How to Minimize the Humming Noise of Omnixie and Omnixie Plus Clocks

Some of you may have noticed the humming noise of Omnixie/Omnixie Plus nixie clocks, or other nixie clocks with adjustable brightness feature, especially during nighttimes when the clock is located in your bedroom. Although some may think it is barely noticeable, others can get annoyed by the noise, as hearing capability differs among people. This article discusses the principles and provides two solutions to minimize the humming noise.

 

Our Omnixie and Omnixie Plus clocks allow users to adjust the brightness of the tubes. This is achieved using PWM (Pulse Width Modulation), which is a common way to control dimming of LEDs, or the direction of a servo. During PWM, the digital signal is turned on and off repeatedly at a high frequency (thousands Hz). By manipulating the percentage of the ON time vs OFF time, named “duty cycle”, one can achieve analog-equivalent voltages on the tubes, therefore adjust their brightness.  The side effect of PWM technique is the humming noise created by the rapidly switching of the voltages.

 

There are two ways to keep the humming to its minimal level. Both methods apply to all Omnixie and Omnixie Plus models, regardless of their tube types or enclosure materials (obviously).

 

1. Setting the tubes’ brightness to the maximum will largely minimize the humming noise. Here is how.

• When the clock is on and displaying time, press the Light button on the remote several times until 8 is flashing. 
• Press OK button to confirm. 
• Now the tubes are at the maximum brightness. 
• In case you need to change it back to automatic brightness based on ambient light, repeat the first step until six 0’s are shown and press OK to confirm.

2. Another way to lower the humming noise, is to change the switching effects of the digits to “jumping to the next digits directly without any fading in/out effects”. This can be done following the directions below.

• When the clock is on and displaying time, press the Func button on the remote to enter the menu system.
• Press the right arrow (=>) button multiple times, until the first two digits show 06.
• Press SET button.
• Press left or right arrow until the rightmost digit changes to “1”. The digit in the middle will show the actual current effect.
• Press OK to save/confirm.
• Press Cancel to exit the menu and return to the clock display.

After setting up the clocks with these two methods, the humming noise should be minimal.