REPLACEMENT OF Q3 = DIMMER DIGITS

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N6BM
 
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REPLACEMENT OF Q3 = DIMMER DIGITS

Post by N6BM »

My Ice Cube clock required a jumper between pins 1 & 3 until Q3 could be replaced as I had flickering digits. With the jumper in place, all six digits were equally bright until I replaced Q3 today. With Q3 replaced and the jumper removed, the first five digits are equal in brightness but the last (seconds) digit is definitely dimmer (1/2 brightness). No flickering digits so the replacement of Q3 is working. I have the brightness at the lowest level (40).

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adafruit_support_bill
 
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Re: REPLACEMENT OF Q3 = DIMMER DIGITS

Post by adafruit_support_bill »

The dimness of the seconds digit is normal and described in the FAQ. It has to do with the way we drive the tube. There are several hardware and/or firmware-based workarounds for this developed by users and posted in the forum.

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phild13
 
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Re: REPLACEMENT OF Q3 = DIMMER DIGITS

Post by phild13 »

Here is an excellent post about Q3 where we discuss replacing Q3 with other options.
viewtopic.php?f=41&t=51283

Short answer is to replace the stock ZVP3306A (Q3) with a ZVP2110A FET, or a PN2907A transistor with either a 1k or 470 ohm base resistor (both work well and any value in between those two values will also work well) soldered to the middle leg. This post describes how to solder the resistor to the transistor so it looks good.. http://forums.adafruit.com/viewtopic.php?f=41&t=43908.

I have used both ways of replacing the stock Q3 and both ways work equally well.

Another thing that is not necessary but can be done in addition to replacing Q3 with a better performing component is to replace R3 (22 ohm) with an 11 ohm resistor or a jumper wire. This will increase the current to filament some. I would recommend this mod only if you have replaced the Q3 with a better performing component.

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jarchie
 
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Re: REPLACEMENT OF Q3 = DIMMER DIGITS

Post by jarchie »

I can second Phil's advice. I've personally tried both of the solutions he suggested, and both solve the annoying dim-final-digit issue.

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MikeHg
 
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Re: REPLACEMENT OF Q3 = DIMMER DIGITS

Post by MikeHg »

I also use the the N2907A as adviced by Phil and I'm totally happy with it. This transistor together with a 1k resistor works very well since some weeks now whereas before I had quite a nightmare with the ZVP3306A.

Best regards,
Mike

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