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.

  • 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.

Can't get decade counter to work

Status
Not open for further replies.

Axe_Murderer

New Member
I'm trying to use a 4017 decade counter to cycle through a nixie tube display. Basically a seconds counter. I can get it work great just lighting up some LEDs, but when I connect the nixie instead the counter just stops counting. This should be simple, but... [banghead].

What am I doing wrong?
Thanks.
 

Attachments

  • nixie_problem.GIF
    nixie_problem.GIF
    4.9 KB · Views: 694

nettron1000

New Member
Im not sure of the proper drive voltages for the nixie, but im thinking its either insufficient drive from the transistor or incorrect polarity. Have you tried replacing the 10K resistor with a lower value ? Also , try using a PNP transistor.
 

Roff

Well-Known Member
I don't know why your counter quits, but I do know that you may have already damaged your Nixie tube and/or your MPSA42 if you truly don't have a current limiting resistor (47k may not be the optimum value) for the Nixie tube. I also corrected your clock input circuit, which presumably was just drawn wrong. See the schematic below.
 

Attachments

  • nixie_problem_172.gif
    nixie_problem_172.gif
    5.3 KB · Views: 581

Sebi

Active Member
I don't understand one thing: the nixie tube is like a glimm, neon filled tube with number-form anodes. With (about 80...100V DC) light only the anode.So the common cathode must be connected to negative (GND), and the switch must be on positive side....
 

nettron1000

New Member
The problem is with the 4017 not counting. The nixie lights up okay.

In your original post you said the counter worked fine when driving LEDs so im assuming the problem is with the nixie or its driver. Do you have any info on the type of nixie you are using ? is there something written on it ?
 

Roff

Well-Known Member
Sebi said:
I don't understand one thing: the nixie tube is like a glimm, neon filled tube with number-form anodes. With (about 80...100V DC) light only the anode.So the common cathode must be connected to negative (GND), and the switch must be on positive side....
Sebi, I looked at every datasheet on this site, and all of them were common anode. However, I did find **broken link removed** which implies that they make both versions.
 

Axe_Murderer

New Member
Okay, I figured it out with some prodding. Two things were wrong. First I added the 10k resistor as suggested above and it did help. Even with LEDs it was unstable, but that resolved it. However, when connecting the nixie it would count at 60Hz instead. Apparently there is some ripple coming from my 230v PS. :oops: In any case I also found that my 1Hz signal was too weak. After reconfiguring that things are much better.

It is still a little unstable. Everyonce in a while I'll notice a digit staying on for two seconds or maybe skip a digit instead. Every time I start a project like this I wish I had an ocilloscope...

For the record, my nixies are common anode and I know about their current limits. :wink: Although they do look VERY pretty when you over-drive them. Bright orange with a blue halo. :wink:
 

Roff

Well-Known Member
Axe_Murderer said:
Okay, I figured it out with some prodding. Two things were wrong. First I added the 10k resistor as suggested above and it did help. Even with LEDs it was unstable, but that resolved it. However, when connecting the nixie it would count at 60Hz instead. Apparently there is some ripple coming from my 230v PS. :oops: In any case I also found that my 1Hz signal was too weak. After reconfiguring that things are much better.

It is still a little unstable. Everyonce in a while I'll notice a digit staying on for two seconds or maybe skip a digit instead. Every time I start a project like this I wish I had an ocilloscope...

For the record, my nixies are common anode and I know about their current limits. :wink: Although they do look VERY pretty when you over-drive them. Bright orange with a blue halo. :wink:
I can't see why 230v ripple should affect your counter. How do you develop +9V? And do you have a ground plane, or at least a decent ground bus on your board, with good power supply decoupling on the +9V supply?
 
Status
Not open for further replies.

New Articles From Microcontroller Tips

Top