Here's a simple to build decoder board for anyone wishing to connect up and use one of the widely available inexpensive 4x4 matrix keyboards. The circuit is easily adaptable and uses just 5 easy to obtain logic ICs.
************** PLEASE NOTE that I made an ERROR in the circuit diagram given in the video. The connection from the four diodes goes directly to input pins 13 and 12 of the 132 NAND gate package. The 1M resistor and 47n capacitor go between this connection and ground. Sorry about that! *************
Just had a query about the oscillator driving pin 2 of the 161. The resistor is 1M Ohms with a 1nF capacitor and the approximate frequency is 1.7KHz. The actual running frequency is not that important!
