Seven digit Nixie project

[Mitch]

Hi All,

I'm using 7, 2N3904 transistors with the collectors to VCC, emitters to each LED anode, and bases to seven microcontroller outputs, through a resistor. Is there a chip available with a similar function, to reduce the parts count?

Thanks in advance.

[threeneurons]

As long as you're using a microcontroller like the PIC or AVR, and not an 8051 variant, why not use charlieplexing ?

Look at page 4 in this document:
http://nixietube.info/NixieTransistors.pdf

In your code, you twiddle both the port and its DDR bits. It can turn only one output ON at any time. Each output uses two I/O lines, but they are shared in a matrix. To turn on an output, you set the DDR bits corresponding to its base and emitter as outputs. You send a 1 to the base port bit, and a 0 to the emitter bit.

You can run LEDs directly, by hooking the anode in place of the xstr base, and cathodein place of the emitter. All assuming we started with NPN xstrs.

I use it on my current nixie clock kit:

[Bill van Dijk]

Have a look at the ULN series chips, such as the ULN2003A or the ULN2803A. Cheap from Epay.

 

Bill

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[jpeakall]

If you are looking to reduce the pin count from the mcu, look at the 74HC595. Uses three mcu pins and can be cascaded for as many digits as you like, using only three pins. They are an SPI device so every mcu has some sample code kicking around.

Jonathan.

[David Forbes]

SN75468

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David Forbes, Tucson AZ

[Mitch]

Thanks for the comments and advice. After running out of memory on the Aurduino Micro, I'll switch to the mega 1284P so pins are not a problem. 

[Mitch]

This is the final version, although I'm still finding software bugs!

Tubes left to right are IN-14, IN-8-2, three Z573M, IN-12B, and National NL-8522. 

I plan on building eight clocks for family and friends. With top view tubes, I'll use INS-1 neons.

A matching acrylic cover fits on base.

Thanks to everyone who helped with advice and suggestions.

Mitch

[MichaelB]

Somebody has a Greyhound...

[Mitch]

One rescue, one foster. Zev and Sabina.

[gregebert]

Thanks for the picture. I dont see many clocks that use different tubes.

I'm going to take this as a suggestion and see how it looks on my big clock.

[Mitch]

Greg, I don't plan on keeping it that way, except maybe the smaller Z570M series for seconds. I'll see how it looks.