I had an super extra very extraordinarily rough day, and week too, trust me on that one.
"only an 8 pin chip"? It will be a lot less DIY versatile when the largest physical size can fit 50 on a grain of rice!
Part of my point was the least expensive MC34063 was $0.61. A stamp is $0.44. That is $1.05.
Can have it dropped in my mail box in 4 weeks for $0.99, and ready to use.
Part of my point relates to "Swap it out for a 50V and be done with it." Why bother?
Most of my point was Treehouse is looking for less than 500ma output, 24V to a stable 5V, without linear 78XXs, and anybody, almost anywhere in the world, can get one ready to use for $0.99. And it probably works better than a DIY unit.
Many of 'us' could build a 78xx or 555 or 741 from parts. That doesn't make it a great idea to persue that option in the interest of the pure resulting function, right?
That's all I intended to imply.
G-