Thanks for the heads up on that zener diode approach. Note taken, use an IC for that as well.
After many searches I found the
*LT1074* to be the best IC for all the voltages I need. it can be configured in both buck and inverting topologies, and the good thing is the inverting topology still allows for high current as opposed to many other ICs that could only go up to 900 mA. On page 13 you can find the typical application circuits, and in the pages before there is how to calculate the values for the components.
Next there are the questions of things still unclear to me. I apologize for the numberless questions and for any dumb question.
1) there is an optional filter in the positive-to-negative inverter which uses a 5uH inductor: is that a copper wire inductor or a high-frequency resistor-like component?
2) same question as before for L2 in the buck converter circuit. Also, is the L2-C4 circuit performing the same purpose as the optional filter purposed in the positive-to-negative converter?
3) can you please show me some example filter schematics for connecting in parallel these circuits? if you can include some "general purpose" values for the components it would be great
4) which switching frequency would you recommend using? Could you describe the pros and cons for using low or high switching frequencies? I suppose a high frequency will create more noise, is that correct?
5) PCB layout: is it OK if put all the ICs on the same PCB or should I put each circuit on a separate PCB? Would separating them help reduce any noise?
6) still about PCB: would it help reducing noises on the outside if I'd use a copper or aluminum housing around the PCB (like the ones used on WiFi cards), connected to GND? Maybe with a series resistor? I'm asking this question because the power supply distance from the breadboards is going to be quite small and I fear it would create interferences in the breadboarded circuit and in the power supply as well.
7) D1 is reported to be the
*Motorola MBR745* 7.5A Schottky diode. Does it have to be this particular one for any reason or another 7.5A Schottky diode will do well?
Thank you for all your patience if you're willing to answer all those questions