Spencer,
there are a couple of (actually many) options. I have another clock that also multiplexes 60 LEDS as well as 6 7-segment displays in a 1-6 MUX. I control the multiplexing of the tubes by interrupts at about 300Hz, which ensures better timing. The power supply is probably more tolerant to a couple of missed or late cycles without any visual effects. Shift registers are also great tools for multiplexing, especially when used in conjunction with a BCD to 7 segment decoder. That way you can completely control 6 tubes with only one 8-bit port. I would suggest if you do feel inclined to add a small MCU to help out, dedicated it to the power supply, and keep all the clock functions as well as the multiplexing in the main MCU. So many options..... :-) Bill v. Dijk From: [email protected] [mailto:[email protected]] On Behalf Of Spencer Sent: Sunday, July 21, 2013 2:07 PM To: [email protected] Subject: Re: [neonixie-l] IV-11 VFD Thanks for the schematic. It would be overkill if it was just for a clock but I want to save cycles on the MCU since it was multiplexing the tubes and boosting the voltage. I was taking cycles away from the MCU and it was causing flickering. I looked at either a PT6311 or having a dedicated attiny to run the multiplex/booting and feeding via serial the tube display. So it just looks like the filament voltage is biased (is that the current term?) to the grid voltage. So -18v filament one end and -20 the other end and grid/anode is -20v. I am using MC34063 inverted to generate the voltage. I'll give it a shot it and see what happens! _____ From: Bill van Dijk <[email protected]> To: [email protected] Sent: Sunday, July 21, 2013 7:07 AM Subject: RE: [neonixie-l] IV-11 VFD Spencer, Attached is the schematic for my IV17 clock with a PT6311. It is a chip that takes a bit of figuring out, also on the software side. My clock displays time (why not eh?) and the full date in a marquee format as well as ambient temperature. I would suggest the PT6311 is possibly a bit of overkill for a 7 segment based clock design. Bill v. Dijk From: [email protected] [mailto:[email protected]] On Behalf Of Spencer Sent: Saturday, July 20, 2013 2:29 PM To: [email protected] Subject: Re: [neonixie-l] IV-11 VFD Got it working! It lights up now and it looks like I will have to change the filament resistor. I was using a 30 ohm with +5V but ooo boy does it get bright with that. I'll drop it down to around +1.5V and can take it from here. Thanks again. _____ From: John Rehwinkel <[email protected]> To: [email protected] Sent: Saturday, July 20, 2013 12:54 PM Subject: Re: [neonixie-l] IV-11 VFD > Thanks for the reply. I put the -25v on pins 1 and 11 (cathodes) and GND on pin 2(grid) and GND on a random anode to see if it would light up and nothing illuminated. The filament needs to be hot to emit electrons for the VFD to operate - this is normally accomplished by heating it electrically. I did kind of gloss over this -- you have to have voltage across the filament as well - this is true no matter how the other voltages are supplied. The "ideal" method is to have a small center-tapped transformer providing the AC filament voltage (generally something between half a volt to a few volts), and hook the -25V to the center tap. I often use a generic 6.3V filament transformer, with series resistors to drop the voltage to whatever the VFD filament needs. Some people don't want to bother with an AC filament voltage, and just run it with DC - this will work, but can lead to brightness gradients in some tubes. So, just to light something, at a minimum, you'll need -25 volts at one end of the filament, -(25 + filament voltage) at the other end of the filament, and 0V at the grid(s) and anode(s) you want to light. - John -- 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/C81F0687-BB98-4FAD-A200-7450550 41C3E%40mac.com. For more options, visit https://groups.google.com/groups/opt_out. -- 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]. 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