Pcb transformers. Rectification doubt

[gtangas]

Hi

I want to build a power supply unit with several exits and with several voltages

I know that after the rectification the voltage will drop, for instance a 12v ac will drop to 9..v

But my doubt is the ma

Will they drop?

Thx

[Thomas_H]

I know that after the rectification the voltage will drop, for instance a 12v ac will drop to 9..v

Voltage will increase after rectification, not drop!

Doing the wrong thing will kill you, so you may want to rethink what you are doing.

[RobA]

Hi

I want to build a power supply unit with several exits and with several voltages

I know that after the rectification the voltage will drop, for instance a 12v ac will drop to 9..v

But my doubt is the ma

Will they drop?

Thx

The voltage you get out of rectification and filtering depends on the type of rectification you do. If you do a bridge rectifier, then the output voltage is approximately sqrt(2) x Vrms - 2 * Vfd, where Vfd is the forward voltage drop of the diodes you are using (or just the voltage drop of the bridge rectifier if you use one of these).

If the transformer were ideal, then the power on one side of the transformer would be the same as the power on the other side. You can use this to get an idea of the power requirements of the transformer. But, it is a bit more complicated than that. For instance https://en.wikipedia.org/wiki/Inrush_current.

If you are using mains voltage, you really do want to be careful. Learn as much as you can about how this all works. This site has a section on power supplies that's a good start,
http://sound.westhost.com/articles.htm.

[gtangas]

I know that after the rectification the voltage will drop, for instance a 12v ac will drop to 9..v

Voltage will increase after rectification, not drop!

Doing the wrong thing will kill you, so you may want to rethink what you are doing.

Come on Thomas.... I promise that I will use rubber gloves hehehe
I'm not a tech guy but i know what I'm doing.... As a child me and my brother use to plug the 9v toys to the 220v... It's was fkg amazing hehehe that's where I learn to mess around with AC current hehehe

Hi know by experience that using bridges the voltages drop.... And when we see the schematics from tube amps its obvious that using diodes the voltages increases...

My doubt is to the A

[davent]

Summary of your options here.

http://www.hammondmfg.com/pdf/5c007.pdf

[gtangas]

This is Wath I have in mind

http://www.banzaimusic.com/Hahn-BVEI4221225.html

It's from Germany and I'm from Portugal...
With this Trafo and using a bridge I will get a little more than the 9v... But I need the (+/-) 200ma

The idea is follow the spider schematic...

[RobA]

As long as you put regulators on the outputs, then the 12V should be OK. If you don't regulate it, you are going to see more like 15V on the outputs. On my bench supply that I made using a 12VAC transformer and LM317 regulators, I can adjust it up to 15.25V output. If you went to using an LDO regulator, you would probably be able to get by with a 9V transformer.

If you look at this page, they have recommendations for transformers for various output voltages and schematics and layouts as well. These transformers won't work for the current draw that you want, but they can give you an idea for the other parameters and how the layout works.

[gtangas]

On the past and Using a 15v transf I did a small circuit for powering the lil water amp and the result was a silent 12v supply...
Same like this SCH
12v Trafo>bridge>cap 220uf>reg 9v>10uf and 10pf >out put
I could use diodes like 1n4007 but for simplicity and space the rect bridge was/is the option
From banzai I can buy several trafos with differentiated ma and isolated exits and then get several exits

[Thomas_H]

You are on the right track.

I have a single sided layout for the regulator part in here: http://diy.thcustom.com/?wpdmact=process&did=Mi5ob3RsaW5r
but is has diodes, no rectifier.

[gtangas]

Hey Thomas

Nice board.... That's the idea :-) the only difference from my inicial ideia is the diodes..

And what about the amperage?
Will the amps of the Trafo change after the rectification? Because this is my main doubt...

I can use the diodes in order to avoid a higher voltage Trafo but i want to keep the amperage of the secondary

[Thomas_H]

The mA you can get out of the regulator will be almost equal to what the trafo is providing on its secondary.
No worries with that.

[gtangas]

Ok Thomas

Thanks for the help... And I just want to say that I received your warning about high voltage with a smile... I understand the concerns of dealing with theses voltages that so many times we forget of.

As we say in Portugal Grande abraço
Sérgio

[rullywowr]

I know that after the rectification the voltage will drop, for instance a 12v ac will drop to 9..v

Voltage will increase after rectification, not drop!

Doing the wrong thing will kill you, so you may want to rethink what you are doing.

Come on Thomas.... I promise that I will use rubber gloves hehehe
I'm not a tech guy but i know what I'm doing.... As a child me and my brother use to plug the 9v toys to the 220v... It's was fkg amazing hehehe that's where I learn to mess around with AC current hehehe

Hi know by experience that using bridges the voltages drop.... And when we see the schematics from tube amps its obvious that using diodes the voltages increases...

My doubt is to the A

I found a picture from your childhood...

[gtangas]

Hhehehe certainly we are looking at a future tech guy or a fried kid.... But honestly at the time my grandfather worked at customs and we always received electric cars and stuff like that.. I'm 40 now, and we use to connect wires from the batteries and plug it to 220v... For a second it was cars on nitro... Hehege and after that...a furious father... Hehehe

Enviado de meu AT10-A usando Tapatalk 4