Power transformer with multiple voltages

[RuudNL]

I need to (re)build a power supply for a small mixer. (The internal switched power supply already burned out 3 times.)
The voltages I need are:

+ 5  V / ~1 A.  (7805 ?)
+15 V / ~1 A.  (7815 ?)
- 15 V / ~1 A.  (7915 ?)
+ 48 V / ~ 0.15 A. (?)

Are there transformers available that can deliver all four voltages, or do I have to use three different transformers?
I don't like the idea of three transformers in a box, but a custom transformer would probably be more expensive.

 

[zayance]

I need to (re)build a power supply for a small mixer. (The internal switched power supply already burned out 3 times.)
The voltages I need are:

+ 5  V / ~1 A.  (7805 ?)
+15 V / ~1 A.  (7815 ?)
- 15 V / ~1 A.  (7915 ?)
+ 48 V / ~ 0.15 A. (?)

Are there transformers available that can deliver all four voltages, or do I have to use three different transformers?
I don't like the idea of three transformers in a box, but a custom transformer would probably be more expensive.

+5V  LM2576?
+15V  LM317 + Trimmer ?
-15V  LM337 + Trimmer ?
+48V TL783 + Trimmer ?

Maybe better?

 

[JohnRoberts]

Generally the +48 Phantom doesn't require a dedicated transformer winding.  You can make it from a lower voltage winding with a cap doubler ot tripler, or use a step up switcher.

A switching PS can make the 5v and +/-15V from a single winding fairly efficiently. If you prefer to use pass regulators, the 5V will waste a lot of power from a 15+ V rail. back in the '80s is did a trick PS where I used a transistor switch to disconnect the transformer winding when the unregulated supply for the 5V pass regulator was charged high enough.  This was decent efficiency for the low tech approach. These days I would probably just use a switcher all around.

JR

 

[RuudNL]

I would never use the +15 V to make the +5 V, This would indeed waste a lot of power!
That is why I thought about 3 transformers:

18-0-18 V. ~ for the +/- 15 V.
6 V for the +5 V.
2 x 24 V. for the 48 V. (Or maby use a voltage multiplier for the 48 v. from the 18-0-18 ~)

@Zayance: What would be the advantage using these regulators? I have very good experiences with the 78xx/79xx series.

 

[sahib]

You won't get these voltages from an off-the-shelf transformer. Particularly 48V.  We have a custom made for the 511 with 2x16V @ 2.2A, 2x24V @ 2.2A and 1 x 48V @ 150mA but it is about 100mm in diamter and 60mm high. So it might be a bit of an overkill. But if you are o.k. with it then contact Mr Volker the_silent_arts.

However, I have some removed from other equipment and I am sure one of them has 2 x 17.5V and 5V and whole load of other odd voltages. In worst case scenario you may have to do a voltage doubler.

PM me to remind.

 

[ruffrecords]

I have a nice little PCB laid out for a complete +48V phantom supply based on the TL783.

Cheers

Ian

 

[Hank Dussen]

There's this French(?) company that makes custom toroidals that really aren't that expensive.
Anybody remembers this company?

 

[zayance]

@Zayance: What would be the advantage using these regulators? I have very good experiences with the 78xx/79xx series.

Nothing much, just giving suggestions as you were adding question marks next to your choices.
Both will give you what you need anyway, i like the fact that the LM's are adjustable...

As for the french company making Custom toroidals, takes some time (3 weeks at least), but you should check shipping with them as i'm not sure
about that when it's out of France. But you have some other choices here also i guess....

"you have google translate on top of the page"
http://www.audiophonics.fr/transformateur-torique-sur-mesure-toutes-puissances-p-3675.html

 

[RuudNL]

That French company looks very interesting!

 

[zayance]

http://www.groupdiy.com/index.php?topic=42166.msg524408#msg524408

 

[RuudNL]

I asked them if I could pay by Paypal.
The answer was "Yes of course, but you have to order through the e-shop".
OK.
But if I choose a custom transformer, the amount for the transformer is always 1 Euro.
I can add the specifications in the comment field, but I can't change the sum I have to pay for the transformer, making it (as far as I see) impossible to pay with Paypal!

So, I'm completely confused by their website and as far as I see it now, it seems impossible to order a custom made transformer through their e-shop. 

 

[audiomixer]

I think you have to order the 'right' number of 1€ to match your transformer price.... add your specs in the comments - thats what they say on the site.

- Michael

 

[zayance]

I asked them if I could pay by Paypal.
The answer was "Yes of course, but you have to order through the e-shop".
OK.
But if I choose a custom transformer, the amount for the transformer is always 1 Euro.
I can add the specifications in the comment field, but I can't change the sum I have to pay for the transformer, making it (as far as I see) impossible to pay with Paypal!

So, I'm completely confused by their website and as far as I see it now, it seems impossible to order a custom made transformer through their e-shop. 

how to order is written on the page, the idea is that first you make the calculus to get the number of windings and VA you need, then you report the price of it going with the price table they give, if you need a non standard one, meaning low profile or high profile, you'll have to add this on the comments you'll have to give them when doing your order, for example:

Primary:
2x115V

Secondary:
2x18V 1.5A
2x24V 1.5A

6 Windings
63VA
Low profile (99 Diameter , 27 High)

So here the price of this transformer would be 33 Euros. That's what you put in the quantity field when you order.

Beware that it will take easily 3 weeks to 1 month delivery.

T.

 

[RuudNL]

I'm afraid my French isn't what it used to be... ;D
I've read the text in English now and could order the transformer.
Thanks!

 

[zayance]

No prob, curious how much is the shipping to you?

 

[RuudNL]

Too much! (19,10 Eur.) 
But a can't get this transformer elsewhere.