so right now, i'm powering my SID with two 9v batteries, and the core is running on a 9V PSU. since i can't find any solutions for a PSU at the moment (no money either), i want to build a small circut to power both SID and Core with my 2x9v set up. if it wasn't running at 18v, i would just make some connections to split the supply line straight to the SID and core, but i'm worried about the heat coming from the core regulator. in order to help with this, i'm thinking that building a mini-psu type thing for the 18v to go into, then straight out to the SID, but between the batteries and the core would be a 9v regulator. would this work and be a good idea?