dual polarity power supply - Electronic Circuits Projects Diagrams Free

Wond3rboy · 20th July 2008, 12:38 PM

i have made a dual power supply i dont understand why i dont get enough voltage at the output??

ericgibbs · 20th July 2008, 12:58 PM

Quote:

Originally Posted by Wond3rboy

i have made a dual power supply i dont understand why i dont get enough voltage at the output??

hi,
The smoothing caps are much too low in value.

Whats the transformer secondary rated at [Volts= ??] and what voltage do you get.?

Hero999 · 20th July 2008, 01:25 PM

The input voltage and frequency is also incorrect.

The mains in the US is 60Hz and most simulation programs accept peak voltages, not RMS voltages so you should enter 120√2 = 169.7V rather than 120V.

Roff · 20th July 2008, 03:30 PM

Quote:

Originally Posted by ericgibbs

hi,
The smoothing caps are much too low in value.

Without loads, 150nF is sufficient. Not very useful, though.

ericgibbs · 20th July 2008, 03:33 PM

Quote:

Originally Posted by Roff

Without loads, 150nF is sufficient. Not very useful, though.

hi Ron
Did you notice the 1Hz freq.?

Roff · 20th July 2008, 03:37 PM

Quote:

Originally Posted by ericgibbs

hi Ron
Did you notice the 1Hz freq.?

No. The power transformers in Pakistan must be
HUGE.

audioguru · 20th July 2008, 04:14 PM

If you get mains hum in Pakistan they you will be slowly shaken to death.

Hero999 · 20th July 2008, 04:21 PM

But at least you won't be able to hear the fundermental, just the +20th harmonic which won't be very loud.

Imagine how large the 1F filtering capacitors and power transformer would be.

Wond3rboy · 23rd July 2008, 08:22 AM

Quote:

Originally Posted by Roff

No. The power transformers in Pakistan must be
HUGE.

thanks for enlightening us about this point!!
i tried increasing the capacitor values but than the output voltage decreases.

about the freq this is just done on the simulator which for some reason gives an error when operating with high freq.

ericgibbs · 23rd July 2008, 10:05 AM

Quote:

Originally Posted by Wond3rboy

thanks for enlightening us about this point!!
i tried increasing the capacitor values but than the output voltage decreases.

about the freq this is just done on the simulator which for some reason gives an error when operating with high freq.

hi,
You must simulate with the correct frequency. 50Hz or 60Hz
Using 1Hz will not work correctly.

Wond3rboy · 23rd July 2008, 04:59 PM

now it gives a output of 4v on each side but when i increase the capacitor values than it again gives an error.why is that happening?

ericgibbs · 23rd July 2008, 05:39 PM

Quote:

Originally Posted by Wond3rboy

now it gives a output of 4v on each side but when i increase the capacitor values than it again gives an error.why is that happening?

hi,
I assume we are talking about a simulated power supply.???

What secondary voltage have you set the transformer to.?

Is the simulation allowing 50/60Hz for the Vac input.?

What 'error' does the simulator report.??

Hero999 · 23rd July 2008, 06:01 PM

I wouldn't recommend Electronics Workbench, it's very flakey.

I managed to get it to work after a lot of playing around.

Read the "Time Step Too Small" error section of the help file.

Use LTSpice, it's free (as in price) and much better too.

It doesn't come with a centre tapped transformer model but I'm sure you can find one on the Internet.

Wond3rboy · 24th July 2008, 06:30 AM

yeh i norm,ally sue ltspice but didnt use it because of the unavailibility of the centre tapped transformer

ericgibbs · 24th July 2008, 07:02 AM

Quote:

Originally Posted by Wond3rboy

yeh i norm,ally sue ltspice but didnt use it because of the unavailibility of the centre tapped transformer

hi,
Just for simulation, why dont you configure [ltspice] using two identical transformers, with their own FWB [full wave bridge]?

One with the -V as ground [0v] and the other with +V to ground.. link the grounds together.

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20th July 2008, 01:25 PM	(permalink)
Hero999	The input voltage and frequency is also incorrect. The mains in the US is 60Hz and most simulation programs accept peak voltages, not RMS voltages so you should enter 120√2 = 169.7V rather than 120V. __________________ I also post at the following sites: http://www.stop-microsoft.org http://www.heated-debates.com Screen name: Aloone_Jonez

20th July 2008, 04:14 PM	(permalink)
audioguru	If you get mains hum in Pakistan they you will be slowly shaken to death. __________________ Uncle $crooge

20th July 2008, 04:21 PM	(permalink)
Hero999	But at least you won't be able to hear the fundermental, just the +20th harmonic which won't be very loud. Imagine how large the 1F filtering capacitors and power transformer would be. __________________ I also post at the following sites: http://www.stop-microsoft.org http://www.heated-debates.com Screen name: Aloone_Jonez

23rd July 2008, 04:59 PM	(permalink)
Wond3rboy	now it gives a output of 4v on each side but when i increase the capacitor values than it again gives an error.why is that happening?

24th July 2008, 06:30 AM	(permalink)
Wond3rboy	yeh i norm,ally sue ltspice but didnt use it because of the unavailibility of the centre tapped transformer