/diy/ - Do It Yourself

>>1192726
>problem with all HC chips?
No, it's a property you will understand when you compare the input structures of TTL and CMOS. In a nutshell, an open TTL input is HIGH while an open CMOS input is undefined because it is static (capacitive) and can have any state. You never leave a CMOS input open.

The image shows a circuit (part of my Theremin project) that is easy to modify for generating a clock signal. Leave off the driver part (4 components) and change the frequency as you need (f=1/t). You can have one pulse per second or you can have 32.768 kHz (approximately..). With one buffer after the oscillator you can have both with a single HC04. Without the buffer you can have three independent clocks. If you want a reliable clock button you will have to 'debounce' the switch, else you may get an unknown series of pulses each time you push or release the button.