transformer...

benmanf · 26th May 2004, 01:30 PM

how do i measure the power or the "Va" of my transformer?

(35V transformer, looks powerful...)

benmanf · 26th May 2004, 03:28 PM

in the schemic of the power supply(P3A) there are 3 wires from the transformer(-35, GROUND, +35) but i have only 2 wires coming out from the transformer... what can i do?
how should i connect it?can i?

jaycee · 26th May 2004, 05:57 PM

You cannot use the transformer unless it has 2 seperate secondary windings, or a centre tap (3 wires). You will be unable to generate both the negative and the positive voltage with only one tap.

sss · 26th May 2004, 06:06 PM

Quote:

Originally posted by jaycee
You will be unable to generate both the negative and the positive voltage with only one tap.

actually its possible to do that , but it would be much better to use a ct transformer

benmanf · 26th May 2004, 06:08 PM

and...how can i do that?

is it complicated?

jaycee · 26th May 2004, 07:51 PM

how is it possible ?

HDTVman · 26th May 2004, 08:43 PM

Quote:

Originally posted by jaycee
how is it possible ?

You build a full wave voltage doubler and refference ground to the point between the caps.

ChocoHolic · 26th May 2004, 09:15 PM

Well, the following voltage doubler does generally work.
BUT for power applications this is a poor choice!
The caps are only charged once per AC-cycle, while the
standard full bridge rectification charges the caps two times per
AC-cycle.
If we charge less often and have longer time between the charging, then we get the following drawbacks:
1. Voltage ripple of the rails increases.
2. Ripple current load of the caps becomes high.
3. In relation to the power, the current peaks in the diodes
and the transformer are unfortunately high.

Bye
Markus

jaycee · 26th May 2004, 09:20 PM

Ahh... I'm still learning

Yeah I can immediately see the high ripple this would have. Not really good for an amplifier!

sss · 26th May 2004, 09:21 PM

Quote:

Originally posted by ChocoHolic
Well, the following voltage doubler does generally work.

thats what i was talking about
ps

benmanf
i have recieved an email from u but i cant reply because yours is not working

26th May 2004, 01:30 PM	#1
benmanf diyAudio Member Join Date: May 2004 Location: Northern Israel	transformer... how do i measure the power or the "Va" of my transformer? (35V transformer, looks powerful...)

26th May 2004, 03:28 PM	#2
benmanf diyAudio Member Join Date: May 2004 Location: Northern Israel	and another question... in the schemic of the power supply(P3A) there are 3 wires from the transformer(-35, GROUND, +35) but i have only 2 wires coming out from the transformer... what can i do? how should i connect it?can i?

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26th May 2004, 05:57 PM	#3
jaycee diyAudio Member Join Date: Apr 2004 Location: Norwich, UK	You cannot use the transformer unless it has 2 seperate secondary windings, or a centre tap (3 wires). You will be unable to generate both the negative and the positive voltage with only one tap.

26th May 2004, 06:08 PM	#5
benmanf diyAudio Member Join Date: May 2004 Location: Northern Israel	and...how can i do that? is it complicated?

26th May 2004, 07:51 PM	#6
jaycee diyAudio Member Join Date: Apr 2004 Location: Norwich, UK	how is it possible ?

26th May 2004, 09:20 PM	#9
jaycee diyAudio Member Join Date: Apr 2004 Location: Norwich, UK	Ahh... I'm still learning Yeah I can immediately see the high ripple this would have. Not really good for an amplifier!

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