74hC959, 12 segment LED, npn 2222
Topic: 74hC959, 12 segment LED, npn 2222
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Working above my skill set
Re: 74hC959, 12 segment LED, npn 2222
Jan 21, 2021, 02:16 pm
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.