Who wants +/-15 and +5 triple secondary toroids?

Bulk Orders
1

I’m looking into a batch of custom wound toroidal transformers for the MB-808 project - they’ll have dual 15V secondaries to provide +/-15V for the analog section PLUS a 5V winding to be used for the digital section.  That way, we won’t have to chain a 5V regulator after the 15V section, and it should be fine for devices that require +/-12V and +5V too…

So far, the minimum quantities for custom windings are large (500x) or expensive ($50), so I’m hoping that I can drum up enough interest to go for the quantity and get them at a better price.  Here’s the group buy sign up link:

http://www.midibox.org/dokuwiki/dougwellington_transformer_bulk_order

EDIT: the info is on the wiki page, but just to clarify, there are dual inputs to handle both 110V and 220V…

2

Yummy.

Why custom wound? Surely such a thing already exists?

Edit: is there any point in making it 7V and using a vreg? I know toroids are nice and clean, but I’m thinking about voltage spikes…

3

a toroid like this could make a nice C64 psu replacement too!

4

i guess weight of toroid shipment will leave lot of overseas builders out of this batch?.. otherwise seems pretty handy.  :-[

5

What are the actual AC voltages being aimed for on the secondary side?

6

I’d probably be interested :slight_smile:

any more details also on the Ampere rating etc? I guess for bigger projects like what I’d use them for, at least 1A on the 15V and 1.5A on the “5V” would be cool.

for the 5V rail, a transformer voltage of 7.5V would be perfect.

S

7

Why custom wound? Surely such a thing already exists?

Thats what *I* thought…  Haven’t found one yet, and I have…(looks)…eight toroid manufacturers on my contact list so far…  Lots of dual secondary stuff out there…

8

i guess weight of toroid shipment will leave lot of overseas builders out of this batch?

I don’t have an exact weight yet, but I think it will be about 450g.  I’ll be happy to ship anywhere…

9

any more details also on the Ampere rating etc? I guess for bigger projects like what I’d use them for, at least 1A on the 15V and 1.5A on the “5V” would be cool.

for the 5V rail, a transformer voltage of 7.5V would be perfect.

May I suggest 2-3A and 8V? I’m thinking about lots of LEDs…

10

OK, well, without getting into the whole Root Mean Square thing…  :wink:

The idea is to be able to provide enough power to work with the regulators we’re using in the MB-808 - 2A for 5V and 15V and 1.5A for -15V.  For reference:

[table]

[tr][td]

+5V

[/td][td]L78S05CV[/td][td]http://www.st.com/stonline/books/pdf/docs/2148.pdf[/td][/tr]

[tr][td]

+15V

[/td][td]L78S15CV[/td][td]http://www.st.com/stonline/books/pdf/docs/2148.pdf[/td][/tr]

[tr][td]

-15V

[/td][td]L795CV[/td][td]http://www.st.com/stonline/books/pdf/docs/2149.pdf[/td][/tr]

[/table]

I’m also planning to put together a standard power supply circuit board that I can put in my various projects.  Stay tuned for another group buy!  ;D

11

Yeh I know the theory, but the practice around here has contradicted it… If it outputs the above specs, it’l all good :slight_smile:

12

Im interested too.

I tried to find something similar a few months back to repair a synth, but couldnt find anything.

R

13

i would also be very interested .  :slight_smile: probably more than one

though i havent figured out what my final likely power requirements

are going to be . 48 modules and counting  :-\

14

I don’t have an exact weight yet, but I think it will be about 450g.  I’ll be happy to ship anywhere…

thought it to be heavier… if it’s under 1-2kg that’s perfect i’d say, not less  :wink:

recently got custom +/-18v transformer for klee, weight shows about 1.5-2kg i guess

15

I recently found these (http://www.toroid.com/standard_transformers/rectifier_transformers/rectifier_transformers_mult.htm)and ordered one for my midiboxFM project. Unfortunately, work has gotten really busy since then and I haven’t had a chance to try it out yet, but I think it’s going to work. It was expensive but it is really nice quality and they shipped fast.

16

i need a couple of these for my MBFM and my MBAY! ;D  i’m interested if the price is right!

17

I’m probably interested in a couple if the price and postage is right. I’ve put my name on the list to show an interest but would need to know the price (postage) before I commit.

I’d also appreciate some advice on how to wire them up because I’m scared of have respect for mains electricity.

          G

18

I’m probably interested in a couple if the price and postage is right. I’ve put my name on the list to show an interest but would need to know the price (postage) before I commit.

I’d also appreciate some advice on how to wire them up because I’m scared of have respect for mains electricity.

Same to all,

Asaf

19

sorry to hi-jack, but if i were to use this for the MBFM project, would i just not use a V-reg on the core since this trafo already puts out +5v?  i assume +/_ 15V is just fine for the OPL3 module etc…  just curious about the +5V rail.

20

sorry to hi-jack, but if i were to use this for the MBFM project, would i just not use a V-reg on the core since this trafo already puts out +5v?  i assume +/_ 15V is just fine for the OPL3 module etc…  just curious about the +5V rail.

the xformer outputs 5vac, you still need to rectify and regulate it…

i’m not sure the opl can take ±15v, but current draw is low enough you should be ok with feeding 12v regs from this xformer…

btw, doug, i have had issues w/ using a 7vdc wallwart on the midibox core, which is what you should get from 5vac * 1.414

if it is rated at a higher current than you pull, it could be ok, but it is cutting it a bit fine for the usual 7805…