to DC power supplies that use diode bridges is really incomplete. Maybe this topic should be moved to a power supply article? There are a number of important topics that an encyclopedic power supply article could discuss about this circuit configuration, such as the potential of inrush current to damage the diodes, and the harmonic distortion that such a supply can impose on the AC source (to the extent that many supplies now include "power factor correction" circuits), the need for "bleeder" circuilts, and other practical information, most of which is not about diode bridges.
AJim 05:07, 7 July 2007 (UTC)
thread_title:  not an article about power supplies 

message: they are more important than just rectifiers (as I mentioned earlier)
*switches
AJim 05:07, 7 July 2007 (UTC)
replies: text: Indeed, I've also seen it used in an application with DC input, but a non-guaranteed polarity. (The plug fits either way). In that case, the bridge simply ensures a consistent polarity is provided to the rest of the circuit. (This is actually very smart use of the bridge, as it can prevent somebody from frying the circuit by plugging it in backwards). 66.254.241.199 (talk) 23:24, 30 January 2008 (UTC)
replies: text: Mostly that is rectifying, similar to an AC source. It is commonly used for polarity sensitive telephone circuits. There is, however, another use that links here: Power over Ethernet. In the PoE case, not only is the polarity possibly wrong, especially if using a crossover cable.  But also, power can be supplies on either of two sets of input pairs, and devices are supposed to work in either case.  The result looks like the polyphase rectifier described, for the four phase case. Gah4 (talk) 05:54, 12 October 2019 (UTC)
thread_title:  other uses of diode bridges 

message: As mentioned above, this section probably belongs in an article about power supplies. Nevertheless, as I judged this section to be quite confusing to those unfamiliar, I've prepared a fairly extensive re-write to add clarity and content.
Consider-
:"pulsating magnitude" 
:Surely it should read "amplitude"; and "pulsating" seems an inaccurate description of what I believe is correctly called "AC ripple".
:"One explanation of 'smoothing' is that the capacitor provides a low impedance path to the AC component of the output, reducing the AC voltage across, and AC current through, the resistive load. In less technical terms, any drop in the output voltage and current of the bridge tends to be cancelled by loss of charge in the capacitor." 
:First of all, the first sentence isn't "One explanation", it's an incomplete explanation. And "In less technical terms" isn't less technical, it's the back half of the rest of the story - the discharge of the capacitor. What about charging the capacitor?
:"Also see rectifier output smoothing." 
:See it where? There's no link.
There's a lot more confusion, but I don't want to be too harsh on those who obviously put in a lot of effort to create a what is overall a fairly informative article.
I'll post the re-write below, for comments prior to the actual edit. (As you may have noticed if you've checked the "History", I mistakenly saved a major edit earlier - apologies all around.)
:== Output smoothing ==
:A bridge rectifier supplies an output voltage of fixed polarity but varying amplitude, and consequently varying current amplitude, with the resulting waveforms exhibiting alternating peaks and valleys. These peaks and valleys occur at twice the frequency of the AC input. (see diagram above). This regular variation in amplitude is usually referred to as "ripple", and can often be heard as a low level hum from the speakers of AC-powered electronics when no source audio is present, for example, during the gaps between tracks on an audio compact disc (CD). (A fault in such equipment, and more commonly in the interconnecting cables, may produce a very loud hum; however, the presence of a loud hum rarely indicates a serious malfunction or failure.) For electronic circuits and some other applications, the addition of a power supply filter is required to lessen the variations in amplitude of the DC voltage and current present at the bridge output - to "smooth" the output. A simple filter may consist of a single capacitor (see diagram below), and is thus called a capacitor filter.
 
:
 
:The function of the capacitor, known as a reservoir or "smoothing" capacitor, is to lessen the variation in voltage of the DC output of the bridge - to "smooth" the waveform. The capacitor provides a low impedance path for the varying output voltage of the bridge, reducing peak voltage across, and thus peak current through, the destination load - the device the bridge is meant to power. The bridge output also "charges" the capacitor as its voltage rises. As the voltage falls, the capacitor discharges, resulting in a higher voltage at the load than is present at the bridge output. Thus, the drop in the output voltage and current of the bridge is compensated for by the loss of charge in the capacitor. This charge flows out as additional current through the load. In this manner, the variations in bridge output voltage and current are reduced, and their waveforms smoothed.
 
:The simplified circuit shown has a well deserved reputation for being dangerous, because in some applications, the capacitor can retain a lethal charge after the AC power source is removed. If supplying a dangerously high voltage, a practical circuit should include a reliable way to safely discharge the capacitor. If the normal load can not be guaranteed to perform this function, perhaps because it can be disconnected, the circuit should include a bleeder resistor connected as close as practical across the capacitor. This resistor should consume a current large enough to discharge the capacitor in a reasonable time, but small enough to avoid unnecessary power waste.
 
:Because a bleeder sets a minimum current drain, the regulation of the circuit, defined as percentage voltage change from minimum to maximum load, is improved. However in many cases the improvement is of insignificant magnitude.
 
:The capacitor and the load resistance have a typical time constant: \tau=RC, where C and R are the capacitance and load resistance respectively. As long as the load resistance is large enough such that this time constant is much longer than the time of one ripple cycle, the above configuration will produce a smoothed DC voltage across the load.
 
:In some designs, a series resistor on the load side of the capacitor is added. The smoothing can then be improved by adding additional stages of capacitor and resistor pairs, often done only for sub-supplies to critical high-gain circuits that tend to be sensitive to supply voltage noise.
 
:The idealized waveforms shown above are seen for both voltage and current when the load on the bridge is purely resistive. When the load includes a smoothing capacitor, it is a partially ([[reactance|reactive]) load, and both the voltage and current waveforms are greatly changed. While the voltage is smoothed, as described above, current will flow through the bridge only when the input voltage is greater than the capacitor voltage. For example, if the load draws an average current of n Amps, and the diodes conduct for 10% of the time, the average diode current during conduction must be 10n Amps. This non-sinusoidal current leads to harmonic distortion and a poor power factor in the AC supply. 
 
:In a practical circuit, when a capacitor is directly connected to the output of a bridge, the bridge diodes must be sized to withstand the current surge that occurs when the power is turned on at the peak of the AC voltage while the capacitor is fully discharged. Sometimes a small series resistor is included before the capacitor to limit this current, though in most applications the power supply transformer's resistance is already sufficient.
 
:Output can also be smoothed using a choke and a second capacitor - an inductance-capacitance or LC filter. (In electrical and electronic circuits, "L" represents inductance.) A choke tends to smooth current more than the voltage. However, due to the relatively high cost and weight of an effective choke, compared to a resistor and a capacitor, this method is not employed in modern equipment.
 
:Some early console radios generated the speaker's magnetic field with the output of the radio's high voltage ("B +") power supply, which was then routed to the other circuits. (Permanent magnets were considered too weak for good performance.) The speaker's field coil thus performed two functions simultaneously: it acted as a choke, filtering the power supply, and it produced the magnetic field for the speaker.
It needs a little more work. I'm going to sit on it for a while - see if I draw any comments.
Cheers!
Rico402 (talk) 00:03, 24 June 2008 (UTC)
thread_title:  Editing "Output smoothing" 

message: Please, correct information about the discoverer of the bridge using the patent information: https://depatisnet.dpma.de/DepatisNet/depatisnet?window=1&space=menu&content=treffer&action=bibdat&docid=GB000189524398A
Leo Graetz did not invent the bridge.  — Preceding unsigned comment added by 212.191.0.26 (talk) 18:57, 6 June 2013 (UTC)
thread_title:  Discoverer of the bridge 

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thread_title:  External links modified 

message: Capacitor input power supply is only one form of AC->DC conversion; what about choke input, resistor input, and regulated power supplies? None of this really
has to do with function and operation of diode bridges. I've edited all the filtering considerations way down (belong in other article).  Either we add the
above described other forms of PS input, or ditch the capacitor discussion altogether.  Even discussion of rectification itself already has its own article,
and should be kept strictly to understanding diode bridge configuration and operation. Sbalfour (talk) 20:20, 12 October 2017 (UTC)
thread_title:  Capacitor smoothing? 

message: What 'bout changing "Circuit arrangement of four diodes" --> "Circuit arrangement of four diodes converting AC into DC". This appears contested. Consensus?  209.6.123.10 (talk) 18:09, 18 June 2023 (UTC)
replies: text: I'm fine with it. JayCubby (talk) 01:04, 20 June 2023 (UTC)
thread_title:  Editing short description