I am using the Olimex PIC-MAXI-WEB board for a project and I got myself stumped. The input is "9-25V DC or 7-18V AC range, the bridge rectifier on the input allows both AC and DC adapters usage and makes power supply polarity problems go away."
The schematic can be seen here: https://www.olimex.com/Products/PIC/Development/PIC-MAXI-WEB/resources/PIC-MAXI-WEB_sch.pdf
But that rectifier is causing me some sleepless nights. I am only using DC (12V in my case), but I need to sample the ADC from a system running off of a different power supply (meaning I will want to tie my grounds together to keep everyone on the same potential). In an ideal world, I would tie the two power supply grounds together at the power supplies and then everything is happy, but it seems to be that the 12V's ground is not going to be the ground the uC sees on the board since it has to go through the rectifier. Short of modifying the board so that I tie the board's ground to the power supply ground (and not have it go through the rectifier), is there any way around this?
The schematic can be seen here: https://www.olimex.com/Products/PIC/Development/PIC-MAXI-WEB/resources/PIC-MAXI-WEB_sch.pdf
But that rectifier is causing me some sleepless nights. I am only using DC (12V in my case), but I need to sample the ADC from a system running off of a different power supply (meaning I will want to tie my grounds together to keep everyone on the same potential). In an ideal world, I would tie the two power supply grounds together at the power supplies and then everything is happy, but it seems to be that the 12V's ground is not going to be the ground the uC sees on the board since it has to go through the rectifier. Short of modifying the board so that I tie the board's ground to the power supply ground (and not have it go through the rectifier), is there any way around this?