Arduino IN-14 Nixie Operating Instructions Manual page 16

Once all the components are on the board, hook up the power. Give your work a careful check to make
sure that the orientation of the components is right. Especially check that the stripe on C1 is facing the
marking on the board.
Be careful, we are dealing with high voltages now!
The voltage may be significantly higher than 170V at the moment, because the high
voltage generator is powerful and the output is not loaded. Once you add a load, (by
connecting the tubes), the voltage should oscillate around 170V – 190V, and might have a
Warning! slight "sawtooth" appearance if you view it with an oscilloscope.
Apply power to the board again. Listen for any stressed sounding buzzing or humming,
and check that neither the 7805 nor the MOSFET get excessively hot.
Check that the power LED still lights.
Test Step
If you hear any angry sounding buzzing turn the power off immediately and check
the orientation of C1! The circuit should run almost silently, with only a very faint
"crackling" sound.
Trouble
If you can't reach the target voltage, turn off and check the polarity of your components,
shooting
especially C1. If you have an oscilloscope, you can check the voltage at the gate of the
MOSFET, and it should show pulses of high frequency square wave: this is the driver
waveform to the HV generator, which is being turned off and on by the voltage detection,
trying to achieve the target voltage (180V default).
Note also that the "Power" header also has high voltage exposed on it!
This is for if you want to drive neons instead of LEDs for the colons. Be careful handling
the board, it is easy to touch the "Power" header by mistake. If you are sure you won't be
needing it, you can snap the extra pin off and populate only the bottom 3 pins on the
Warning! connector.
Check the voltage at the 170V test point. You should read a voltage in excess of 170V.
You can also test using an old neon lamp if you have one. Temporarily connect the neon
lamp between the "GND" test point and the "170V" test point with an appropriate ballast
Test Step
resistor (turn the power off first). Turn the power on and the neon lamp should come on.
Q1 can get warm, but should not get too hot to touch. If it gets hot, you need to check
the orientation of the components and that there are no solder bridges.
If you don't get the expected voltage reading:
Trouble
shooting
•
•
•
•
Check your soldering that there are no bridges or dry joints.
Check that the external power supply is able to supply the power needed to
achieve the high voltage: check that the VIN voltage is stable and not fluctuating.
Temporarily connect the LDR and re-test.
Temporarily connect the button and do a factory reset