Headphone amp takes "AC 15V-0-15V"?

[Triode]

https://www.aliexpress.com/snapshot/6595438310.html?orderId=66695753316178

I got one of the above, and see that for power input it has 3 plated through holes labeled AC 15V-0-15V. I'm guessing the AC isn't a mistake because there seem to be plenty of transformers out there that match (though if it's DC these could of course be paired with a rectifier).

Does that sound right? And if so do I just connect a 15VAC output transformer straight to it? And out of curiosity, why would it take AC?

It looks like one like this is meant to go with it:
**broken link removed**

 

[audioguru]

The transformer must be 30V center-tapped which is 15V-0-15V. The transformer you linked says it has only 4 wires but it needs 5 wires.

The horrible translation from Chinese to Engrish shows almost NO SPECS! It says it has the Toshiba TPA6120A but Datasheet Archive never heard of it. Texas Instruments makes the excellent TPA6120A2 headphones amplifier IC.
What are the very old NE5534 opamps used for? Phono inputs?

 

[Triode]

I'm not sure why they put those there. Or what the two switches do. I'd just heard that the TPA6120 was a good digital amp chip. I wonder if the board is just rectifying that power and if I could simply supply DC somewhere else on the board, past that stage. Or if it actually is using AC at the amplifier IC. Which as far as I know would be pretty strange.

 

[KeepItSimpleStupid]

The TDA chip needs a bipolar supply from +-5 to +-15 VDC. A 30 VAC CT xformer will give you about +-21V (1.4*15), so you might see some 7815 and 7915 regulators on the board.

Transformer has NO specs, well it has some upside down ones in the picture. It's not a 120/240 input. It's 240 only. One terminal is labeled SCN or Screen. It's meant to go to ground. Phase does not appear to be marked. It won't work because the primary is not 120 V for your locale.
Phasing for 15-0-15 could be determined easily.

 

[Triode]

Ah, I missed the 240V

Maybe this one would work?

**broken link removed**
It looks like it, but I don't know, do these come with different phasing? It seems like having 2 15V outputs would have no point without them being out of phase.

 

[Triode]

On what may seem like way too big of a trangent for such a small project, I do have some transformer toroids, it seems like making a 15-0-15 wouldn't be that hard. 4 times as many wraps on the input than the output to drop 120 down to 30, and a center tap to split it into 15-0-15. I'm not really sure how you determine what the number in total should be though. Seems like if they fit you could do 200 and 50, or 800 and 200. I'll have to read up on that.

 

[KMoffett]

The transformer must be 30V center-tapped which is 15V-0-15V. The transformer you linked says it has only 4 wires but it needs 5 wires.

The 4 wires probably refer to two 15VAC secondaries.

Ken

 

[Triode]

Actually if I could power it by battery that might work well. If that chip takes +- 5 to 15V then a pair of 9 or 12V batteries applied at the right point might be able to power it. It looks like it has a rectifier bridge right after the input. So really connecting across the input before or after those diodes would probably work, it would just always go through one set of diodes and the others would never be used. Right?

 

[ChrisP58]

On what may seem like way too big of a trangent for such a small project, I do have some transformer toroids, it seems like making a 15-0-15 wouldn't be that hard. 4 times as many wraps on the input than the output to drop 120 down to 30, and a center tap to split it into 15-0-15. I'm not really sure how you determine what the number in total should be though. Seems like if they fit you could do 200 and 50, or 800 and 200. I'll have to read up on that.

Just make sure that your toroids are the right material for 50/60 Hz. The core material for line frequency transformers is very different than that use for high frequency switch mode power supplies.

 

[Triode]

Just make sure that your toroids are the right material for 50/60 Hz. The core material for line frequency transformers is very different than that use for high frequency switch mode power supplies.

Ah, well that I don't know. They're painted blue and come from giant inductors. I have no idea if they are the right material or not.

 

[KMoffett]

Yes, you can use batteries... if the batteries can supply enough current. Place the batteries in series like this: +[ ]-+[ ]- The + of the left battery goes to one of the "AC15V" solder pads on the PCB. The - of the right battery goes to the other "AC15V" pad. The -+ junction of the two batteries goes to the"-0-" pad. You will so need to put a DPST switch between the batteries + and - terminals and the "AC15V pads to simultaneously shut off the power from both batteries.

Ken

 

[KeepItSimpleStupid]

Where do you find these things? or should I say descriptions. There's no input taps on the transformer, but I'll give it 99.9% chance that it will work.

 

[KeepItSimpleStupid]

Ken:

Ignore the description for the first xformer. One of the pics has the schematic upside down and not head-on. Clearly 2 independent secondaries and a primary of 200 and some odd volts and a a label SCN which I would assume means Screen or the short name for Electrostatic Shield.