Go Down

Topic: 74hC959, 12 segment LED, npn 2222 (Read 215 times) previous topic - next topic


Sorry I used the wrong PN.
The problem seems to be a decoupling capacitor and one stray 220k resister on the transistor base. Got a 220k mixed in with the 220ohm. Still need to verify this was the problem but it's working on a bread board again and that's the only difference I can see.  Waiting for some ceramic caps to arrive in the mail. But when not lighting all the leds I see some artifacts on the led bar namely dull lighted sections.  My only other concern is cross talk between wires but I am really not sure if this is possible on a 5v application.  I ended up using a volt meter on every leg of the run and questing anything below 4v.

Go Up