Part 2. In this post we explore using the Quad NAND CMOS chip as an oscillator. This is actually a pretty simple circuit. We use the aforementioned CD4093 chip. All we need to add is a capacitor and a matching resistor to generate a square wave Lunetta style.
In the previous post in this series, we looked at the Quad NAND CMOS chip and how the NAND logic operation works. We can utilize this behavior to create a square wave oscillator. The animation below shows how to construct the circuit.
NAND logic oscillator on the breadboard
Let’s hook up a CD4093 chip to a 9V DC power supply.
Connect the 9V power rail to pin 14 Vcc of the CD4093 chip.
Connect pin 7 Vee of the CD4093 chip to ground.
Let’s create an oscillator to the first NAND gate. Connect pin 1 (input 1A) to the 9V power rail so that pin 1 is always HIGH.
Insert a 100k resistor between pin 3 (output 1Y) and pin 2 (input 1B).
Insert a 100nF capacitor between pin 2 (input 1B) and ground.
Let’s hook up the oscilloscope by probing the output 1Y and connecting the ground connector to the circuit ground.
And there you have the expected square wave output.
Cool but still not that fancy. There are lots of logic chips you can use to get the same result. The reason why we use the Quad NAND will become apparent in the next post in the series where we modulate one NAND gate with another.