IN-18 Nixie Tubes only partly illuminating

[Christine Thompson]

Hello people,

I have recently discovered the world of Nixie tubes. 

My first clock was based around 6 x IN-12 and 2 x IN-15A tubes, controlled via 8 x K155id binary converters, using an Arduino Mega 2560. 

Powered by a 12v to +200V DC-DC Boost Converter.  All of the above worked fine with acceptable brightness of the tubes. 

The photo is the DC-DC boost converter I am using.

I use Direct drive to power the tubes, having a separate 12V to 5V step down converter to supply the 5V for each K155id converter and the Arduino Mega.

 

I have now moved onto my next clock which is largely based around the first clock with the exception that I am using 6 x IN-18 tubes. 

Wiring and testing each tube, using 170V as the Strike Voltage and touching each pin with the cathode with a 20K ohm resistor in series,

confirmed that each digit lit to an acceptable brightness.

With the clock fully wired and powered using the same 12V to +200V DC-DC boost converter, I have set the output voltage to 170V, 

however some of the tube’s digits do not fully illuminate, especially the 8 and 9, similar to cathode positioning.  What I have found is 

that no matter what I set the DC-DC boost converter to, as output voltage, a multimeter only reads 148V, with an anode voltage of 130V to 133V, 

based on each anode having a 20K ohm resistor in series.  

I believe that if I could increase the anode voltage from say 130V to between 140V to 150V this problem of partial illumination will be corrected. 

I also suspect that the DC-DC Boost converter I am using cannot supply the necessary current in order to support these six tubes.My understanding

is that these tubes need typically 6.5mA. 

I only have a very basic multi-meter and no oscilloscope.

I would be most grateful for any help with the above, I am sure that extra information is necessary, so happy to provide it.

[John Rehwinkel]

With the clock fully wired and powered using the same 12V to +200V DC-DC boost converter, I have set the output voltage to 170V, 

however some of the tube’s digits do not fully illuminate, especially the 8 and 9, similar to cathode positioning.  What I have found is 

that no matter what I set the DC-DC boost converter to, as output voltage, a multimeter only reads 148V, with an anode voltage of 130V to 133V, 

based on each anode having a 20K ohm resistor in series.

I suspect you're correct, and the power supply simply isn't capable of supplying enough current.  You could either replace it with a more powerful model, or simply obtain a second one and use each one to run some of the tubes.

- John

[严泽远]

You got the fake DC-DC power supply, it’s the copy of my design, cannot provide enough current for tubes, please check details here:
http://www.nixieclock.org/?p=1338

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Hope it will helps.
Thanks.
Yan.