16 possible characters displayed from 4 24 vdc PLC outputs
1 = A
2 = B
3 = A+B
4 = C
5 = A+C
6 = B+C
7 = A+B+C
8 = D
9 = A+D
0 = Mystery Pin(s)
A = B+D
B = A+B+D
C = C+D
D = A+C+D
E = B+C+D
F = A+B+C+D
MISSING: Current limit resistors between chips ? Why does 0 light up ? How to reduce the 24 volt signal to 2 volts ?
How to wire ...
www.electronics-tutorials.ws/combination/comb_6.html
Decoder # 74LS48 for common-cathode (-)LED types
