Hi guys!🙂
I'm a newbie and I'm trying to learn electronics: if you take a look at the picture of the amp (below), you can notice that every channel is based on three transistors: TIP120/BD135 (in the middle)/TIP125.
Well, I alredy know that the TIP120/TIP125 are complementary transistors (NPN/PNP)...I also know how they work, but I don't understand what role can have the two BD135 in the middle of each pair of TIP transistors.
Could the two BD135 have the function of increasing the amp output power?😕😕😕
Sorry for my ignorance, guys😱! could you explain it to me, please?😉
Thank you in advance for your kindness😉!
Regards🙂
I'm a newbie and I'm trying to learn electronics: if you take a look at the picture of the amp (below), you can notice that every channel is based on three transistors: TIP120/BD135 (in the middle)/TIP125.
Well, I alredy know that the TIP120/TIP125 are complementary transistors (NPN/PNP)...I also know how they work, but I don't understand what role can have the two BD135 in the middle of each pair of TIP transistors.
Could the two BD135 have the function of increasing the amp output power?😕😕😕
Sorry for my ignorance, guys😱! could you explain it to me, please?😉
Thank you in advance for your kindness😉!
Regards🙂
Attachments
Motorola Application Note AN483B
You have the explanation in brief. For further reading refer to AN483B - see attached Google search hit.
You have the explanation in brief. For further reading refer to AN483B - see attached Google search hit.
Attachments
As others mentioned these BD135's are most likely VBE multipliers to bias the output transistor pairs, and they are mounted onto the same heatsink to thermally track the output pairs - so to improve the amp's thermal stability.
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