This circuit was obtained from an 80's Electronic Engineering. The circuit detects ice formation by triggering a warning light. The operational amplifier is of the time.
A configuration like the one used with the 4013 is also suitable for the 4027. The amount of time...
Mouser Electronics is already providing new MOSFETs EF SIHx28N60EF of Vishay series for voltages...
The 4046 consists in a PLL with na internal oscillator controlled by voltage (VCO). Figure bellow...