So I decided to build power supply unit for my modular synthesizers. 2-in-1 Design: +/-15V (3A each) and +5 (1A) for TTL logic ICs modules. I started from enclosure, learning the SolidWorks in the same time. So after the box was finished I started to look the easiest and rugged solution for 7A PSU. Sure it is linear design I had to choose from. So for the TTL Ics, where 1A is enough I chose classic 7805 regulator with crowbar over-voltage protection. And for the +/-15 3A rails LM723 with current booster. Later I decided to add EMI-filter and soft start (tactile button and surge protection in one circuit). Soft start will use 7812 regulator and two 24V relays powered from 250mA stand-alone power transformer. This work took 3 month, and before go to production stage I wanted to check everything once again and ask an advice on this particular implementation. First requirement is protection, and safety, coz this PSU will supply 12k setup of modules. The second one is not to be overkilled. Also I'm interested in ways to reduce impedance if there is a common practice to do it, avoiding the complex procedures of measurement the unit under load. And it could be possible that I have made a mistakes, as fatal and minor ( I suspect that could make mistakes in the diode bridges) so kindly ask you to help me eliminate them. And the last thing is transformer, still can not calculate required VA and voltage of secondary.
And +/-15V based on LM723 Here are specific questions about this: 1. What is the best caps to use for c4 and c6 at the voltage outputs? 2. Is it possible and is advisable to replace the BD911 with TIP147 and BD912 with TIP142 (I have them lot)? If yes, then how? 3. What is the purpose of 470uF c3 and c7 before output?