> John, if it helps, the circuit attached is stable, to about 2%, over the 
> Vcc
> range of the IC, say 3V to 15V.

FWIW ...HC... CMOS parts are rated down to a 2 Volt Vdd which makes them 
useful for use with as few as 2 cells (Alkaline, NiCd, NimH, ...)

Note that the circuit that Joe showed is not unconditionally unstable - it 
has a stable-off mode where if it doesn't start it won't run. This seldom 
happens in practice, but if you really really care there is a well known 3 
gate version that always starts.


        Russell 

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