Hi Allen, Welcome aboard! Nixies are very enjoyable things to work with.
First off, you need to have a current-limiting resistor in series with your 170 volts!!! 15k is a good nominal value to start with. Most nixies of that size need to have their current limited to around 2 or 3 milliamperes. A real nice old book to have that explains the 74141 driver ic is Don Lancaster's "TTL Cookbook". You can find a copy from most used booksellers for fairly cheap. Basically you can rough out the nixie current by taking the power supply voltage minus the strike voltage and dividing that by the resistance value. In this general case those numbers would be 170 minus 150 which is 20 and then divide that my 15,000. That comes to .0013 or 1.3 milliamps. If you'd use 10K then those numbers would be 170-150=20 then 20/10k =.002 or 2 milliamps. All nixies have a data sheet that shows the recommended power supply voltage, the average strike voltage, and the recommended current, and the recommended series resistance. But you MUST have the series resistance otherwise you will overdrive the nixie and ruin it very very fast! The driver ics such as 74141 use a 5 volt supply and have 4 binary inputs. They have 10 single outputs which connect directly to the tube cathodes. The cathodes are the digits. Meanwhile, the tube ANODE goes to the series resistor (15k for starters), and the other side of that resistor goes to the +170 VDC power supply terminal. The 5 volt DC power supply that powers the driver ic is on a COMMON negative ground with the 170 volt supply. What happens is that when the proper binary code is applied the the 1-2-4-8 inputs on the 74141 ic, the appropriate 1-of-10 output gets switched to the common ground, turning on the nixie digit. It will drop to within a few volts of ground. Those 10 outputs on the driver ic are capable of handling about 55 volts and that is enough to make them safe to use on nixie cathodes. Be extra careful never to short any of the 5 volt pins to any of those ten pins that are connected to the nixie cathodes. Any short, however brief, will INSTANTLY destroy this ic. Beware also the 5 volt power input pins on this old ic are pins 5 and 12! Be careful! That is the quick general explanation. More detailed in depth reading can be done by finding the exact tube data sheets and by looking over the 74141 data sheet. There is also 7441, which was an earlier version. And also the rare 74142, which has a decade counter built in. There are Russian equivalents of the 74141 available on ebay. Hope this helps some. Chuck ---- Original Message ---- From: [email protected] To: [email protected] Subject: [neonixie-l] Why driver ICs? Date: Fri, 1 Feb 2013 19:44:37 -0800 (PST) >Another nixie newbie here hoping y'all will show compassion for my >ignorance. > >I have been an amateur electronics hobbyist since childhood, mostly >analog >(primarily audio & RF-related). I've started playing with some >ZM1000s, and >built a simple tester to plug them in & cycle manually through all >the >digits (image at www.lutins.org/projects/nixie1.gif). This is a >simple >device, with the positive side of a 170V power supply connected to >the >anode and the negative side switched between digit cathodes. I am not >using >a driver IC, and here is my primary question: What is the main >purpose of a >driver IC? > >If i understand the specifications properly, 170V is an "ignition" >voltage, >after which a 125V "maintaining" voltage can be used. Does a driver >IC have >anything to do with this, or is this another issue entirely? And will >i >shorten the life of my nixie by supplying it continuously with 170V? > >Thanks in advance for helping me merge onto the nixie highway! > >-allen > >-- >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 [email protected]. >To post to this group, send an email to [email protected]. >To view this discussion on the web, visit >https://groups.google.com/d/msg/neonixie-l/-/UgY5daHzjuEJ. >For more options, visit https://groups.google.com/groups/opt_out. > > $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 unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send an email to [email protected]. For more options, visit https://groups.google.com/groups/opt_out.
