Now that we have a basic - hopefully working - board to start from, it's time to improve the original design. The first thing we must deal with is the power circuit: the original one uses a simil-LM7805 linear regulator plus a bizarre 5W resistor which are pretty inefficient and generate a lot of heat inside the poorly-ventilated C16 case. Together they are probably responsible for many of the failures of the CPU, TED and PLA which likely amount to 99% of the failures of all C16s.

Today we can do much better than in 1984, since we have cheap and efficient switching regulators. I like those by Traco, so I chose to use the TSR 2-2450: it has a wide input range (6.5 - 36 VDC, even though we must stick to 9V because the input voltage is fed directly to the tape port) and can provide 2A at +5V while reaching an efficiency of up to 96%. At ~10€ it isn't the cheapest of regulators but it is easily available and even easier to solder. If you're going cheap you can use the 1A model (TSR 1-2450, fits the same footprint), it will probably be enough for most uses (after all that's about what the original circuit can provide) but since we're trying to build the one C16 to rule them all, we don't want to spare a cent on this subject, do we? Oh, by the way Traco is NOT sponsoring this project in any way, lol, I've even been accused of something like that in the past.

For the moment I have replicated the recommended circuit from Traco's Application Notes, but I will change that in the future since I want to use through-hole components only, at least for the first release of the improved board. Now my main goal is to see how much space can be saved, since I will be going to add quite a few new components with the mods I have in mind...