Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Negative Power supply

Status
Not open for further replies.

gaboor

Member level 1
Joined
Mar 23, 2006
Messages
37
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,286
Activity points
1,558
Hi,

This is laways confusing me, how can you design a negative power suplly?! i mean what is the difference between - 5V power supply and +5v power supply with revrse polarity?!

I am sorry if it is a stupid question!!
 

Siniša

Full Member level 6
Joined
Jul 14, 2002
Messages
388
Helped
87
Reputation
174
Reaction score
18
Trophy points
1,298
Location
Windsor ON Canada
Activity points
2,692
There is not much difference if that is only power supply used. If you have ±5V, try building it with only positive regulators and you will see difference. You can't just stack positive regulators on top of each other as regulator is only sourcing current and does not sink, so your 0 won't be 0 any more.
 

senthilnathan.rajesh

Junior Member level 3
Joined
Apr 12, 2006
Messages
31
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,286
Activity points
1,518
Actually a positive supply can be treated as a negative supply if the supply terminals are interchanged. i.e "+ Terminal" of the positve supply can be treated as "GND Terminal" of Negative Supply. And the "GND Terminal of the positive supply can be treated as "-ve terminal" of the Negative power supply.

This how you can convert a positive power supply in to a negative (direct method).

But in the case of Dual Power suplies the above explanation won't hold good.

Example of constructing a Dual Power Supply from 2 individual positive power supplies as below (Basic - its very simple and self explanatory)

Image format see the link below

https://images.elektroda.net/82_1168361510.JPG

I think you could have understood.
 

sivakumar_tumma

Full Member level 4
Joined
Jan 27, 2007
Messages
195
Helped
9
Reputation
18
Reaction score
2
Trophy points
1,298
Location
India
Activity points
2,311
both postive and negative power supplies are same. Genarally same current will flow in both the terminals of the supply. we can use one as refernce. when positive terminal is used as refernce it is nagative power supply or else it is positve power supply..........
 

wisepie

Member level 4
Joined
Aug 1, 2005
Messages
78
Helped
7
Reputation
14
Reaction score
0
Trophy points
1,286
Activity points
1,706
This is depends on what is the reference voltage.
 

ryusgnal

Advanced Member level 4
Joined
Oct 4, 2005
Messages
102
Helped
3
Reputation
6
Reaction score
1
Trophy points
1,298
Location
Malaysia
Activity points
1,992
+5V power supply is when you connect the +ve terminal to the VCC node and -ve terminal to ground. And -5V is when you connect +ve terminal to ground and -ve terminal to VCC. As shown in the picture


2_1171528946.JPG
 

kender

Advanced Member level 4
Joined
Jun 19, 2005
Messages
1,422
Helped
138
Reputation
276
Reaction score
39
Trophy points
1,328
Location
Stanford, SF Bay Peninsula, California, Earth, Sol
Activity points
9,968
gaboor said:
i mean what is the difference between - 5V power supply and +5v power supply with revrse polarity?!
There's no difference, if both supplies are floating with respecto to each-other. In other words, they are not referenced to the same ground. Or in other words (yet again) the impedance between the 2 grund of 2 power supplies is high.
 

babinton

Member level 4
Joined
Apr 8, 2006
Messages
79
Helped
7
Reputation
14
Reaction score
5
Trophy points
1,288
Location
Nigeria
Activity points
1,959
HI, why not simply use an Ic voltage regulator. What you need to do is just ad an L7900 IC to the ouput of your bridge rectifier circuit. The particular IC ypu will use will depends on your desired output negative voltage. For example, if you need a
-5dc supply, use L7905. You can check the manufaturer datasheet on how to build the regulator.
regards.
babs
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top