Surely, with enough electronics knowledge it should be possible to build a new Amiga hard drive controller and interface, as well as monitors which are compatible with classic Amigas without using a scandoubler or flicker fixer. Please will someone tell me what problems there would be doing either or these things?
Yes, with enough knowledge, time and money you can do practically anything. The problem with the sorts of projects you mention, the knowledge required to do the job properly doesn't come overnight. As others have mentioned, to design a drive controller from scratch, you need to have a thorough understanding of the interface to the Amiga and to the drive in order to both design the controller hardware plus the software on the Amiga side. Then you need to look at physical construction, mounting, etc.
I've been electronics engineering for nearly 20 years and find it frequently annoying when people view any complex piece of electronics as something that can be whipped up by anyone holding a qualification to operate a light switch in five minutes by getting a few ICs and making a few random connections between them. Every good design is generally the result of years of experience and hundreds if not thousands of hours of development and testing.
I tend to favour older technology in new designs because it's often easier to work with and requires less design work as you can re-use proven circuit blocks from previous designs. e.g. 'modern' high speed logic can require complex design around signal propagation times, rise/fall times, PCB track lengths and more.
As an example, here's a
design report from single board 8-bit embedded computer I designed from scratch a few years ago as an in-house universal production testing solution. Many of the individual blocks were copied from previous projects and designs with the intention of reducing development time and cost as much as possible. As a result the entire thing worked first time and met budget. But it still took weeks of hand made prototype blocks, calculations, writing hardware interface software and a basic operating system. See page 53 for how long it practically took and cost, and this is just a simple 8-bit embedded system reminiscent of what you'd see in the 1980s.
