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

[Doug Wellington]

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....

[stryd_one]

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...

[sineSurfer]

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

[Kartoshka]

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

[amp1ron]

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

[seppoman]

I'd probably be interested :)

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

[Doug Wellington]

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...

[Doug Wellington]

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...

[stryd_one]

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...

[Doug Wellington]

OK, well, without getting into the whole Root Mean Square thing...  ;)

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

[stryd_one]

Yeh I know the theory, but the practice around here has contradicted it.... If it outputs the above specs, it'l all good :)

[robwillis]

Im interested too.

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

R

[diablojoy]

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

though i havent figured out what my final likely power requirements

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

[Kartoshka]

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  ;)

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

[baconjuice]

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.

[buhler]

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

[Goblinz]

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

[asafnetzer]

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

[buhler]

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.

[bugfight]

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...

[diablojoy]

just had a re think.while the secondaries sound all good ignoring R.M.S. for the moment. Question for doug you didn't specify voltage supply for the primary

since you are in the US you would of course be looking at 110V which wouldn't suit a lot of people in other countries , or are you already ahead of me and

specifing two primary windings into the design as they are to be custom wound ?

[Goblinz]

just had a re think.while the secondaries sound all good ignoring R.M.S. for the moment. Question for doug you didn't specify voltage supply for the primary

since you are in the US you would of course be looking at 110V which wouldn't suit a lot of people in other countries , or are you already ahead of me and

specifing two primary windings into the design as they are to be custom wound ?

*SLAP*

The proposal is to buy a fairly large quantity of Toroids with not just 110/220V inputs with dual 15V secondaries, but to add in a third set of secondary windings for 5V

*/SLAP*

[diablojoy]

:-[ damn i hate that went over the forum posts half a dozen times looking for that and forgot to re look on the wiki page sorry

[DragonMaster]

Out of my head, Avel Lindberg and Plitron make good transformers.

EDIT: A few more mfg's:

http://www.diyaudio.com/forums/showthread.php?postid=1278098#post1278098

[Echopraxia]

Hey Doug I put my name on the aiting list for the 3rd kit run of MB 808 and its been awhile since I've check up on the site. Do I need to get one for MB 808 on this wiki or are you including this toroid in the MB 808 kits when the time comes?

Also is this good for MB FM and MB 6582 specifically?