A key way I try to solve problems in general is to see where and how they can be simplified (I guess that must be a leftover from highschool math classes). After all, the fewer moving parts, the less that can go wrong. On top of that, if you keep building on a smaller thing that works and test it incrementally, you can tell when things start going wrong, which leads to a much narrower problem to solve. In the case of the HV programmer, that firstly meant to remove the secondary header. I only need to reprogram a 14-pin IC right now in any case, and I’d much rather have a working HV programmer for that, than a general one for a future use case that I don’t know about yet.
A quick retooling in KiCad leads me to the following schematic:
Now, ideally, if I wanted to be very specific about how I make schematics, I would much rather have the master IC to the left of the target IC, so that my input pins are always on the left and the output pins are always on the right. Ideally, I want power to run from top to bottom in a schematic, and the signal to run left to right. It just makes things easier to read for me. However, this is supposed to be a quick tool that helps me do another thing that I’d like to do, so I’m not going to polish this up too much. I’ll work on KiCad library management some other day.
Fortunately, the simplified schematic leads to a far simpler perfboard design with fewer connections:
As you can see, I still chose to keep a lot of solder lines in there rather than jumper wires. For one, I think that’s something of a guideline to begin with, but secondly I also just want to learn how to do that properly. The only way to learn is to keep on trying, so I may as well start here. This time, though, I think I may want to try out soldering the lines first and only adding the components later. That’ll allow me to mess up more and throw the board away if I really ruin it. The most I can lose is some perfboard and solder, at that point.