I recently came across a bunch of 4093 chips:
These are Quad NAND gates, with Schmitt trigger inputs. It turns out you can use these to make oscillators and monostables – just like the 555, but more compact with less parts.
So I updated the oscillator application I wrote to calculate out values using this oscillator as well as a 555. It looks like you can get more of usable range with this device.
One thing – the NAND gates cannot source as much current as the 555 timers so you might need to add an opamp as a voltage follower. LM324 does this nicely.
One nice feature of the 555 oscillator is that you can connect another LFO signal to pin 5 and create a vibrato effect for even more ‘musicality’ – something lacking with the NAND gates.