Steve, you will find vociferous supporters of both multiplexed and non- multiplexed designs! I have built a number of BOTH, so will summarise my view:
>Multiplexed often means less or simpler hardware (the same driver electronics >serving more than one tube). >You can often use smaller PIC chips (needs fewer pins if multiplexed) >But Multiplexed also then means more complex software! (if using a PIC >processor or similar) >Probably not worth the EXTRA electronics of a hardware multiplexed design >Multiplexing means you can also more easily introduce effects such as display >dimming and even fading >You need to scan the whole display at least 70 times per second, to avoid >flicker. Talk of several hundred times a second leaves me baffled. Why bother? >Some nixie tubes will "sing" gently under multiplexed drive. You can "tune >out" some of this by careful selection of your multiplex rate >For the same average current, I judge direct-driven displays to be slightly >brighter >In six-tube clocks, you will see 2x, 3x and 6x multiplexed design where three, >two or one nixie tube(s) (respectively) are driven at any one time. >Personally, I think the 6x design is asking a bit much of the nixie tube - to >get reasonable brightness, you have to hit it with pretty high peak currents. >I have no opinion on the relative life expectancy of the nixie tubes, >Multiplex Vs Direct driven, provided the manufacturer's spec is adhered to. >Ask me in another ten years, and I'll reaffirm or update that view! Looking at the circuit you reference - a 4x (one of four design) is fairly standard BUT - What's that '555 doing in there? REDUNDANT HARDWARE! Get your processor PWM to drive a FET with some voltage feedback, to create the HT. Use the capabilities of your processor to the full, to minimise the hardware, for a more elegant solution - always. Given your starting processor (I am not too familiar with the Aduino range), you could probably skip the '595 shift registers and drive the '141 BCD decoders directly from the processor, if going down the multiplex route. Why not breadboard BOTH and see what you think? On Oct 17, 1:06 am, Steve <[email protected]> wrote: > Dear group, > > I'm very new to electronics and designing my first clock circuit now > (four digits) which is composed around an Arduino driving two shift > registers (74HC595) which are driving four 74141's that drive the > nixies. I basically copied the designs available on ogilumen.com if > you are at all familiar with them. It works nicely on my breadbord. > > From reading these groups I've stumbled upon this multiplexed design: > > http://i46.tinypic.com/2saghhe.jpg > > I don't need to do any of the fancy stuff with the special clock chip, > but what I am wondering is why a multiplexed design should NOT be my > first starting point? > > I can get rid of the shift registers completely, cut down to only one > Arduino driven 74141 and all I need to substitute are anode > transistors again triggered by the Arduino. > > I would love to hear the advice of the group. > > The tubes I am using are IN-8's where have "pulsed" specifications, so > I'm assuming they are designed to be multiplexed. > > Thank you in advance. It is very much appreciated. > > Steve > > P.S. The original multiplex post > was:http://groups.google.com/group/neonixie-l/browse_thread/thread/32dad1... -- 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.
