From a salvage piece I have a circuit board with a BD675 & BD676 (Medium Power NPN Darlington Bipolar Power Transistor) together in a (sub?)circuit. I looked up the datasheets and one transistor has a diode one way and the other the other way in reference to the collector and emitter.
Right now, I am trying to design/build a small power amp circuit to provide a bass speaker to another stereo amp chip circuit (based on the TDA1517). The goal is to build a very simple, 2.1 speaker system so that I can understand all the different components and how they go together.
The diode allows the flow one way, so there are two going in opposite directions. Is this to create a stereo circuit? Or is this something else, like more power. I do not understand what the two different diodes are doing together in the circuit (inside the chips, in the same circuit, etc). I do not want to copy the circuit I have either. I want to unsolder this and build from scratch. So, if I am creating a single, mono amp for the bass, do I need both transistors? I have more questions about this, but for now this is good.
Thank You!