Problem with Arduino Nixie Clock

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1 month 1 day ago #12713 by KRiZ
Hi,
I do have an old scope, but I am not very familiar with using it, but I am willing to learn :)
So maybe you can see something on the pictures.


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1 month 20 hours ago #12715 by Ty_Eeberfest
Looks to me like you're using the scope just fine :) The only thing that's not clear to me is the amplitude of the pulses. I see that it's set for 5V/div but the graticule (division lines) isn't visible. Can you tell if the pulse amplitude is about 5 volts? I'm thinking it probably is but would like to be sure.

The frequency looks okay but the duty cycle looks wrong: too much on time, which would tend to make things get hot. I'm going to change my mind here and blame the inductor regardless of what the LCR tester said. It looks like the Arduino is trying hard to pull up the high voltage, by applying max duty cycle to the MOSFET gate, but the voltage isn't coming up.

Hopefully Ian will look at this thread today and let us know if he thinks we are on the right track. It is, after all, his circuit,

Look into it later when the dust is clearing off the crater.

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1 month 18 hours ago #12716 by KRiZ
Hi,

I have edited the pictures, the division lines are where the red line is.
Ik have put the scope on 5V, so the amplitude is on or a bit above the 5V line.
Thanks again for checking this out!


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1 month 18 hours ago #12717 by Ty_Eeberfest
Okay, I get it now. I've never seen a scope that displays its grid that way. I'm just accustomed to the "normal" way as seen in my scope shots above.

I'd suggest replacing the inductor. That's the only thing I can think of at this point.

Look into it later when the dust is clearing off the crater.
The following user(s) said Thank You: KRiZ

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1 month 17 hours ago #12718 by KRiZ
Thanks,
my scope is probably a museum piece :)
As I also own an analog scope, which is probably even older and was even less usefull now.
I will try to find an inductor with 150uH to replace it.
Do you know what specs I need, because there are so many different sorts of them.

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3 weeks 3 days ago #12720 by KRiZ
Hi,
I have found an 150uH inductor, I could not find the same model for quick delivery, so I don't know if this one should also work. See attached pictures.
I have tested it with the new inductor and a new mosfet. The bulbs go on and display the numbers, but after about 20 seconds, the mosfet begins to smoke, and it will die. It has also burned 2 inductors and killed an arduino.
I have tried 640,740 and 840 mosfets.
The frequency from the arduino was the same as last time. The 170V pin was about 173Volt.


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