More Fun with the CD4093 IC as Schmitt Trigger Oscillator. Any practical difference between circuit version with "Enable" pin and Without?

Indeed. The enable input provides a low-energy way to start and stop the oscillator. so you can connect it to another gate on the same chip, or a similar same chip or to the output from a microcontroller.

If you don't need the enable input it can be connected to the positive supply, or you could build the other circuit.

As a switched oscillator both circuits are functionally similar.

However, the second circuit is not a "preferred " way to use any logic IC (or one used in a semi analog mode) as you are switching the power supply to the whole IC in order to control one section. This means that all other gates in the IC are on or off at the same time as the oscillator, which is rather more "wasteful" than using another gate for gating.

Also, the power supply current for the IC must be provided by the gating signal. In most cases this is not a problem as many logic level outputs have enough power and voltage to drive the IC - but if you were using the oscillator in a way that gave a current draw near the upper allowed limit then some IC pins could not supply it.

If you want to gate an inverter oscillator you can do so using a diode from V_control_in to oscillator IC input. When the diode conducts it swamps the feedback via VR1. If a low current enable line is required such that VR1 is too much of a load, drive another gate section and then use that gate to drive a diode disabler. Using a diode allows you to have a high or low disable line as desired - reverse diode polarity to change control polarity.

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I do like the "Forrest Mims"-style diagrams .