What's inside the non-Bluetooth Powered Up Hub (85825)?
In particular, what sort of electronic components are present?
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We can begin to explore this part by carefully removing the top cover to reveal the PCB:
On the left, we can see a current-limiting thermistor (MF-MSMF075). On the right, we have a pair of Powered Up connectors. In between the connectors, there is a surface mount LED labelled D1 that is used as a power indicator.
Let's remove the PCB:
Under the PCB, there are a couple of metal springs. These provide the physical resistance and locking capabilities for the switch but perform no electrical function.
That's the main housing without the springs present.
Let's look at the bottom of the PCB:
This clearly shows how the electrical side of the switches are implemented. The two components on the right are usually in contact with the board and are allowed to slide to make or break contact with the contacts shown on the board. A quick examination of the traces shows that the contacts are used as DPDT switches that are wired as crossovers to allow polarity reversal.
Overall, this is a very basic basic battery box much like those for older systems such as Power Functions, with the exception that this box allows two motors to be controlled independently.