We have completed a DCDC converter that generates the high voltage required for Nixie tubes from 5V. Here's a look at the process of making it.
The PCB and stencil arrive from Fusion PCB
JLCPCB seemed to charge more for more end-face through-hole surfaces, so I had the PCB and stencil made by Fusion PCB, where the cost is constant.
Compared to JLCPCB, the board and silk are much cleaner.
A discarded PCB of the same thickness sandwiches the front and back.
For the stencil and the board, make the data in advance to make holes around the stencil. By sticking a thumbtack in those holes, you can align the board and stencil accurately and easily. In my experience, 1.0 mm is the best diameter for the holes.
Place the solder paste on the stencil. If you mix the solder paste in a container for a few minutes to make it smooth, it will be easier to fit into the fine holes of the stencil and print beautifully.
Using a plastic card as a squeegee, move it toward you at a speed of about 1cm/second to print the solder paste.
The solder paste was printed at the exact position.
Mounting components with HAKKO 394
Surface-mounted components are mounted with the electric vacuum pick HAKKO 394. I definitely recommend it because it is super convenient and easier to mount than tweezers. Think you have been tricked and try it. You will never be able to go back to tweezers.
Press the button on the HAKKO 394 to activate the pump. In this state, suck the parts from the reel tape to the tip of the nozzle.
When the part is moved to the desired position, place the part on the board and release the button. The pump will stop and the part will be released.
The white object on the left of the photo is an SMD feeder printed with a 3D printer (a jig that holds the tape in place). By picking up the parts directly from the tape, it is very easy to always pick the parts in a certain direction. For more information, please see this article👇.
Reflow with hot plate
I reflowed with a hot plate. A thermocouple thermometer would have been useful to know the temperature.
Currently, I am reflowing with a convection oven. It is more efficient.
Using a specially made jig, I check if the DCDC converter is working properly. Everything was OK.
I would like to check the characteristics to see how much load it can actually withstand.
Attach a pin header so that it sticks to the breadboard.
Connect more and more resistors in parallel to the output, and measure the resistance value, output voltage, and input current.
Here are the measurement results. On the left is the characteristic of the output current and output voltage, and you can see the voltage drop after 5mA. The Nixie tube needs about 160V, so 5mA is probably the maximum.
The right graph shows the current consumption and efficiency. Pink is current consumption (left axis). Orange is efficiency (right axis). As the output current increases, the current consumption increases. This is normal. The efficiency is constant at about 50%.
This DCDC converter is equipped with a volume control for voltage adjustment. The minimum voltage is about 175V, but if the voltage is not enough, you can increase the voltage by turning this volume counterclockwise. You can increase the voltage up to about 220V. However, the current that can be drawn will be lowered.
DCDC converter for Nixie tubes completed!
The DCDC converter for the Nixie tubes was completed! The Nixie tube shines well. If you have a high voltage power supply, you can easily experiment with Nixie tubes.
If you touch the output, it will chatter, so be careful not to touch or short-circuit it.