Ok, so something doesn't seem to add up. I tried it with R1= 100k, R2= 10k, R3 = 470k, and C1=22uF. By these calcs I should have a 1.8s charge, a 10.3s discharge. I got an 8Hz flash instead... could it be because the NAND doesn't have a Schmitt input? this is the NAND I'm using in my test: mouser.com/ds/2/149/nc7wz00-305128.pdf

furthermore, what role does R2 play? I was presuming there was some discharge through it, at one point at least....

That's two of us. Which is why I posted...

let me throw a cog in the works - these are 5V parts, and the VIH level is 3.5V, and the VOL level is 1.6V. How does that change the equation? Or do I need the exponential function for this?

Besides, it's locked. I can't uncheck it if I wanted to. Let's see what pops up.

if I only had the time... lol

@Doodle it does not have them but the circuit works. Just not sure how to tune it.