High Voltage Trouble shooting.

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1 year 5 months ago #9939 by Malugalugalugalugaluga
What are the mosfet mounting suggestions for the arduino six digit nixie driver. I had some issues with my previous mosfet, it would only turn the clock on if I touched it. So I replaced it with a new one and now nothing.

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1 year 5 months ago - 1 year 4 months ago #9940 by Malugalugalugalugaluga
Help can't get my arduino six digit clock to work. I suspect something isn't right with the one or both mosfets. Here's a rundown of voltages on the mosfets.

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Last edit: 1 year 4 months ago by Ian.

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1 year 5 months ago #9944 by Ty_Eeberfest
I moved a couple of your posts to a more appropriate place where they are more likely to get responded to. Your new thread title is "High Voltage Trouble shooting"

Looking at your sketch I notice there isn't any gate drive on Pin 1 of the IRF840. The signal that should be there is 5V PWM at a pretty high frequency (~32KHz) but you should see at least something there on your DC voltmeter. This is the signal called HVD on the schematic. It comes from Pin 15 on the Atmega.

The voltage on Pin 3 of the 7805 is a bit high but not scary high. I would expect more like 4.95 - 5.10 volts there. Is Pin 2 solidly connected to ground? Pin 1 voltage is getting close to the too-high limit, but this should not affect the Pin 3 voltage. I'm guessing you are using a 12V power supply (which is fine) that's unregulated or poorly regulated (which is not the greatest way to go, but probably won't hurt anything). I'd recommend a better power supply just on general principles.

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

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1 year 5 months ago #9945 by Ty_Eeberfest
Regarding your mounting question, I answered that on one of your other threads, but in short: it's fine to have the devices just standing on their pins as in the photos. Heat sinks are optional and not usually needed. It is critical that you do NOT do anything that would connect the metal tabs of the 2 devices together!!!

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

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1 year 4 months ago #9969 by Malugalugalugalugaluga
Thank you for the reply. It says .10v at pin 15. Also the power source is 12v 300ma.

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1 year 4 months ago #9971 by Ty_Eeberfest
Are you absolutely sure you didn't damage a trace on the board when changing the MOSFET? With power off, check for continuity from MOSFET Pin 1 to Atmega Pin 15. There needs to be good continuity, basically 0 ohms. If no continuity then you need to find the cut trace...

That power supply is right on the edge of being too small. 12V and >= 500mA would be better.

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

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