I made a psu using a center tape transformer. It has two output circuits for different voltages. One input of both the circuits is a common end of the transformer, similar to the schematic attached (just to show the connection). I want to supply both the voltage to different part of one project. (like 5v to the MCU and 12v to operational part, motor etc.). To make this happen there should be one common ground (or negative). But I found big voltage between negatives’ of the circuits (rectified negative of 5v and rectified negative of 12v). As both has a common input wire from the transformer, and I will have a common ground.
- Why both negatives’ are of different level (voltage)?
- What should I do to get a common ground?
- Why in the graph one output(dc2) is stable and the other (dc1) is not (dc3 is negative of dc1)?