I was searching for information on how to "roll your own" OPT for EL84 in push-pull, not for HIFI use (which by the way found one but it has a 7 layers of interleaving which for guitar amp I think it's overkill).
Also searched for 6V6 and "Fender Princeton" which might work for EL84 as well and pretty much NOTHING was found.
Only one site which I can't find at the moment posted some instructions and it was something like:
Primary= 1500 + 1500 turns .16mm wire
Secondary= 100 turns .7 wire for 8ohms and 36+ turns for 16ohms.
winding half primary, half secondary, half primary, half secondary
using 1 x 1 inch core .014 lamination.
I know there are some software to make very accurate designs but .. you know EL84 in pp for guitar, can't think of anything more ordinary and yet seems to be little straight forward data on how to make your own. I'm not trying to invent the wheel
it is not possible for me to buy ready-made from Hammond, Lundhal etc.. that's why I'm asking here.
Also searched for 6V6 and "Fender Princeton" which might work for EL84 as well and pretty much NOTHING was found.
Only one site which I can't find at the moment posted some instructions and it was something like:
Primary= 1500 + 1500 turns .16mm wire
Secondary= 100 turns .7 wire for 8ohms and 36+ turns for 16ohms.
winding half primary, half secondary, half primary, half secondary
using 1 x 1 inch core .014 lamination.
I know there are some software to make very accurate designs but .. you know EL84 in pp for guitar, can't think of anything more ordinary and yet seems to be little straight forward data on how to make your own. I'm not trying to invent the wheel
it is not possible for me to buy ready-made from Hammond, Lundhal etc.. that's why I'm asking here.
Not too many time ago, I used a center tapped toroidal power transformer (110V + 110V to 12V, rated 50W) from lightning, with a couple of ECL82's, it worked pretty fine. The EL84 needs a higher load impedance, near 11KΩ and these kinds of trafo will not work so pretty. It is an idea only.
A pair of EL84 run in push pull AB1 pentode connection with 250-300 plate and screen volts for 18 watts uses 8k P-P primary impedance. See page 2 of this data sheet: http://www.mif.pg.gda.pl/homepages/frank/sheets/129/e/EL84.pdf
The costs due to weight, for the shipping to my country + taxes make you want you use anything before considering importing one of those. Thanks anyway, not a bad source for people located in EU.
I will be using a 20 watt 100volt line transformer for mine. I bought 10 used ones for $2.50 off eBay. I will adjust B+ and bias to suit the trafo, rather than vice versa.
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More info on djgibson51 suggestion of using 100V line transformers.
Cheap Output Transformers
Cheers,
Ian
Cheap Output Transformers
Cheers,
Ian
I've tried rewinding an E frame transformer and shorted the input to the frame. Bleah.
Televisions post 1990 are full of big toroid transformers for switcher power supplies. If I had to wind something I would try to do it on one of those. Round corners, big hole, made for fumbly fingers. and here in the states dead TV's are all over the curb as the city tries to avoid picking them up. The high frequencies used in switchers mean the material of the toroid doesn't absorb too much HF internally.
Watch out touching the display tube back, before safely discharging the electrolytic caps with and insulated handle tool.
While recycling, look at salvaging the transistors on the horizontal board or color board. That is the only way I can source VAS transistors; no distributor other than the E-bay pirates stocks ~200 v high Ft low Cob transistors with heat tabs stocked all over Europe with 2sc 2sa numbers. MJE340/350 is the best there is new here in the US, with no Cob or Ft spec at all.
I picked up power supply boards from a dead LED television last summer, it has even better toroids. The heat sink extrusions were what I wanted, and the fets may someday be pretty useful, too.
For magnet wire dead motor field coils are full of it. And for the fat wires the stuff on the switcher transformer is there already.
Best of luck.
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Look that those switching transformers are made of ferrite cores, then the permeability and the max flux is lower than iron laminated or rolled.
indianajo, possibly you had the best intentions to help people out, and I don't mean to be rude but, from the title of the thread and reading your response, we might start to derail it. Thank you.
So, nobody in diyaudio "instruments & amps" have ever diy an output tranny for EL84 or 6v6, wow I must have asked for the formula to turn dirt into gold or something 😕
I think you answered your own question when you said in your first post "you know EL84 in pp for guitar, can't think of anything more ordinary and yet seems to be little straight forward data on how to make your own." It's because they are so common and ordinary. It's easy for most of us to find a decent used one from an old organ or PA amp or to just buy a new one if we're building for a client since they are paying, so why make one when they are readily available?
Here in the UK; I priced up winding my own transformers (power and output) and it worked out more expensive than just buying an off the shelf model.
Also remember that an OT simply reflects secondary impedance back to the primary. So if you can scrounge up a 4k P-P OT, you can double the connected load for the rated secondary impedance and it will then it will reflect 8k back to the primary. The best one to do this with is a multi-tap secondary. You have the option of hooking an 8 ohm load to the 4 ohm tap or 16 ohms to the 8 ohm tap. These multi-tap OTs were common in old PA amps. Usually the 4k is used for a pair of 6L6s or EL34s or a quad of EL84s. Either way, you will be covered in the wattage handling department for just the AC 15. The extra iron should give you great bass response as well although you might not want that with the AC 15 build.
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I've been using these for my 6V6 Git Amps.
86PP output transformer
Medium Quality HiFi trannies. Suit Guitar Amps well.
10K with 23% UL taps which you can just ignore or use if you want.
23% UL gives max power (rather than the more usual 43% for min distortion) with EL84.
23% UL is ideal for 6V6.
For the price I don't see the point (other than personal satisfaction) for widing your own.
Cheers,
Ian
86PP output transformer
Medium Quality HiFi trannies. Suit Guitar Amps well.
10K with 23% UL taps which you can just ignore or use if you want.
23% UL gives max power (rather than the more usual 43% for min distortion) with EL84.
23% UL is ideal for 6V6.
For the price I don't see the point (other than personal satisfaction) for widing your own.
Cheers,
Ian
WHAT price?
China price? But neither of you lives in China 😉
Australian price? (please quote the at-your-door price for comparison)
VMUNIX lives in ARGENTINA 😎
Let´s check alittle door to door price:
*China FOB price (FOB meaning Free On Board and usually taken as the stuff being loaded on a truck at Factory door)= 18 U$
* EMS (cheapest) shipping price to Argentina= U$38
DHL or FedEx is usually twice as much 😱
* Buenos Aires Customs office CIF price: (Cost Insurance Freight)=18+38=56 USD
That´s inside the Customs building, so to actually be able to bring it home, customer must pay fixed Customs Tariff of 60% (which luckily includes 21% IVA (VAT) and 5% Ingresos Brutos (Sales Tax ) so it´s not as high as it seems.
Raw Tariff is only 20% , max allowed by Gatt and similar Trade agreements.
* so customer must pay CIF value x 1.6= 56*1.6=90U$.
Add to that Customs building "admission fee" around 8$ and 2 way Taxi or expensive parking inside Customs area, plus 6 to 8 hours wait time (there´s a *crowd* waiting in line for their EBay bought pendrive/tennis shoes/ embroiderd baseball cap/etc.) and cheesy Chinese transformer costs well over 100U$ .
Still think the same about "just buy one and ge done with it"?😀
Now given the real world situation, you see it pays to buy the real thing, a good Hammond or Classictone one, which will end up costing about the same and is way better quality.
It also allows a local small manufacturer (ahem !!! .... among others yours truly
) to earn a decent living making amps, transformers, speakers, reverb tanks and other stuff , for own use and resale .
WHAT price?
China price? But neither of you lives in China 😉
Australian price? (please quote the at-your-door price for comparison)
VMUNIX lives in ARGENTINA 😎
Let´s check alittle door to door price:
*China FOB price (FOB meaning Free On Board and usually taken as the stuff being loaded on a truck at Factory door)= 18 U$
* EMS (cheapest) shipping price to Argentina= U$38
DHL or FedEx is usually twice as much 😱
* Buenos Aires Customs office CIF price: (Cost Insurance Freight)=18+38=56 USD
It also allows a local small manufacturer (ahem !!! .... among others yours truly
That's right been there done that, and the final price for items around 30/40 dollars is always over 100 at your door. Winding your own about $ 15 + some of your time.
yup! got inspired by JMF visiting his workplace the guy make his own power transformers go figure.
Thanks djgibson51, I'll be checking that.
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