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Reverse polarity for power connection.

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maniac84

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Hi guys, is there any power connector design which we can connect reverse but stil works? I mean like if I put pin 1 as Vcc n pin 2 as ground, then if I put pin 1 as ground n pin 2 as Vcc, it can work also. Is it by using two diodes?
 

If you use a bridge rectifier (4 diodes) it will do what you want. However, you do lose voltage (2 diode voltage drops).

Keith
 

Do you have the circuit for full bridge rectifier?
 

I googled it already... But seems like it is use to convert ac voltage to dc voltage. Is it for dc to dc?
 

Effectively your DC input is considered to be AC i.e. the connections could be either way round. So, what you have found is what you need to use.

It is not often used that way. Normally people use a single diode to protect against reverse polarity but then it won't work when plugged in the wrong way (but it won't blow up).

Keith.
 

Can u recommend a part number for the four diode? I wan to use on 24V.
 

What current? For up to 1A I would just use 4 diodes - 1N4001. If you want to reduce the voltage drop you could use Schottky diodes but they are a lot more expensive.

Keith
 

I am not sure. But i am connecting 24v to lm317. Any recommendation?
 

Go for something at least 2A forward current. Say, Vishay 2W005G-E4/51 or equivalent.
 

Can i use 1N5400? It got 3A forward current.
How do we determine the voltage rating for the diode?
 

ahgan84 said:
Can i use 1N5400? It got 3A forward current.
How do we determine the voltage rating for the diode?
Click to expand...

Pretty enough! :)

Don't bother about voltage rating, any silicon rectifier diode will support (reverse) voltages of at least 50V.

With forward biasing, every silicon diode will give you something around 0.7V voltage drop.
 

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