Unfortunately there aren't any original IN-14 sockets. But there are good news: you can easily buy IN-14 to 2,54mm adapter from OSH park. I don't know if there is any existing project like this, but for me it is really short work and I could make gerber files for such PCB*. OSH makes three PCBs in one order, so you'd have to buy exactly 2 sets. PCBs would be dirt cheap - probably about 5$ for all 6 PCBs. So if you won't find them in OSH park database, just e-mail me. I don't have any experience with Raspberry PI, but looking at its price I suggest considering any microcontroller family - in a Nixie Clock project you need mostly I/Os and timekeeping accuracy. Unless you are going for IoT project, RPI is going to be expensive and most of its calculating power won't be ever used. There are possibilites to extend I/Os by I2C bus, for example with MCP23008 (http://embedded-lab.com/blog/expanding-the-number-of-io-lines-using-microchip-mcp23008/). You could use four of them, three controlling two 74141 drivers and one controlling 6x optoisolators (TLP627)**. This way you would be able to do ALL nixie controlling via I2c, but it would require many chips, fortunately all avaible in DIP packages. I have never personally used any I/O expander, so all what I wrote is a concept, not a tested idea. If all of your sensors and RTC module (if you are planning to use 4 tubes as a clock, too) use I2C, then you could end up with a project using only those I/Os of your RPI :) I personally prefer using as many I/Os as I can. If you want RGB lightning, I'm sure there are I2C chips capable of controlling them by current sinking. To change brightness of nixies you should "PWM" them. This is the best method of dimming nixies - changing HV supply voltage will eventually lead to undercurrenting tubes, and in that state they do not light a full digit. It is easiest to apply when multiplexing the display, as you need some dead time to avoid ghosting - so to change brightness you just make the dead time longer. For a power supply I would recommend some dual voltage wall wart - 3A for RPI + 12,5mA x6 for 74141s + other modules... you will quickly require high current on 5V line, and to get HV from a switching supply, you will require at least 9V (12V preferably). If you won't find a 5V4A + 12V1A wall wart, then you probably have to either get a transformer and wire it to your liking or make a two-stage boost converter to make 180V out of 5V***. I recommend making a HV PSU basing on NE555 with 12V supply - I made my unit for nixie testing and it was tested for 200V 40mA, reaching 83% efficiency (could be better if I used bigger resistors for feedback).
*in fact, I already made such adapter a week ago as a part of bigger board, which had some unused space, but I deleted it and made a LC-531 adapter, because I lost an auction for IN-14s. **all my 74141 which I tested didn't allow to turn a nixie off by sending a value bigger than 9 to it, there was a slight glow around all digits. So to be 100% sure that a nixie is turned off, you might use either a transistor anode switch or use a transoptor (optoisolator). ***there are possiblities to get 200V out of 5V, but they aren't easy or they provide little current - first one is a switching PSU with a pulse transformer, the other one is making a boost converter to ~60V and use a series of voltage doublers. I find the second one a viable choice only if you want to make a multiplexed clock powered from USB. -- 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/msgid/neonixie-l/25ea6906-8fe7-49b9-9889-a37be0a62d32%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
