/diy/ - Do It Yourself

If it's 30V 3A means it's 90W, you can get 6A out of it but that would be 180W and you would burn it.
The TF works on full power normally anyway. The winding that's not in use doesn't limit your power or current.

>>1372954
Well if i use both taps then its 60V 3A, thats 180W

>>1372913
No.

>>1373206
>if i use 2 full bridge rectifiers i would short 2 diodes at each half of sine wave (at least i think)
you showed me that right? By using center tap rectifier i can only get 90W right?

>>1373209
I assume that is the circuit you intend. As you can see, there are two loads at different voltages. I don't think it will combine well into one load for you.

>>1373210
Thats what i was thinking, i was kinda hoping to get those loads somehow in parallel so i would get 30V but 6A :/. Seems its impossible without having separate coils.

>>1373215
There are some tricks using switches and caps to isolate voltages, but I don't think you're going to get the full 6A, and you'd be better off getting the right transformer than trying to build something fancy. Maybe see if there is an off the shelf DC to DC converter that goes 60 to 30 V that will meet your needs.

>>1372913
>Is there any way i could get single rail voltage but twice the current out of center tapped transformer?
Yes. Ignore the center tap and use a buck-down to convert 2V*I to V*2I.

>>1373217
>>>1373231

I have DC-DC converter but it can only go to 60-65V, i get 80V at filtering caps so that wont work, i guess im just gonna get different transformer

again
it's a 90W TF, you can't (shouldn't) run it on 180W, how hard is it to understand?
it doesn't matter how you wire it, it's still 2x more than allowed power
it probably has a temp fuse that will just burn out

>>1372913
You could look into wiring it in an auto transformer configuration. That would increase the power you can transform with it, but I'm not sure by how much

>>1373237
It's a 180va transformer if it's a 60v (30+30) at 3 amps

>>1373254
depends if it's build for center tapping or not, OP should check spec first, these faggots never provide proper info

check how much watts the tf is for

>>1373255
I said its +-30V, i even said i have 2 connected coils (basicaly one coil with center tap out)
Its 200VA transformer, has +-30V and +-32V but they are both at around 3A
>>1373259
It says max power 300W on input, but its 200VA on secondary +-30V, and rest is on separate 12V coil, probably 3A

>>1373255
>out of center tapped transformer?
>+-30v central tapped transformer
>Considering i have +-30V and 3A transformer

>>1372913
You can get any amperage you want the question is, for how long? A transformer is designed with a specific maximum wattage, exceeding that will damage it (overheat and cause shorting).

If you want more amps, get a bigger transformer, or use a switching power supply rated for a specific amperage.

not sure where you get that +- 30v transformers only output positive voltage, so what is it a 15v center tapped for a total of 30v, or 30v center tapped for 60v?

>It says max power 300W on input, but its 200VA on secondary
then you can draw 30V 6A from it, especially with a center tap rectifier

>>1373467
actually, you will get 20.86 vdc with a center tap rectifier.

>>1373473
and 41.72 vdc with a bridge rectifier.

the 3A should be for continuous use but for the rectifier you use the winding only for half the time (period) so 6A should be OK

>>1372913
pull out the center tap, separate the coils, put them in parallel, feed diode bridge

>>1373502
>I don't know how transformers are made

>>1373432
Its 30V center tapped, i said that in 3rd response, seems like im gonna get different transformer or smps
>>1373473
>>1373474
Im getting 40V with center tap rectifier and 80V with full bridge after filtering caps

>>1373502
THIS. definitely.
What kind of transformer do you have ?
Toroid ? E/I ? C ?
Chances are that only by removing the protective adhesive you will actually see the two wires of both secondaries being attached at CT point.
Just segregate über an unter coils, use ohmeter to determine which coil they belong to, then parallel both coils so you get 15V/6A.

Also show pic of trannie

>>1373206

>>1374011
https://www.njuskalo.hr/image-w920x690/elektronski-uredaji/transformator-12v-30v-35v-slika-96541636.jpg
https://www.njuskalo.hr/image-w920x690/elektronski-uredaji/transformator-12v-30v-35v-slika-96541639.jpg

Its from an old amplifier, i can see 2 wires going to that PCB, im gonna desolder it and do some testing now, gonna post results soon

>>1373941
so that means you have a 60 volt center tapped transformer NOT a 30 volt.
it also means you have a 3 amp transformer based on the wattage rating.

>>1374011
Honestly cant believe this isnt first thing i should have done, you just saved me few bucks.
I matched coils polarity, put them in parallel and just used full bridge rectifier, still have to make some sort of 6A 30V load so i can test if for few hours to see if it will work fine, but i dont think there should be problem with it

>>1374167
dude, measure that wire size and look up the amp rating then derate by 20% if that transformer is rated at 3 amps it's 3 amps for everything not just those winding's.

>>1374170
All windings are 3A rated, that means that at highest voltage (64V) its 180W, which responds to 200VA rating, maybe even more, so even if i use only 30V i can still get maximum of 3A from those same wires, if i put them in parallel i would have twice the wire thickness so amperage should go up, primary wattage dictates power on secondary, at least what i understand

>>1374172
that transformer came out of a Technics stereo

The wire pinouts are Black and brown wires 11.6v red and brown 32.6v gray and brown 28.2v yellow and brown 28.3m and blue and brown 32.6.

there is no ratings in the service manual for the transformer so the only way to get an idea of the maximum amps is to measure the output wires and look up their ratings.

>>1374172
how your transformer is wired.

>>1374172
op, i have to show my gratitude
you actually did something and posted results
that makes you better than 95% of the other threads

>>1374182
I found somewhere on internet it should be 200VA, only thing i found in manual is its rated 296W max power, amplifier was 2x55W so considering amp efficiency is around 50% i guess it would be around that 200VA
>>1374185
Yes, its one coil with few taps for output
>>1374188
No problem :)

>>1374215
>>1374185
Also with 3A light bulb voltage dropped close to that 28V its rated at after filtering caps

Thanks everyone, i tested it with 24V motor and resistor and it drops to 28V when drawing 5.5A continuous, not sure how much more would i draw without damaging or overheating transformer but im gonna need less than that anyway.

>>1374172
I gotta ask, is that scope a kit?

>>1374167
>>1374172
The only pics of trannies that /diy/ like <3

>>1374316
Seems legit. You might also test it with a 3 car bulbs wired in serie, without rectifier, so it makes a 36V/6A-ish pure resistive charge. Bulbs might not light very much, but if nothing explode/fuse at this point, consider you're safe.

>>1374215
the stereo in question is rated for that output, your windings are not, measure the size of the wire and post it here.

>>1374384
Yes, i added 2 lithium batteries to power it up and used 10x probe>>1374392
>>1374392
I tested it for 2 hours and thermal fuse didnt blow, transformer was warm but nothing to be concerned i think
>>1374570
Im not at home right now but i think its about 1-1.5mm in diameter, not sure what gauge is that, but windings didnt get hot when i tested it for 2 hours