I promise I won't do a 180 after posting... I still feel like a dunce for posting that other thread (and I'm not done sitting in the corner yet either).
Anyway, I've got two questions that have been rattling around in the vast cavern of my mind a while. Proper answers to both will permit me to finish out the power supply for my project (I have decided for simplicity's sake to use SMPS modules rather than a conventional transformer / bridge rectifiers etc.). I'm usually good at doing web searches for what I need, but...
First question - what is the proper formula for determining the rectified DC equivalent of an AC voltage? I have one section where the DC voltage is simply represented as TXVCC. Poking around in some collected notes, I find that the transformer originally used with this circuit has a separate winding for the TXVCC supply, and which is given as 35VAC, 250mA. I keep coming up with 12 volts for some reason, which is illogical in this case, as part of the circuit is already fed from the 12V bus.
Second question - proper circuit grounding. Do I run the DC ground to earth ground, or do I need to keep it isolated from the AC side, or ? I have seen a capacitor (picofarad capacitance with a voltage of 1kV or higher) used between the circuit and case grounds on SMPS units or similar in the past. Since I have mains voltage on the power supply board, I want to be sure the grounding is done right!
Anyway, I've got two questions that have been rattling around in the vast cavern of my mind a while. Proper answers to both will permit me to finish out the power supply for my project (I have decided for simplicity's sake to use SMPS modules rather than a conventional transformer / bridge rectifiers etc.). I'm usually good at doing web searches for what I need, but...
First question - what is the proper formula for determining the rectified DC equivalent of an AC voltage? I have one section where the DC voltage is simply represented as TXVCC. Poking around in some collected notes, I find that the transformer originally used with this circuit has a separate winding for the TXVCC supply, and which is given as 35VAC, 250mA. I keep coming up with 12 volts for some reason, which is illogical in this case, as part of the circuit is already fed from the 12V bus.
Second question - proper circuit grounding. Do I run the DC ground to earth ground, or do I need to keep it isolated from the AC side, or ? I have seen a capacitor (picofarad capacitance with a voltage of 1kV or higher) used between the circuit and case grounds on SMPS units or similar in the past. Since I have mains voltage on the power supply board, I want to be sure the grounding is done right!