19-01-2021, 12:02 PM
Don't believe that article!! It just suggests bodges to a fundamental issue with the key switches.
The resistor value used depends upon two main factors:
The different logic families have different logic threshold voltages thus the combination of the keyboard switch resistance and and pull up resistor resistance needs to be compatible. There have been 3 families used 74LS, 74HC and 74HCT and each of them have their own nuances.
Irrespective of this, the most critical factor is the key switch resistance.
The resistor value used depends upon two main factors:
- The keyboard logic family used for the keyboard scanning circuit
- The resistance of the keyswitches
The different logic families have different logic threshold voltages thus the combination of the keyboard switch resistance and and pull up resistor resistance needs to be compatible. There have been 3 families used 74LS, 74HC and 74HCT and each of them have their own nuances.
Irrespective of this, the most critical factor is the key switch resistance.