Nixie-Clock-IN-12 Clock Is Extremely Warm

[Dman777]

I have this clock and have had it for about 3 months now:

http://www.ebay.com/itm/Nixie-Clock-IN-12-Six-Digit-TubesTube-Clock-with-smoke-case-remote-RGB-Leds-IN12-/271174922160?pt=US_Digital_Clocks_Clock_Radios&hash=item3f2348efb0

Tonight I was moving it around and I noticed that the left side of it is extremely warm.....enough to heat the wooden shelf where it sits. Is this considered normal? 

Thanks,

-Darin

[Niek]

From looking at the schematics you provided in an earlier post about the flickering issue, it's probably caused by the SMPS (switched mode power supply) that provides the high voltage (around 175V) to the nixies. It's using a 34063, which can't drive a mosfet very well by itself: ideally you would add a PNP transistor to its gate to make sure it can switch off quickly. This would make it much more efficient, and therefore waste a lot less energy as heat. As before, you can see that the design for this clock is not really great, giving the issues you're finding.

Here's an example of a design that incorporates the PNP to switch off the mosfet quickly:

http://threeneurons.wordpress.com/nixie-power-supply/hv-supply-kit/