In this AM/FM cassette-corder, the ripple filter Q305 gets 9 VDC from a power supply (the red line going to the right).
In this application, is there any particular reason that the collector of N-P-N transistor is connected to 9 V? What would happen (in theory) if I swap the more negative emitter (8.2 V) with collector?
How this transistor is connected, is it a common base scheme?
In two words, how ripples are being filtered?
Thanks!!

 

If you swap the emitter with the collector then you are running the transistor in its reverse active mode. It will still behave like a transistor, but a very poor one with very low gain. The transistor construction is generally highly asymmetric in order to get desirably properties, which generally include high gain and also high breakdown voltage between on the normally reverse biased collector-base junction.

 

If you swap the emitter with the collector then you are running the transistor in its reverse active mode. It will still behave like a transistor, but a very poor one with very low gain. The transistor construction is generally highly asymmetric in order to get desirably properties, which generally include high gain and also high breakdown voltage between on the normally reverse biased collector-base junction.

Much appreciated! I guess "highly asymmetric" is the key word. Thanks!