Will this 4069-based CMOS low frequency oscillator schematic work?
If you want an easy triangle square wave generator, your relaxation oscillator or this one to use. For a stable reference add 1 MHz Xtal and for really long time constants (2^14) add a CD4060 timer.

I did a quick and dirty design here using a log Pot with 4way cap selector with good tight wiring practice ;) in my SIM.


Extra bits for misc. reasons.


Good Cap Decoupling is mandatory, Ground plane is desirable. 
Then use twisted pair AWG 30 magnet wire for signal paths. (Poor man's coax)
Using a wideband low input current Op Amp to buffer the inverter input triangle wave out is OPtional  (1/3 to 2/3 Vcc) and the unused Schmitt Inverters ganged for a buffer is a bonus.
You can change the Series R and Pot from 1M and any caps to choose 1 decade, 2 or 3 which is a practical limit. So with 3 Caps I spanned almost > 7 decades.
Choice of CMOS family is critical for max frequency and important for lower output impedance.  74ALCV being the lowest Z at 25 Ohms nom.