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Old 02-01-2017, 04:49 PM   #1
capwizard
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Default Full wave rectifier vs bridge rectifier?

This is a 25A 12v power supply use full wave rectifier on a bridge rectifier? is because the current? Why not use bridge rectifier connection?
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Last edited by capwizard; 02-01-2017 at 04:53 PM..
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Old 02-01-2017, 05:36 PM   #2
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Default Re: Full wave rectifier vs bridge rectifier?

http://www.electronics-tutorials.ws/diode/diode_6.html
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Old 02-01-2017, 06:01 PM   #3
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Default Re: Full wave rectifier vs bridge rectifier?

The Full Wave Bridge Rectifier, the main advantage of this bridge circuit is that it does not require a special centre tapped transformer, thereby reducing its size and cost.

I don't understand the manufacture wants cost-cutting they should take the advantage of The Full Wave Bridge Rectifier and uses smaller transformer?

PS: Some of the old 200A car battery changers their also use Full wave rectifier

Last edited by capwizard; 02-01-2017 at 06:12 PM..
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Old 02-01-2017, 09:28 PM   #4
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Default Re: Full wave rectifier vs bridge rectifier?

"Full wave rectifier vs bridge rectifier?" They are Both Full wave rectification. Full wave using xformer with center tap, one without center tap; both accomplish full wave rectification.
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Last edited by budm; 02-01-2017 at 09:29 PM..
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Old 02-02-2017, 09:29 AM   #5
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Default Re: Full wave rectifier vs bridge rectifier?

I need to open doors and windows, the smoke comes out from this bridge rectifier!

Isn't that bridge rectifier use half current compares to Full wave rectifier? (they connected this bridge rectifier as a Full wave rectifier!)

PS: Can I modify to bridge rectifier? The transformer is 12-0-12.
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File Type: jpg 20170202bfs_081445.jpg (520.1 KB, 9 views)

Last edited by capwizard; 02-02-2017 at 09:34 AM..
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Old 02-02-2017, 09:51 AM   #6
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Default Re: Full wave rectifier vs bridge rectifier?

Bridge rectifier IS FULL wave rectification, full wave using center tap transformer IS FULL WAVE. There are advantage and disadvantage for both of them but the end result output is still full wave for both type with ripple frequency twice of the AC input.
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Old 02-02-2017, 09:57 AM   #7
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Default Re: Full wave rectifier vs bridge rectifier?

Quote:
Originally Posted by capwizard View Post
I need to open doors and windows, the smoke comes out from this bridge rectifier!

Isn't that bridge rectifier use half current compares to Full wave rectifier? (they connected this bridge rectifier as a Full wave rectifier!)

PS: Can I modify to bridge rectifier? The transformer is 12-0-12.
What is that device? It looks like you have diode failure. What is the required output?
The whole pictures of the device? Your pictures are not showing all the wires of the transformer.
Are they using 12-0-12 to make dual output (+/-) suppliers?
It looks like they are using only half of the diodes in that bridge package, they are doing that form factor to make it easier to cool the diode package, it is full wave center tap rectification.

Last edited by budm; 02-02-2017 at 10:01 AM..
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Old 02-02-2017, 11:10 AM   #8
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Default Re: Full wave rectifier vs bridge rectifier?

This 13.8v 20A power supply. it makes Wuuh...Wuuh noise and smoke comes out, I found is the bridge rectifier did that.

I test the TRs (2N3055) none of them shorted, Caps needs to be change. I try to use Two bridge rectifiers to increase the current if that is the only problem.

PS: Can I use 40.0 AMPS. Schottky Barrier Rectifiers?
http://www.first-semi.com/DownFiles/...2011401166.PDF

I read:

Schottky diodes have a much lower voltage drop than the standard silicon types.

The Schottky diodes will work just as well as normal diodes, by arranging them as you normally would a bridge rectifier. They are not normally used in regulators because they are more expensive and sometimes physically larger. The advantages of a Schottky diode (low forward voltage, fast switching) will not provide any benefit for an ordinary bridge rectifier.
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Last edited by capwizard; 02-02-2017 at 11:30 AM..
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Old 02-02-2017, 12:00 PM   #9
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Default Re: Full wave rectifier vs bridge rectifier?

That last picture with the schematics makes me go "what the fsck...that doesn't make sense..."

I think using a 2-diode rectifier fullwave versus a bridge fullwave rectifier is a relic of the past for 60-cycle. Diodes used to be very expensive. No, not silicon diodes (well, maybe at first) - but definitely vacuum tube diodes. People were used to building full wave rectifiers with center tapped transformers and that carried on to silicon out there.

2-diode full wave still has a bit less power loss due to less drop, but costs much more to make the transformer - so nowadays bridges are the norm if halfwave isn't sufficient.

Now a bridge rectifier with center tapped transformer is a quick way to generate a bipolar supply which sometimes is still needed for op amps, etc. - if a charge pump is more expensive.
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Old 02-02-2017, 02:38 PM   #10
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Default Re: Full wave rectifier vs bridge rectifier?

In the pictures, it shows only three of the four terminal are being used, that is because it is using center tap transformer so they are using only two for diode inside that bridge rectifer, it is single not dual output supplies.
http://www.badcaps.net/forum/attachm...3&d=1486055357
Left drawing is wrong, look at how many terminals on the bridge rectifier being used in the unit. Your drawing has the bottom winding shorted out.
Right drawing you have FOUR diodes drops (2 Vdrops per each half of the cycle), wasted power.

See how it is wired yet?
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File Type: jpg Recitifier wiring.jpg (2.14 MB, 10 views)
File Type: jpg make no sense.jpg (1.31 MB, 17 views)

Last edited by budm; 02-02-2017 at 03:07 PM..
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Old 02-02-2017, 03:08 PM   #11
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Default Re: Full wave rectifier vs bridge rectifier?

budm..........You are the BEST! Thank you very much.
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Old 02-02-2017, 06:32 PM   #12
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Default Re: Full wave rectifier vs bridge rectifier?

put some star diodes in there ...
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Old 02-02-2017, 07:45 PM   #13
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Default Re: Full wave rectifier vs bridge rectifier?

so does it smoke if the bridge output is disconnected from the filter capacitors?
Any luck finding where the actual fault is?

hmm... nice to have a high current CV PSU... I only have an SCR-regulated 15A variable CV/CC. Its regulation is pretty horrible.

Last edited by eccerr0r; 02-02-2017 at 07:47 PM..
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Old 02-03-2017, 02:15 PM   #14
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Default Re: Full wave rectifier vs bridge rectifier?

Y...YYY...YES I fixed it!................"Any luck finding where the actual fault is?"......The problem is the bridge rectifier!.........

I like to experience with science projects, "The Schottky diodes will work just as well as normal diodes." So, I sub to two KCF16A60s, parts from used common Plasma TV regelation diodes, Ultra – Fast Recovery 16A 600v.

PS: I will use heater coil as 1 ohm resistor to test the current of this power supply.

PS: Dont bug me because this is mine.
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Last edited by capwizard; 02-03-2017 at 03:19 PM..
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Old 02-03-2017, 02:32 PM   #15
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Default Re: Full wave rectifier vs bridge rectifier?

Paralleling diode without balancing will have problem, the one with lower Vf will have most Vf the current flowing through it, and when it heat up the Vf goes down more so more current flow that and then you will have thermal run away.
I hope dual-diode package has really close Vf.
BTW, Ultra fast for this application is not going to be better, Vf is 1.7V at 8A per spec, so power dissipation will be 1.7V x 8A =13.6W/2 (DUE TO 50% DUTY CYCLE) = 6.8W at 8A Ambient of 25c, so at 20~25A you will see more power.
You want diode with lowest Vf as posiible.

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Old 02-03-2017, 02:38 PM   #16
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Default Re: Full wave rectifier vs bridge rectifier?

I will use heater coil (pic1) as a (13.8v / 20A =) 0.68 ohm resistor to test the current of this power supply. Any better and cheap idea to test the 20A current?

PS: Car headlights are pretty good!
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File Type: jpg Open Coil Heater - Dual Element.jpg (652.7 KB, 5 views)
File Type: jpg 20170203_135437.jpg (407.0 KB, 4 views)

Last edited by capwizard; 02-03-2017 at 02:59 PM..
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Old 02-03-2017, 02:48 PM   #17
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Default Re: Full wave rectifier vs bridge rectifier?

Quote:
Originally Posted by capwizard View Post
I will use heater coil (pic1) as 13.8v / 20A = 0.68 ohm resistor to test the current of this power supply. Any better and cheap idea to test the 20A current?
Is that Hot or COLD resistance? Material type?
https://farnam-custom.com/resources/...r-coil-design/
http://electronics.stackexchange.com...er-dissipation

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Old 02-03-2017, 03:05 PM   #18
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Default Re: Full wave rectifier vs bridge rectifier?

Use the cold resistance is better. (...........to do that you'd need to know the temperature of the heated wire... calculating that would be non-trivial, especially in airflow..........) just merge the coil inside A bucket of water, it is at low voltage should be OK! Does headlight more safe?

Last edited by capwizard; 02-03-2017 at 03:13 PM..
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Old 02-03-2017, 03:30 PM   #19
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Default Re: Full wave rectifier vs bridge rectifier?

Weird that the diodes died, usually PSUs the other components die. It looks like in this case this PSU the weak point is the rectifier :o

Honestly I have never tried my bench PSU at 15A, I sort of just assumed it will work. It does have an ammeter and I've driven DC-120VAC inverters with it as a test load. Using 22 gauge wire with the AC inverter to power a 100W incandescent lamp causes enough drop to make it stop working properly, not to mention the wires get warm/hot...
22 gauge isn't enough for 10A. I doubled up/tripled up as a workaround.
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Old 02-03-2017, 03:55 PM   #20
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Default Re: Full wave rectifier vs bridge rectifier?

To eccerr0r: my next project is the 40A 12v or 96v 5A (lots combinations) power supply. it needs eight 12V 5A AC Adapters, I still collect them. It is A Universal AC Adapter Modular Power Supply.

PS: Use four 12v 5A AC Adapters (up to 12v 20A) can replace the one I just fixed.
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File Type: jpg sku_152373_2.jpg (63.2 KB, 5 views)

Last edited by capwizard; 02-03-2017 at 04:13 PM..
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