74xx TTL devices have a rather high input-low current, on the order of 1mA, so you should use a much smaller pulldown resistor, say 100 ohms, or perhaps none at all. Logically, it should not be possible for more than 1 output to get driven low on the 7441, but that only applies if all parameters in the datasheet are met. I suspect that the 100K pulldown isn't really pulling-down to a logic-zero, and the IC has gone to some intermediate logic state which is non-deterministic.
For the LEDs, I would recommend having a 2K series resistor and driving from +12 VDC. That works out to around 5mA of current which is enough to make many LEDs visibly glow and well-below the 7mA max current rating of the 7441. On Tuesday, September 26, 2023 at 6:30:15 AM UTC-7 Craig Garnett wrote: > I bought a 74141 on Ebay and I had a bit of trouble with the delivery but > it arrived eventually so I'm trying to test it on the breadboard. > > I've hooked up LEDs from +ve to all the outputs and pulled the 4 address > lines down to ground with 100k > > When I power it up 6 of the LEDS are on and raising any of the address > lines does nothing. > > It doesn't look good does it? > > Craig > -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from this group and stop receiving emails from it, send an email to neonixie-l+unsubscr...@googlegroups.com. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/f0359bfc-0247-4234-b2d4-bde4bee06d54n%40googlegroups.com.
