Ok. I just finished some tests, and it seems to work perfectly.
Here is the schematic I refer to:
(I forgot to add values, R2 and R1 are both 1k ohm
Q is the output, that's what I hook to my scope.
C_HI is the high end of the cap (if you want to test a polarized cap)
C_LO is the low end. --these don't matter on standard ceramic caps
Vcc should be between 5-9v, but can be up to 15v safely. 5v is a good TTL level.
To find out C, use the equation C=t/R (from t=RC)
Since my scope only gives frequency, I substitute t=1/freq
We know R (R=r1+r2), so we get
In my test case, I get freq=2.25676kHz
that means that freq=2256.76Hz
The Cap I used was labeled 224J, which makes it a .22uF +/-10%