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bridge rectifier......

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pjshah72

New Member
Hi,
Can we apply Mains (AC supply) to bridge rectifier? (If yes, can anyone suggest specific bridge rectifier for mains AC?

What should I consider when selecting bridge rectifier?

Thank you,
 

ericgibbs

Well-Known Member
Most Helpful Member
Hi,
Can we apply Mains (AC supply) to bridge rectifier? (If yes, can anyone suggest specific bridge rectifier for mains AC?

What should I consider when selecting bridge rectifier?

Thank you,
hi,
Yes you can apply mains directly to a suitable bridge rectifier.

You should consider the local mains rating voltage and the required current.

I guess you know there will be no isolation from the mains supply on the output.

E.
http://uk.farnell.com/jsp/search/br...arametricAttributeId=&prevNValues=2031+204537
 

pjshah72

New Member
hi,
Yes you can apply mains directly to a suitable bridge rectifier.

You should consider the local mains rating voltage and the required current.

I guess you know there will be no isolation from the mains supply on the output.

E.
http://uk.farnell.com/jsp/search/br...arametricAttributeId=&prevNValues=2031+204537

Thank you ericgibbs!!!!!!
I would like to try something today the lab, what could be the result when I apply Mains (AC) to the bridge rectifier and then DC to the same bridge rectifier. (I know for the DC, I will get some less voltage at output than input voltage because of the voltage drop of diodes.) But still wanted to try it out.

For isolation, I can use transformer after bridge rectifier when I applied AC mains. Is it correct?
My load (which is the what I am looking for as an output) 24Vdc with 2Amp current.

Thank you again for your suggestion.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
Thank you ericgibbs!!!!!!
I would like to try something today the lab, what could be the result when I apply Mains (AC) to the bridge rectifier and then DC to the same bridge rectifier. (I know for the DC, I will get some less voltage at output than input voltage because of the voltage drop of diodes.) But still wanted to try it out.

For isolation, I can use transformer after bridge rectifier when I applied AC mains. Is it correct?
No, the transformers goes BEFORE the bridge, DC doesn't go through a transformer.

My load (which is the what I am looking for as an output) 24Vdc with 2Amp current.
In which case you don't need a mains voltage rectifier, just a lower voltage (and higher current) one.
 

pjshah72

New Member
No, the transformers goes BEFORE the bridge, DC doesn't go through a transformer.



In which case you don't need a mains voltage rectifier, just a lower voltage (and higher current) one.
Hi Nigel,
I am looking to apply AC or DC to Bridge Rectifier first. Yes, DC can not go through the transformer and that is why my original post is about bridge rectifier (which is capable of both AC and DC.). I did not get your second point.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
Hi Nigel,
I am looking to apply AC or DC to Bridge Rectifier first. Yes, DC can not go through the transformer and that is why my original post is about bridge rectifier (which is capable of both AC and DC.). I did not get your second point.
You're wanting 24V DC, so you have a mains transformer that converts the incoming mains down 24V (or less), so the rectifier only works at 24V, not mains.

Perhaps you better explain EXACTLY what you're trying to do, because you don't seem to understand what you're mentioning here.
 

pjshah72

New Member
You're wanting 24V DC, so you have a mains transformer that converts the incoming mains down 24V (or less), so the rectifier only works at 24V, not mains.

Perhaps you better explain EXACTLY what you're trying to do, because you don't seem to understand what you're mentioning here.
Here is what I would like to do just as a test. (This is not for a specific application.)
Let's assume you are applying AC (Mains) to the rectifier, so you will get DC but high voltage DC. Now unplug the AC.
On the other hand, when you apply DC (30V) to the same bridge rectifier, you should get some less voltage then 30V as an output of bridge rectifier.

I know this is wired practice but wanted to just check it out.

To select bridge rectifier, I should know load and current and I am just taking 24V and 2Amp as an example so that I can choose bridge rectifier.
For further steps, I can put transformer to isolate source and load. (This is only when I applied AC power.) When I apply DC, there will be no transformer in the circuit.

I hope it clarifies my idea.
Thank you!!!!!!
 

Nigel Goodwin

Super Moderator
Most Helpful Member
As you're performing a VERY basic and obvious test, I would VERY STRONGLY advise you not to use mains voltage to do it.

While mains isn't particularly dangerous (particularly at USA voltages), there is still some degree of risk involved, and if you're performed such basic tests as this you're most probably not competent enough to do it safely.
 

unclejed613

Well-Known Member
Most Helpful Member
probably what would be better to do is to attach a DC-DC converter after the bridge rectifier. if you connect to an AC source, the bridge rectifies it and feeds the converter with DC. if it is plugged into a DC source, the bridge rectifier supplies DC to the converter (regardless of input polarity, the polarity into the DC-DC converter will always be correct). a "universal" DC-DC converter (one which works from 90V to 240V) would allow operation in any country, and also regardless of whether AC or DC (anywhere between 90-240V) is the power source. many modern wall wart switching supplies work like this. it's cheaper and simpler to make one model of wall wart that can be used everywhere, than it is to have two or more models of wall wart and have multiple BOM (bills of material) for equipment in a global market.
 
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