Can someone pick me a transformer? (TDA2050)

[Jidis]

I hate to ask this big of a favor, but I'm in a pinch for time-

I built a pair of TDA2050 circuits to power a couple 4-inch full range speakers for watching television (for my father actually). I'm having trouble picking out a transformer. I'm trying to get a Digikey order in by Monday, so whatever they've got would be ideal, but if necessary, I could go with somewhere else if shipping isn't too high.

The suggested spec where I got the rest of the circuit was "A toroidal transformer with dual 18 Volt secondaries and rated at 120VA (3.3A per secondary)". When I limit the search criteria at Digikey to that stuff, I turn up nothing.

Here's the catch- I'm suspecting that most of the people building by those suggestions are going for maximum output as well as optimum sound quality. It's possible that I won't need either of those (definitely not the first one). I'll be pushing one 4-inch,4-ohm driver per amp, with a nominal power spec of 40W each. They'll also probably be at very close range and I'm looking for more of a mid/high bite than any heavy low frequency output.

If anyone has an idea on whether or not to go lower or what to change on the specs, and ideally a specific reasonably priced part I could order, it would be a huge help.

Thanks for reading, and sorry to beg.

George

[wahab]

2 X 18 V ac is too high, the tda2050 is rated at +-25V..
the rectified voltage with your transformer will be within extremum..
better to use a 2 X 15 V AC transformer..

[asbus]

Hi,

I've been using a 2x18VAC 80VA to my TDA2050 amp for a couple of months with no failures. I'm also running with 4 ohms speakers.
The sound is incredable good, for that little tiny chip!

Good luck

[Jidis]

Thanks guys!

Wahab (re: a lower power supply)- That's one of the main things I was wondering about, but not so much for the well being of the chips, as just for the fact that I probably don't need anything that loud.

George

[paulb]

You don't need a toroidal transformer. How about this one (Digikey):
237-1279-ND
Digi-Key - 237-1279-ND (Manufacturer - VPS28-1500)

[Jidis]

Thanks Paul!

I'll order that today if nothing else comes up. Not sure I understand the VA ratings though. The page (this) where the circuit was from mentions the recommended 18-0-18 as being 120VA and providing 3.3A per secondary. Why is the dual 14V one at Digikey so much lower (43VA) while doing 3A per secondary, and what's the deal on the dual primary coils on that one?

Thanks!

George

PS- Sort of surprised in all this that many nice loud powered computer speakers and stuff manage to run off little two dollar wall wart transformers, while just to power a small chip amp circuit properly, the lowest you can go is up near twenty bucks. I'm wondering what I would have lost/gained had I gone with a non-split power supply.