Vintage Curvy PCB Traces with KiCad 7

RE: Vintage Curvy PCB Traces with KiCad 7

shabaz — Sat, 08 Jul 2023 18:08:01 GMT

This is an old Sony AM radio I'm repairing (the electronics is faultless, still working fine after all the decades). I think this board must have been completely hand-soldered. This is late 1960's. They used the single PCB as a chassis for everything, all parts well-positioned to squeeze in:

I'm always impressed how compact they managed to make things. Here's a photo of the top side since it's interesting:

At least one of the transistors (I cannot read the part markings easily for all of them) is labelled Sony C870, i.e. 2SC870, and manufactured by Sony too.

Incidentally, not all of the transistors might be silicon; two of the metal cans visible on the right side, are not capacitors, they are transistors, used for driving the output speaker transformer. I cannot read the print on them, but they may be 2SD65, i.e. germanium NPN, according to a schematic (but Sony may have changed them, since I couldn't find C870 on the schematic either).

It's interesting seeing how they worked around the problem of not having NPN and PNP transistors, by using the transformer coupling.

RE: Vintage Curvy PCB Traces with KiCad 7

jc2048 — Sat, 08 Jul 2023 13:47:07 GMT

This one possibly dates to the 1950s. The board came to me as part of a 'bargain bundle' of surplus boards in the early 1970s, but must have been made at least a decade before that (I can't imagine IBM would have still been building logic with discrete transistors very far into the 1960s). It's single-sided. Not fibreglass, so would it be phenolic-paper?

Construction is interesting - it appears that the leads were cropped and folded over before flow-soldering. Another interesting feature is using ridges from the board-stamping on the top surface to space the transistors to reduce stress on the legs.

RE: Vintage Curvy PCB Traces with KiCad 7

jc2048 — Thu, 06 Jul 2023 13:20:38 GMT

This is a double-sided board I did in the early 1980s. This was a home project. It's done using tape-and-dot, with transfers for the chip footprints, all done twice life-size and reduced with a process camera. The board isn't pth (too expensive at the time), so the vias are breakoff pins. It's a memory board, so it made sense to run the tracks through the pins along the row of eight chips. The style is an odd mixture of wavy lines, and the 45-degree angles which was the 'house style' where I worked and which I defaulted to out of habit.

RE: Vintage Curvy PCB Traces with KiCad 7

Jan Cumps — Tue, 04 Jul 2023 19:14:46 GMT

"They were done manually by rolling out UV-light-blocking crepe sticky-backed tape onto clear film."

That was my first electronic summer job. Designing double-sided drivers and voltage doublers to create high voltage generators.

These circuits were used in a powder paint factory, where they'd paint alu and metal profiles. By applying high voltage to the profiles, the paint powder would be attracted to those profiles, and the yield was way higher. More powder reached the profile faster, and stuck better before going into the oven.

RE: Vintage Curvy PCB Traces with KiCad 7

genebren — Tue, 04 Jul 2023 04:32:32 GMT

That is pretty cool. I used to design PCB using rolled tape and dry transfer rub on pads on clear Mylar. I have probably have done 40+ boards using this method. The style really does bring memories!

RE: Vintage Curvy PCB Traces with KiCad 7

ggabe — Tue, 04 Jul 2023 01:39:44 GMT

I love this plugin! Here is an example I've just received. Next, I'll try the teardrop, if I have a board dominantly through-hole.