seeking 36-0-36v (36vct) internal power transformer for eh clone theory

[pinkjimiphoton]

well, i screwed up again, and found what i thought was perfect. about 5x too big tho.

i REALLY don't wanna have to chew this up too much if i can avoid it.

so i need to find the proper kind of transformer... if someone has one they can sell me, or one they can point me at, i'd be grateful.
i only seem to be able to find every voltage but the one i need!

what am i doing? i'm converting a brit 240v clone theory (300 board, the mn3007 classic but in red and black) to 115v to run here.

thanks brothers!!!!!

[theehman]

36vct is 18-0-18v.

This one should work fine.  I've used it on other EH products.
http://www.mouser.com/Search/ProductDetail.aspx?qs=sGAEpiMZZMv4oUrzpPKU3ByqNvysmkwGIQXFwlz1KSg%3d

[pinkjimiphoton]

ron, you are indeed THE WALRUS!!

one quick question tho.... do i have to use  reverse zener diodes or anything to get it down closer to 18v so the 7815 doesn't cook?

edit: i ask this cuz i checked the data sheet for the 7815 and it says max input volt of 23v.... i wouldn't think it would matter, but i want to be sure before i blow up YAVP (yet another vintage pedal) 

sorry for the dumb newb question, but my only real experience with transformers were tube amps many years ago..

thank you sir!!

[Gus]

Does the 240VAC transformer have two primary windings?

[theehman]

one quick question tho.... do i have to use  reverse zener diodes or anything to get it down closer to 18v so the 7815 doesn't cook?

No.  This one is lower voltage than the original so it'll actually run cooler.

[pinkjimiphoton]

Does the 240VAC transformer have two primary windings?

yes gus,
two primary, the guy had hooked up the ground to the dry out ground lug.
i can run it at 115v, but it only puts out 9volts per side instead of the 18v.

my other clone theory is the same board, but in a different package so it made it easy to reconnect everything that had been molested,
and i've got the clock and bbd's from when i built one so look forward to fixing this up. the thought of true stereo clone theorys makes me ....ummm  <looks over shoulder> yeah...

[pinkjimiphoton]

one quick question tho.... do i have to use  reverse zener diodes or anything to get it down closer to 18v so the 7815 doesn't cook?

No.  This one is lower voltage than the original so it'll actually run cooler.

thank you my friend. pulling the trigger now, should have this beauty back to life soon.
i think i'm gonna plug the hole he had in it rather than try to add the clean blend back in.
someone had tried to add a simple buffer to the input and run it to a pot apparently to blend the dry with the wet.

or thinking a footswitch to preset my favorite position on the chor/vibe vibe/flange switch...

ron, did ya ever take one of these and put the switch in the middle, kinda like getting the neck and mid pickups on an old strat with a 3 way p'up switch? in the middle, you get something.... different. it's very flangy and animated, at some positions of the knobs, you can get some amazing "blurb" kinda sounds. this is still my fav eh pedal, even more than the bmp..

thanks bud.

[psychedelicfish]

Does the 240VAC transformer have two primary windings?

yes gus,
two primary, the guy had hooked up the ground to the dry out ground lug.
i can run it at 115v, but it only puts out 9volts per side instead of the 18v.

The reason Gus asked is that you can hook up the 115V mains to only one of the primary windings, rather than both in series, eliminating the need for a replacement transformer.

[pinkjimiphoton]

Does the 240VAC transformer have two primary windings?

yes gus,
two primary, the guy had hooked up the ground to the dry out ground lug.
i can run it at 115v, but it only puts out 9volts per side instead of the 18v.

The reason Gus asked is that you can hook up the 115V mains to only one of the primary windings, rather than both in series, eliminating the need for a replacement transformer.

how would i do that? there's only 2 wires on the primary. there's only the one wire, ultimately in series from beginning to end on the primary, the secondary has the center tap.

i don't think i'm understanding this correctly... sorry~~

[psychedelicfish]

there's only 2 wires on the primary. there's only the one wire, ultimately in series from beginning to end on the primary, the secondary has the center tap.

In that case, there's only one primary winding. If there were four primary leads then you'd have two primaries, or if there were three you'd have a centre tapped primary which would allow you to continue using the existing transformer. It may be worthwhile replacing it with a transformer that has a dual/centre tapped primary and adding an SPDT to switch between mains voltages because then it could also be used overseas (more flexibility for not much extra complexity is always a good thing). I think RS sells some small dual primaried toroidal transformers for pretty cheap.

[pinkjimiphoton]

ahhh... i see, thanks ed.
i ended up ordering the one ron reccomended. if the walrus agrees who am i to argue?

goo goo gu joob... 

[tubegeek]

I think RS sells some small dual primaried toroidal transformers for pretty cheap.

Radio Shack (= USA) ?
or Radio Spares (=UK) ?

'Cause I loves me some little cheap toroids for various purposes. And if Radio Shack is carrying them that's a new one on me, so THANKS! for that info.

goo goo gu joob...

"I am he as you are he as you are me/And we are all together..."

[pinkjimiphoton]

sitting in an english garden waiting for the sun....

awesome!!!!!!!!!!!!!!

[Govmnt_Lacky]

edit: i ask this cuz i checked the data sheet for the 7815 and it says max input volt of 23v.... i wouldn't think it would matter, but i want to be sure before i blow up YAVP (yet another vintage pedal) 

Jimi,

I don't know where you looked but, the LM7815 should have a max recommended input voltage of ~35VDC.

http://www.fairchildsemi.com/ds/LM/LM7815.pdf

[pinkjimiphoton]

greg, i got it from here... top right of the first page, maybe i misunderstood? says 15, beneath it 23.
my bad!

http://pdf1.alldatasheet.com/datasheet-pdf/view/9046/NSC/7815.html

thanks for the headsup!

[PRR]

> top right of the first page, maybe i misunderstood?

Maybe I am misunderstanding? I don't see "23V" *any*where on the first page of the datasheet.

On page _4_ I see a "23V". This table is labeled "Electrical Characteristics".

What you want is *top* of page 3, "Absolute Maximum Ratings".
Input Voltage (VO = 5V, 12V and 15V) 35V

That 23V on the Electrical Characteristics table is a "typical test condition". If you have complete choice of transformer, you would probably put 22V-24V in to get 15V out. They tell you the peak and short current and the temperature coefficient for 23V input.

They don't want to boast about the performance at the full 35V input, because that's unlikely in a well-balanced build, and mainly because the peak and short currents will be *less* with the higher inputs. Short-circuit current at 35V in will probably be 0.5A, which looks a lot smaller than the 1.2A they got at 23V in.

The EH probably never draws even 0.1 Amps. So you don't care.

However inputs much over 24V DC *may* require a heat-sink on the '7815. No problem: build it, put your finger on the 7815, if you say "Ouch!" then cool it better. Especially if the voltage has dropped below 15V.

[psychedelicfish]

I think RS sells some small dual primaried toroidal transformers for pretty cheap.

Radio Shack (= USA) ?
or Radio Spares (=UK) ?

'Cause I loves me some little cheap toroids for various purposes. And if Radio Shack is carrying them that's a new one on me, so THANKS! for that info.

Sorry, I meant Radio Spares. The USA branch for them appears to be called Allied Electronics, but I can't seem to find the transformers available from the NZ branch of RS.