Power supply topology question ...

Could some electronics guru please shed some light on the following. The standard topology for a linear regulated power supply is basically as follows: isolation step-down transformer | v rectifier(bridge or 2 - diode) | v capacitor ripple filter bank | v voltage regulator | v capacitor ripple filter bank | V Let us suppose that the transformer is a step-down 9 - 0 - 9 1 Amp output device.

Now suppose I want to get two 1 Amp outputs by having a 9 - 0 -9 2 Amp transformer and splitting its output equally with resistors as : isolation step-down transformer | | v v resistor resistor | | V V rectifier etc., rectifier etc., Is this a valid topology ? Or should there be two 9 - 0 - 9 1 Amp isolation transformers connected to the common Ac wall input, and then parallel topology as above, without the resistors. Any thoughts, suggestions would be appreciated. Thanks in advance.

Reply to
dakupoto
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a 9-0-9 2A transformer is probably sufficienctly oversized

use one transofrmer, one rectifier, and one input capacitor bank. double up the regulators and everything downstream.

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For a good time: install ntp 

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Reply to
Jasen Betts

Draw the circuit with the ground/return(s). That, coupled with a clear definition/specification of your objective should give you the answer.

Reply to
mike

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No.  

Neglecting the transformer's regulation, whether the transformer is 
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Reply to
John Fields

On Mon, 04 Nov 2013 05:55:27 -0600, John Fields wrote:

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Reply to
John Fields

The resistors are unnecessary.

If you don't need it to be isolated, just make a 2A supply and hook the loads up in parallel.

I think you fail to understand the distinction between the current _rating_ on a supply and the current drawn by a load at a particular voltage, but I'm not sure.

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Tim Wescott 
Control system and signal processing consulting 
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Reply to
Tim Wescott

Thanks for the LTSpice file, but I use Ngspice, which like HSpice, uses text file input.

Reply to
dakupoto

Thanks. I am aware of the power rating, versus the actual current drawn by the load. Thanks to each of you for your feedback.

Reply to
dakupoto

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Sorry to have disturbed your turpor.
Reply to
John Fields

[snip]

Suggestions:

(1) Lose google and the added white-space (2) Get LTspice, it's free (3) If you must use NGspice, export the netlist from LTspice into NGspice. ...Jim Thompson

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| James E.Thompson                                 |    mens     | 
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Reply to
Jim Thompson

Who are you and what have you done with John?

Reply to
Spehro Pefhany

Could you please explain your question a bit ? I personally do not know who John Fields is, so I have no clue why he states that he has disturbed my torpor. Ngspice is freely-downloadable, compiles and can be installed very easily on any platform, especially Linux. I find it very convenient to use it especially when importing the sub-micron MOS files BSIM3, BSIM4 etc., that I often use in my work - for example I recently used it to analyze a 32 64-bit shift register structure with 15 nanometer MOSFET gate length. I am sure it would have taken me a lot longer, and would have made lot more mistakes, if I had set it up with a GUI based version of SPICE. taken me

Reply to
dakupoto

I gotta ask... If you can do this, how come you need to ask such a simple power supply question? Something seems horribly disconnected here.

Reply to
mike

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A ray of sunshine on an otherwise bleak day.  Thanks! :-)
Reply to
John Fields

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Strange, since you replied to my posts related to alleviating your 
misconceptions and power supply problems.
Reply to
John Fields

May the rest of the day be better.

Best regards, Spehro Pefhany

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"it's the network..."                          "The Journey is the reward" 
speff@interlog.com             Info for manufacturers: http://www.trexon.com 
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Reply to
Spehro Pefhany

Here is the answer Sir. I was just bouncing off ideas. May I point out that the first power supply, the one with 9 - 0 - 9

2 A rated output transformer has already built and works fine. I was just thinking of alternatives.
Reply to
dakupoto

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Did you have to add the current-limiting resistors?
Reply to
John Fields

+3

?-)

Reply to
josephkk

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