/diy/ - Do It Yourself

>>1299482
You can test the following with your DMM or scope:

bit1 appears on out1 and on pin 8 of the 4081
bit2 appears on out2 and on pins 1 and 9 of the 4081
bit4 appears on out3 and on pins 2 and 12 of the 4081
bit7 appears on out4 and on pin 13 of the 4081

4081 is a quad 2 input AND gate
+12V at pin 14, GND at pin 7

out5 is bit1*bit2
if one bit is 0 out5 is 0
out6 is bit2*bit4
if one bit is 0 out6 is 0
out7 is bit1*bit2*bit4*bit7
if one bit is 0 out7 is 0

A first quick test would be to set all bits to 12V and see if all LEDs come up.

2.1kΩ resistors are not common
the standard value is 2.2kΩ