Hi Steve, TTL inputs tend to float high when left unconnected. Therefore, when the 74141 inputs are left floating, you are encoding 1111 (hex F) on to them.
74141 blanks the tube for all inputs greater than 9 (1001). To encode a zero, try taking all four inputs to a solid "low" condition. Chuck > > >---- Original Message ---- >From: [email protected] >To: [email protected] >Subject: RE: [neonixie-l] Minimalist 74141 Operation >Date: Wed, 20 Oct 2010 19:13:46 -0700 (PDT) > >>Hello all, >> >>I'm trying to get a 74141 (the russian versions) to operate on my >>breadbord in the simplest manner possible, and I'm obviously pretty >>stupid. >> >>This is my circuit: >> >>http://goo.gl/P8uU >> >>I have a purchased high voltage and 5V power supplies that are >powered >>from a 12 V wall wart. >> >>I powered my 74141 with 5V from the 5V supply (onto pin 5), and the >>anode of my nixie with the 180V supply. I then hooked one cathode of >>the nixie onto pin 16 of the 74141, which is the 0 digit pin. I >>grounded pin 12 to the ground of the 12 V wall wart. >> >>My reasoning is that with no power to the BCD inputs that I am in >>effect encoding zero, so the zero pin should be sinking current. >> >>And, nothing! >> >>If I ground the nixie directly it lights and my 5V supply is >>outputting 5V as measured by my multimeter. I've tried four >different >>74141's, all the same. >> >>What am I doing wrong? >> >>Ground is ground right? Are all grounds considered equal? I notice >>both my power supplies have separate ground pins coming out of them >>over and above the ground pin for the power going in. Why wouldn't >>these just be wired together on the power supply's circuit board? >Why >>do they supply another ground pin? >> >>The 74141 data sheet is: http://goo.gl/JCN9 >> >>Your opinions and assistance are very much appreciated. >> >>Thanks in advance. >> >>Steve >> >>-- >>You received this message because you are subscribed to the Google >Groups "neonixie-l" group. >>To post to this group, send an email to [email protected]. >>To unsubscribe from this group, send email to >[email protected]. >>For more options, visit this group at http://groups.google.com/group >/neonixie-l?hl=en-GB. >> >> $4.95/mo. National Dialup, Anti-Spam, Anti-Virus, 5mb personal web space. 5x faster dialup for only $9.95/mo. No contracts, No fees, No Kidding! See http://www.All2Easy.net for more details! -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To post to this group, send an email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
