HV Nixie DC-DC Switching Power Supply

  • Michail Papadimitriou
  • 65028
    Views
  • moderate
  • Tested
  • Buy Now

Nixie tubes need about ~180Vdc to light up and thus on most devices, a DC-DC converter is needed. Here we designed a simple DC-DC switching regulator capable of powering most of Nixie tubes. The board accepts 12Vdc input and gives an output of 150-250Vdc.

Description

The module is based on the MAX1771 Step-Up DC-DC Controller. The controller works up to 300kHz switching frequency and that allows the usage of miniature surface mount components. In the default configuration, it accepts an input voltage from 2V to Vout and outputs 12V, but in this module, the output voltage is selected using the onboard potentiometer and it’s in the range 150-250Vdc. The maximum output current is 50mA @ 180Vdc.

The MAX1771 is driving an external N-channel MOSFET (IRF740) and with the help of the inductor and a fast diode, high voltage is produced.

MOSFET has to be low RDSon, the diode has to be fast Mttr, typically < 50nS, and capacitors have to be low ESR type to have good efficiency.

Precautions must be taken as this power supply uses high voltages. Build it only if you know what you are dealing with. Don’t touch any of the parts while in use.
Pay attention on the placement of C1 tantalum capacitor, as the bar indicates the anode (positive lead)

Schematic

Parts List

PartValueLCSC.com
R11.5M - 0805 SMDC118025
R310k 0805C269724
R45k trimmer SMDC132878
Rs0.05 Ohm - 0805 SMDC149662
C1100uF Tantalium SMDC444810
C2-C3100nF - 0805 SMDC116832
C44.7uF / 250V SMDC88702
C5100nF / 250V SMD 1210C76688
ICMAX1771 SO-8C407903
L1100uH / 2.2 AC429814
Q1IRF740 D2PAKC467558
D2ES2F-E3C145321
X1-X2screw terminal Pitch 3.5mmC474892

Oscilloscope Measurements

Yellow is the MOSFET Gate voltage and Green the output high voltage (~180Vdc). We see that the transistor switches with a low frequency of 146Hz and with a peak gate voltage of 12.8V
zoom in to the above short pulses reveals 3x pulses with 48.7Khz frequency to the gate of MOSFET. Also, the peak to peak ripple on output is 6V
further zoom to the output ripple reveals some short ringing and the peak ripple voltage.



Efficiency

The module’s efficiency is calculated for two outputs currents (50mA and 25mA) at 180Vdc voltage output and 12V input. In the first case, the Pout = 8.1W while the Pin=10.96W, so efficiency is calculated at 47.75%. In the second case, the Pout = 4.1W while the Pin=5.52W, so efficiency is calculated at 74.54%. We see that for lower currents efficiency is greater than for the maximum current of 50mA.

Photos

If you would like to receive a PCB, we can ship you one for 6$ (worldwide shipping) click here to contact us

MAX1771 Datasheet

MAX1771

PCB

Subscribe
Notify of
guest
27 Comments
Inline Feedbacks
View all comments
Francois

Hi, what is the nominal and or maximal output current @ 180V ?
And you say that i can be powered from 2, to 16.5V. Is it really 2v or 12V ?
Thank you !

ZF

Poor Layout

Dustin Williams

where is your design ZF

Julian Lützen

I think it’s better to have more clearance to GND at the HV Output at the bottom side of your PCB. It seems there is a distance of less 1mm to GND. I would let end of the GND polygon about 1cm before the HV Connector and connect the HV-GND Pin with a single strip to the polygon. It feels a bit safer this way.

spvoile

Hello, I am not an expert in mosfets but I wanted to know if I can replace the IRF740ASTRLPBF with IRF740STRLPBF (same reference without the “A”). The datasheet is quite similar and I don’t know if the difference matters for this application…

Yodee

Hello!

I would like to use this project, but I can’t open the eagle file. It is corrupt. Can You help me?

Thanks

Yodee

Unfortunetly still wrong. Eagle 7.6 and EasyEDA still can’t open the .brd file.

Yodee

In EasyEDA when I try to import the .brd, it says:

“Unexpected error while converting. Perhaps unsupported file type or program bug”

Can You open it in EasyEDA?

Yodee

It works! Thanks!

Yodee

Mike!

Can this power supply do 180V 30-35mA with 12V in?

Yodee

And What about heating?

Yodee

Perfect. The PCB already here, i waiting the components. I hope it will be good for me.

Yodee

Dear Mike! I set up the power supply.On my 6 tube nixie clock the values are this:

In the morning, when 5 tube is in work (0:00 – 9:59) the current is 15-18mA @ 180V
After that (10:00-23:59) when all the 6 tubes are in work the current is 19-22mA @ 180V. The Induction is getting hot. Is this normal, or i make something wrong?

Thanks

Yodee

~50°C in 30 minutes

Yodee

Which type / size?

pcbbc

Just to say thanks very much for providing this design and the parts list.
I’ve now completed my FLW project that I purchased the tubes for back in 2016.
Two of these circuits on the PCB driving 2 B-7971 tubes each.
Almost 180V right out of the box because the 5K trimmers were supplied centred. Nice!

RELATED PROJECTS

X
ADP3450 Oscilloscope Giveaway

By continuing to use the site, you agree to the use of cookies. more info

The cookie settings on this website are set to "allow cookies" to give you the best browsing experience possible. If you continue to use this website without changing your cookie settings or you click "Accept" below then you are consenting to this.

Close