Fitting neon colon separators. IN-14 All in one Arduino clock

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2 months 5 days ago #12046 by Ty_Eeberfest

Chesful wrote: Ok, I've found the problem.
I was using another 2N7000 in Q6 instead of the MPSA42. Obviously, I've surpassed the Drain-Source breakdown voltage with the neons and broke the transistor. That's why my neons were so bright and didn't "blink" (they where always with the same brightness, I've should have stated it more clearly in my first comment).
Also, I've should have checked before the datasheet of the component. Although it is said clearly in the construction manual, the schematics show that Q2, Q4 Q5 & Q6 are all 2N7000 and thus, my confusion.
Now that I've replaced it, it works perfectly.


Ian please take note. He has a valid complaint there about the schematic and manual. It's never really stated that you need a MPSA42 if using neons.

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

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2 months 4 days ago #12048 by Ian
Yep, on it.

That's really annoying. Going to check the manuals now... Originally they were all 2N7000, but when I started to use neons, I had to up the voltage rating. 200V FETs are kinda hard to get, but the MPSA42 is plentiful and cheap.

Interestingly, the base resistor must also be missing.

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2 months 4 days ago #12049 by Ty_Eeberfest
Yeah looks like a classic case of updating but missing a couple things. For example the schematic has a BJT symbol but an FET part number. Shit happens. If it was up to me I'd mention it explicitly in the text as well since currently only FETs are mentioned.

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

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