OBG VCF TLA OMG (part 3)

The VCF front panels from JLCPCB, my first PCB front panel order, arrived last week:

What looks like white streaking in the black areas really is light reflecting off the not entirely smooth texture of the surface. It looks better in person. Not the highest quality panel ever made by any stretch of the imagination, but on the other hand it’s nicer than the panels I’ve attempted to make myself, plenty good enough for me.

I soldered up the VCF. It didn’t work. I took some time off, then tonight went back and debugged. There are two transistors with very tight footprints and apparently there was a solder bridge; I removed them, soldered in two new ones, still had a short. Visually I could have sworn they were not connected, but the multimeter said otherwise. Removed those, soldered in yet another two new ones, and it’s working:

Sort of. I mean, it works, but it turns out four of the five pots are connected backward, so increase counterclockwise. I guess that’s an advantage to wired versus board mounted panel components. Wires I could switch around, but PCB traces, not so much. I can only switch them around in software, and then order new boards. Which is what I did. Only the panel board, of course; the main circuit board is okay. This time I sprung for somewhat faster shipping, because who knows what state postal delivery will be in three weeks from now. I’m also getting some Breadboard Friends.

Another deficiency, if you want to regard it as such, is that it doesn’t go into self oscillation. Wilson said it would, barely, but it doesn’t. I like filter self oscillation so I might see if lowering a resistor value makes it happen.

Also there are no 0.1µF bypass capacitors here because of an error in my last Tayda order. Next Tayda order should arrive Thursday and I can add them in then.

Meanwhile the original, now unwanted PCBs from JLCPCB still haven’t arrived, and appear to have gone on a sightseeing tour:

But allegedly they’ll be delivered tomorrow.

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