• Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

Wanting to build a Nixie Calculator

Status
Not open for further replies.

nzoomed

Member
Im interested in Nixie clocks, but i thought a calculator could be a different project, as clocks are a bit tired for me.

Ive got a few 5870 tubes to use, so any suggestions on the best approach would be good.

I expect a 4x4 matrix or something similar would work well for the keypad with some cherry MX switches.

I am trying to find a decent calculator chip to use such as a TMS-0103.

Only problem is i think most of these chips are designed to drive a VFD or LED segment display so the signals are not compatible with a nixie driver, unless there is some way to convert the logic with a different IC, any resources would be good.
Ive seen a nixie calculator using a raspberry Pi, but i think this is an overkill for a calculator.

TIA, hopefully i can make something work :)
 

nzoomed

Member
Use a PIC, or other processor - or a development board like an Arduino.
Yes was looking at those options, I thought there may be some better ASIC's out there, but i dont think any are suitable for nixie use without converting the signal designed for a segment display first, I could probably use an arduino to do this, but if i go to all that trouble, i may as just well use an arduino for the whole project, unless I can make a better functioning calculator with the functions in an ASIC.
 

KeepItSimpleStupid

Well-Known Member
Most Helpful Member
RPN calculators are so much easier to implement. The Arduino would give you transcendental functions. So, define your calculator. I made one that could do things like 8000 A 1 cm * 1 um /. I also supported ^ and PI. This was to enter cross sectional area divided by length in the units they were measured and converted to cm. People ended up making a lot less mistakes.
 

nzoomed

Member
RPN calculators are so much easier to implement. The Arduino would give you transcendental functions. So, define your calculator. I made one that could do things like 8000 A 1 cm * 1 um /. I also supported ^ and PI. This was to enter cross sectional area divided by length in the units they were measured and converted to cm. People ended up making a lot less mistakes.

I dont know much about RPN calculators, I just wanted to do a basic calculator with addition, subtraction, division and multiplication etc.
a % and memory function would be an advantage, but not necessary.

A scientific calculator would be much more complex, and i believe its not that simple to handle decimals or division without a remainder on an arduino.

I have no experience with programming in C so would need someone to help me write any code i use.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
I dont know much about RPN calculators.
You don't really want to :D

It's a crude and nasty system :D, which although makes it easier to program the chip, but makes it far more difficult to use.

Rather bizarrely HP made RPN calculators for years. If you're used to programming in Forth, then you are already used to RPN.

Considering the incredibly low spec of processors used in calculators it would be simple to do it with a PIC or AVR.
 

nzoomed

Member
You don't really want to :D

It's a crude and nasty system :D, which although makes it easier to program the chip, but makes it far more difficult to use.

Rather bizarrely HP made RPN calculators for years. If you're used to programming in Forth, then you are already used to RPN.

Considering the incredibly low spec of processors used in calculators it would be simple to do it with a PIC or AVR.

Well im wondering if its just easier to use an ASIC like i mention, but i will have to program a PIC for handling the Nixie tubes, i still dont know how to go about this although i have the general idea when ive seen how someone has done it with an alarm clock to nixie conversion, but this will be different as its handling decimal points in addition to the 7 segment displays.
 

KeepItSimpleStupid

Well-Known Member
Most Helpful Member
RPN: https://en.wikipedia.org/wiki/Reverse_Polish_notation

In general when you have parenthesis, you have an order of operations imposed. There are some simple calculators that don't have parenthesis. They generally have store and recall functions. Some have a SUM to location and negate to location. For the processor to evaluate an expression Infix is converted to postfix.

When you use RPN, you don't need parenthesis. You, maybe non-instinctively, evaluate from the "middle" or the most embedded parenthesis outward.
 

KeepItSimpleStupid

Well-Known Member
Most Helpful Member
BCD is a common denominator, of sorts. You can multiplex or not and you generally have to implement leading zero suppression. So, you have a BCD to 7 segment decoder/driver. Nixies would require a BCD to decimal decoder driver. There is no reason, that you could not create, if necessary, a 7-segment to decimal decoder driver or even convert from a multiplexed seven segment display to a multiplexed BCD display and finally to a multiplexed 1-10 decoder.

Since the Nixies are neon bulbs, there is a way where there is a sustaining voltage that can be applied where the digits won't change. Briefly going above/below the threshold turns the segment on/off. Not exactly sire if this works with multiple segments.
 

Les Jones

Well-Known Member
Most Helpful Member
When I built my first frequency counter which used nixie tubes (Over 40 years ago.) the standard way to drive them was using a SN74141 BCD to high voltage decimal output. Farnell and RS do not stock them but some sellers on ebay have them. (At a high price.) I still have this frequency counter and it still works.

Les.
 

nzoomed

Member
OK, so the SN74141 is what is used for decoding the 7 segment signal to BCD for nixies?

Ive seen this chip mentioned alot, and i just thought it was for driving each cathode directly without the need for high voltage transistors, but it appears it does much more than this.

Im not sure if i will use multiplexing or not yet, but it does lower the component count.

Ive also found this schematic with the chip im looking at using
http://www.cs.ubc.ca/~hilpert/eec/calctd/CommodoreC110.gif
 
Last edited:

BobW

Active Member
Unfortunately, that chip is designed to work with a multiplexed seven segment display. In order to use it with nixies, you would have to undo all of the output multiplexing, which would be a major ordeal. Is the TMS0103 even available anymore?
 

KeepItSimpleStupid

Well-Known Member
Most Helpful Member
Im not sure if i will use multiplexing or not yet, but it does lower the component count.
I just read an article that multiplexing doesn't work for Nixie like tubes. See Nuts and Volts mag Sep 2016, p6 "Build the Numitron A Six-Digit Clock. It's part LED and part Numitron which is essentially a 7-segment Nixie which is probably more readable.
 

BobW

Active Member
I don't particularly like to multiplex Nixies, but I know that others have done it. So, I'm curious what they say the problems are. For driving Nixies there are some very nice serial-in, high voltage parallel out shift registers available that drive the Nixies continuously (no multiplexing). They are a bit more pricey than lower voltage devices, but IMO, the simplicity and reduced component count more than make up for the extra cost. For example, the Supertex HV5812 is a 20 bit HV parallel output driver that will drive two Nixies, and you can daisy chain them together so that you only need two or three I/O lines from your microcontroller to control any number of Nixies.
 

RODALCO

Well-Known Member
Sometimes you can find genuine 74141 IC's on eBay, often the Russian K155ID are sold, not sure how good they are but the prices are reasonable.
2016-08-26_18-01-46.jpg
 

nzoomed

Member
OK, so the SN74141 is what is used for decoding the 7 segment signal to BCD for nixies?

Ive seen this chip mentioned alot, and i just thought it was for driving each cathode directly without the need for high voltage transistors, but it appears it does much more than this.

Im not sure if i will use multiplexing or not yet, but it does lower the component count.
Unfortunately, that chip is designed to work with a multiplexed seven segment display. In order to use it with nixies, you would have to undo all of the output multiplexing, which would be a major ordeal. Is the TMS0103 even available anymore?
well i just saw that one on ebay, is there another chip you suggest?
I see a few on ebay, but i cant find the datasheets etc.

As far as multiplexing goes, alot of clock kits seem to do this from what i see.
I think the main issue is the brightness level is affected.
 

RODALCO

Well-Known Member
The 74141 can sink open collector 60 Volts of memory at 7 mA.
Nixie tube anodes at + 175 Volts DC
Current limiting resistor usually 15kΩ
 

nzoomed

Member
The 74141 can sink open collector 60 Volts of memory at 7 mA.
Nixie tube anodes at + 175 Volts DC
Current limiting resistor usually 15kΩ
Gidday Rodalco!
Im a subscriber to your channel!

I live in Tauranga BTW ;)
Send me a PM and ill send you a link to my tesla coil in action.

Anyway, do you have much experience with Nixie tubes?

Im trying to work out if i can find a more suitable chip to use since the calculator IC i was looking at is putting out a multiplexed signal.
 

RODALCO

Well-Known Member
Have built a small Nixie clock about 30 years ago. worked well but used the 74141 chips in a non multiplexed way.
I have schematics somewhere how to built that.
As far as I know Nixies don't like multiplexing as it takes a few milliseconds for the Neon gas to ignite in the tube.
 
Status
Not open for further replies.

Latest threads

EE World Online Articles

Loading
Top