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Topic: Potentially stupid question about Numitron tubes (Read 1 time) previous topic - next topic

BulletMagnet83

...can I use a MAX7219 to drive 'em? I've been perving on some IV-9's and looking at the voltage/current requirements, it doesn't seem a million miles away from what an LED would need, as long as the current set resistor is chosen properly (I have a lookup table). I really fancy some as a quirky, interesting display to play with, and it'd be really handy if I can drive them with parts I already own.

I have BCD to 7seg logic chips by the dozen too, but the fewer parts I have to use, the better. Also, is there a recommended socket/retainer type people normally use for these things, to save me potentially buying the wrong ones and being stuck with them? I see they have long leads rather than fat "valve" pins on the bottom.

Docedison

The "Numitron" tube was developed by RCA in the 60's or 70's as a low voltage replacement for a "Nixie". It uses 20 volts on the digit anodes (works well @ 12 V.. in my direct experience) has a filament tat must be powered (1.5 - 6 Volts @ 100 - 500mA) depends on the spec for the part. I am not familiar with the Russian IV series however the principles are the same... It would take a great deal of work to interface it with a MAX7219. I used CD4017's as decade counters and drove the digit anodes with 2N3906's from the 1 of 10 outputs of the CD4017. The actual details are somewhat... as I did this thing in my 20's and I am nearly 66 years old now. The point is that there is one wire for each "number/value' and not easily done for a 7 segment decoder/driver like the '7219. Supply voltages are different (the CD series had a max voltage of 18V and Spec'd at 15 Volts, making them a great choice for decade counters... in another similar project I used 7442's (bcd to decimal) and mux'd them, 8 data lines 4 for digit data and 4 for addressing a digit counter/latch. All Most Old School and questionable here except as a beginning to interfacing the IV series of displays
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BulletMagnet83

Thanks for the reply! The seller of the IV9's listed the filament voltage per segment as 3.7V and the current as 17mA, with one pin per segment and a common, so I thought "aha, sounds similar to a large LED 7 segment!" in terms of power requirements at least. I'll do some more research :)

Docedison

No the filament takes 50 ms or so to warm up enough to work, that being said there are several old school CD series devices that will work... it's not about what is more efficient but what YOU think looks good. ULN28-3's or others in that family could be used as drivers @ 50V or less (makes interfacing to a pnp transistor real easy) but they are 8 drivers/package so... a chip/digit decode is not possible as it would take 5 280X's for 4 digits... not technically or code difficult, just a lot of wires. The two projects I mentioned were a frequency counter... good bare to a Mhz and a digital clock, both were a great deal of fun as well as a great education.
Questions... I will answer all I can as quickly as I can. I do not offer specific engineering information.... I sell nothing and my time is valuable to me but I will give all the generalized information that is requested, the point, I guess is that you get what you pay for and ALL is free here... So take what you can use and leave the rest alone.

Doc
--> WA7EMS <--
"The solution of every problem is another problem." -Johann Wolfgang von Goethe
I do answer technical questions PM'd to me with whatever is in my clipboard

Zapro


The "Numitron" tube was developed by RCA in the 60's or 70's as a low voltage replacement for a "Nixie". It uses 20 volts on the digit anodes (works well @ 12 V.. in my direct experience) has a filament tat must be powered (1.5 - 6 Volts @ 100 - 500mA) depends on the spec for the part. I am not familiar with the Russian IV series however the principles are the same... It would take a great deal of work to interface it with a MAX7219. I used CD4017's as decade counters and drove the digit anodes with 2N3906's from the 1 of 10 outputs of the CD4017. The actual details are somewhat... as I did this thing in my 20's and I am nearly 66 years old now. The point is that there is one wire for each "number/value' and not easily done for a 7 segment decoder/driver like the '7219. Supply voltages are different (the CD series had a max voltage of 18V and Spec'd at 15 Volts, making them a great choice for decade counters... in another similar project I used 7442's (bcd to decimal) and mux'd them, 8 data lines 4 for digit data and 4 for addressing a digit counter/latch. All Most Old School and questionable here except as a beginning to interfacing the IV series of displays


I think you mixed up VFD's and Numitrons... Numitrons is just a 7-segment display with incandescent wire as the segments.


// Per

Docedison

I think you are Exactly Right and it is a bad error, A REALLY BAD ERROR. FOR WHICH, I APOLOGIZE.
Numitrons were 7 Seg displays that were bigger (led technology wasn't really far enough advanced to supply large > .3 in high digit, displays).
While Burroughs 'Nixie' could there were issues with driving a device that required 180 volts to ionize. RCA made the Numitron as a large display that just needed about 3 - 5V to operate. There was a single VFD display that used 1 of n type control and multiple displays that used 7 segments and grids for digit or multiplexing control. Forgive my memory for fading a little in 40 years.

Doc
--> WA7EMS <--
"The solution of every problem is another problem." -Johann Wolfgang von Goethe
I do answer technical questions PM'd to me with whatever is in my clipboard

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