Simple battery powered application uses the classic "gated oscillator" described in app note for CD4093.
One would expect the Control input of the Schmitt trigger NAND to simply turn the oscillator on or off. Using the Texas Instruments CD4093BE from Digi Key yields unexpectedly a voltage-controlled oscillator where the Control pin voltage tunes the oscillator over a 20:1 range.
Heres what ACTUALLY happens:
X-axis is Control pin voltage in volts, Y-axis is oscillator frequency in Hz. Vcc is well bypassed, regulated at 4.95 v. There is no sign whatsoever of Schmitt trigger action as the Control input is varied across the threshold of oscillation. Oscillator uses C = 0.01 uF and R = 100 k fixed resistor which was supposed to be a thermistor until this problem cropped up.
(Q) did we get a bad batch of Texas Instruments CD4093BE from Digi Key ?
(Q) if the CD4093BE by design does not behave as expected, then what does ?
