Hi guys,

I'm making an class-AB power amp. for school. Calculations and the simulation are done, but I need a pair of complementary transistors. Do you know of some shop that's selling those, accepts PayPal and is shipping worldwide (Yea, I'm kinda picky ) ?

 

Worldwide shipping? Don't you really just need shipping to where you are, which you have not told us?

 

You also didn't specify the transistors, other than the fact that they must be complementary.

 

What kind of transistors is it we are talking about. If you have used some common transistors that your school stock. You can try to do the matching by your self. Here is paper about that http://www.edn.com/design/analog/4407476/Successfully-choose-complementary-bipolar-transistors But I guess any kind of equipment that can measure transistors β may be of help. You could also try your friend Google. They are not that uncommon. And most world wide major components pushers stock such items

 

What kind of transistors is it we are talking about. If you have used some common transistors that your school stock. You can try to do the matching by your self. Here is paper about that http://www.edn.com/design/analog/4407476/Successfully-choose-complementary-bipolar-transistors But I guess any kind of equipment that can measure transistors β may be of help. You could also try your friend Google. They are not that uncommon. And most world wide major components pushers stock such items

A decent class AB amplifier design should not require matched betas in the complementary transistors, assuming the transistors are specified as complementary in the datasheets.

 

since Ron H is watching the thread , I thought I'd ask : How closely matched are a pair of complementary transistors in terms of beta percentages and other important parameters say for an AB amp? I'm assuming that it's easier to manufacture semiconductors to a tighter tolerance than other components .
(I hope i'm not derailing the thread)

 

I said worldwide because I'm from Croatia, and the transistors I was looking for are BD139 and BD140, but it's not like I need exactly those two. I was looking for the STD830CP20 to be honest ...

 

A decent class AB amplifier design should not require matched betas in the complementary transistors, assuming the transistors are specified as complementary in the datasheets.

I was more thinking of going through a stock of non matched transistors to make a matched pair

 

since Ron H is watching the thread , I thought I'd ask : How closely matched are a pair of complementary transistors in terms of beta percentages and other important parameters say for an AB amp? I'm assuming that it's easier to manufacture semiconductors to a tighter tolerance than other components .
(I hope i'm not derailing the thread)

I was talking about an audio amp. A good design should have adequate feedback to correct for beta mismatches, as long as the betas are reasonably high.
If we're talking about an amplifier without feedback, it depends on the design and the performance requirements.

 

Seems I can't send a PM so email these people

http://www.cricklewoodelectronics.com/Cricklewood/home.php?cat=184

They seem to be £0.50 each