These are designs that I have worked on in the past and have completed enough to work, but that I don't consider good enough to post as projects. This might be because they have problems, or they don't work well for what they're supposed to do, or they're just not that useful. Also, I don't plan to work on the projects on this page anytime soon, so feel free to borrow ideas.
Active 3-band EQ
This design is a sort of offshoot of the Mid Boost/Cut. I played around with it in LTSpice to see if I could get more control, and I managed to get a 3-Band EQ working. The problems are that it requires specific and hard-to-get pots, and that it's untested.
This circuit is an expander and a distortion that only works on bass. It's a neat design and it's one of the most complete and bug-free circuits on this page. The problem is that it's really not that useful. I suppose some people might like it but I don't find it useful at all. It's really more of a proof of concept for using diodes' resistance drop as an expander.
This was my attempt to cram as many different effects as possible into a 4049 and a LED-LDR. It works well enough, and with surprisingly little LFO tick, but there are quite a few issues with levels (you need to tweak the volume a lot) and all of the effects are pretty mediocre.
This is a simple mid scoop circuit. It works well, the only problem is that 500m inductors are usually pricey and unwieldy.
This is one of the first circuits I designed, and it's pretty problematic. The LFO wave is chopped on one end, and there are ticking issues with some amps.