Author Topic: MC34063 based Nixie tube power supply oscillations  (Read 6782 times)

Offline ntoskrnl

  • High Voltage Enthusiast
  • *
  • Posts: 5
  • Karma: +0/-0
    • View Profile
MC34063 based Nixie tube power supply oscillations
« on: May 11, 2017, 02:45:36 PM »
I built a Nixie tube clock with an MC34063 based switch-mode power supply for the tubes. The input voltage is 12V and the output is 180V. Here's the schematic:



The circuit was mostly inspired by this page: https://threeneurons.wordpress.com/nixie-power-supply/

The power supply works perfectly. However, it has a rather low efficiency (around 50–60%), and when I looked at some voltages with my oscilloscope, I noticed some oscillations that should not be there.

Vds of Q1:


(Vdiv: 50, tdiv: 10µ)

Pin 2 of U1:


(Vdiv: 2, tdiv: 5µ)

The circuit works by switching the FET approximately 2–3 times quickly in succession and then waiting a little longer before repeating. This is why the waveforms look a bit weird on the oscilloscope. However, my concern is the oscillations that happen after these 2–3 pulses. (Maybe the notches on the falling edges of the pulses are also related?) These turn the FET partially on and cause significant power loss.

The oscillations seem to be coming from the chip rather than from around Q2/D2/R1. What could possibly cause this? Coupling from the inductor maybe, but where?
« Last Edit: May 11, 2017, 02:49:57 PM by ntoskrnl »

Offline Mads Barnkob

  • Administrator
  • High Voltage Expert
  • *****
  • Posts: 1232
  • Karma: +17/-0
  • Denmark
    • View Profile
    • Kaizer Power Electronics
Re: MC34063 based Nixie tube power supply oscillations
« Reply #1 on: May 11, 2017, 07:02:52 PM »
Parasitic inductances in the circuit that oscillates with the gate capacitance, add a gate resistor to the MOSFET :)
http://www.kaizerpowerelectronics.dk - Tesla coils, high voltage, pulse power, audio and general electronics

Offline ntoskrnl

  • High Voltage Enthusiast
  • *
  • Posts: 5
  • Karma: +0/-0
    • View Profile
Re: MC34063 based Nixie tube power supply oscillations
« Reply #2 on: May 12, 2017, 02:09:30 PM »
Hmm, the frequency of those oscillations seems too low to be caused by that – the frequency is only around 400 kHz and I would expect gate capacitance oscillations to be in the MHz range. Or maybe they can be that slow?

There is also almost no ringing whatsoever on the rising edge of the gate pulse:


(Vdiv: 2, tdiv: 50n)

I could try adding a gate resistor, but it's a bit of a hassle. I wish I had caught this issue before I made the PCB... I also don't have any resistors between 1 ohm and 1 kohm at hand right now. But I guess it's worth a try if you think it will help?

Do you have any idea if it could be caused because I used a BC558 as Q2 instead of an MPSA55 as specified?

Edit: Oh my god. Q2 was installed backwards. I turned it around and now the waveforms are super sharp. I'm surprised the circuit even worked with the transistor backwards.

This seems like a curse. I don't think I've ever managed to finish a project without installing a transistor backwards. Not even double-checking seems to be enough.
« Last Edit: May 14, 2017, 04:58:46 PM by Mads Barnkob »

Offline ntoskrnl

  • High Voltage Enthusiast
  • *
  • Posts: 5
  • Karma: +0/-0
    • View Profile
Re: MC34063 based Nixie tube power supply oscillations
« Reply #3 on: May 12, 2017, 03:35:42 PM »
No, I spoke too soon... The gate waveforms and efficiency are better but there are still small oscillations which cause large oscillations in Vds:


(Vdiv: 50, tdiv: 10µ)

The frequency of those oscillations is still the same 400 kHz.

Offline T3sl4co1l

  • High Voltage Technician
  • ***
  • Posts: 111
  • Karma: +9/-0
    • View Profile
Re: MC34063 based Nixie tube power supply oscillations
« Reply #4 on: May 12, 2017, 11:20:37 PM »
That's the clamped oscillation of L1 with Q1 Coss.

Obligatory:
MC34063, really? ::)

Tim

Offline ntoskrnl

  • High Voltage Enthusiast
  • *
  • Posts: 5
  • Karma: +0/-0
    • View Profile
Re: MC34063 based Nixie tube power supply oscillations
« Reply #5 on: May 14, 2017, 09:31:38 PM »
Yep, I figured it's probably something that should be there because I get those oscillations even when simulating this circuit. There's very little current flowing through the FET during that so I guess it doesn't waste much power. I get around 75% efficiency now which is pretty good for an MC34063.

I'm using an MC34063 because I've heard it's easy to use with its very simple feedback loop. The circuit worked perfectly even on a breadboard and I didn't have to apply any black magic to my circuit board design. :P

Offline Mads Barnkob

  • Administrator
  • High Voltage Expert
  • *****
  • Posts: 1232
  • Karma: +17/-0
  • Denmark
    • View Profile
    • Kaizer Power Electronics
Re: MC34063 based Nixie tube power supply oscillations
« Reply #6 on: May 15, 2017, 07:21:03 PM »
Did you try to add a gate resistor? Just something really low like 1R
http://www.kaizerpowerelectronics.dk - Tesla coils, high voltage, pulse power, audio and general electronics

Offline ntoskrnl

  • High Voltage Enthusiast
  • *
  • Posts: 5
  • Karma: +0/-0
    • View Profile
Re: MC34063 based Nixie tube power supply oscillations
« Reply #7 on: May 15, 2017, 07:51:59 PM »
No, I didn't try that. But I tried it in the simulation and it didn't change anything. I will try it if I ever build a similar circuit on a breadboard again.

High Voltage Forum

Re: MC34063 based Nixie tube power supply oscillations
« Reply #7 on: May 15, 2017, 07:51:59 PM »

 


* Recent Topics and Posts

post Small DIY plasma globe using ZVS oscillator
[Transformer (Ferrite Core)]
davekni
Today at 06:21:31 AM
post Re: Mazilli ZVS Driver Modification Problems
[Transformer (Ferrite Core)]
Andrew321
Today at 05:54:17 AM
post Re: Mazilli ZVS Driver Modification Problems
[Transformer (Ferrite Core)]
Andrew321
Today at 05:45:43 AM
post Re: DSO138, Not Even Once
[Laboratories, Equipment and Tools]
Twospoons
January 21, 2020, 10:54:44 PM
post Re: DSO138, Not Even Once
[Laboratories, Equipment and Tools]
Mads Barnkob
January 21, 2020, 08:05:20 PM
post Re: DSO138, Not Even Once
[Laboratories, Equipment and Tools]
Mysteriousduck
January 21, 2020, 03:49:24 PM
post Re: DSO138, Not Even Once
[Laboratories, Equipment and Tools]
Mads Barnkob
January 21, 2020, 08:37:14 AM
post Re: DSO138, Not Even Once
[Laboratories, Equipment and Tools]
klugesmith
January 20, 2020, 11:10:05 PM
post Re: Mazilli ZVS Driver Modification Problems
[Transformer (Ferrite Core)]
T3sl4co1l
January 20, 2020, 10:55:35 PM
post Re: Mazilli ZVS Driver Modification Problems
[Transformer (Ferrite Core)]
davekni
January 20, 2020, 09:48:06 PM
post Re: DSO138, Not Even Once
[Laboratories, Equipment and Tools]
Twospoons
January 20, 2020, 08:31:54 PM
post Re: Mazilli ZVS Driver Modification Problems
[Transformer (Ferrite Core)]
SteveN87
January 20, 2020, 12:59:19 PM
post DSO138, Not Even Once
[Laboratories, Equipment and Tools]
Mads Barnkob
January 20, 2020, 11:13:23 AM
post Re: Welcome new members, come say hello and tell a little about yourself :)
[General Chat]
HVZapp
January 20, 2020, 10:23:03 AM
post Re: Mazilli ZVS Driver Modification Problems
[Transformer (Ferrite Core)]
Andrew321
January 20, 2020, 05:55:07 AM
post Re: Why does this happen.
[General Chat]
thedoc298
January 19, 2020, 09:43:26 PM
post Re: Why does this happen.
[General Chat]
Mads Barnkob
January 19, 2020, 09:07:51 PM
post JavaTC question
[General Chat]
thedoc298
January 19, 2020, 09:01:06 PM
post Re: Universal bus precharge & fan speed controller
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Hydron
January 19, 2020, 01:08:17 PM
post Re: Universal bus precharge & fan speed controller
[Dual Resonant Solid State Tesla coils (DRSSTC)]
futurist
January 19, 2020, 12:36:56 PM
post Re: 500Khz Induction Heater - Need help with Driver
[Beginners]
Mysteriousduck
January 19, 2020, 04:06:36 AM
post Re: Welcome new members, come say hello and tell a little about yourself :)
[General Chat]
rvpilot
January 19, 2020, 02:00:30 AM
post Re: 500Khz Induction Heater - Need help with Driver
[Beginners]
T3sl4co1l
January 18, 2020, 08:51:26 PM
post Re: 500Khz Induction Heater - Need help with Driver
[Beginners]
klugesmith
January 18, 2020, 06:53:02 AM
post Re: Welcome new members, come say hello and tell a little about yourself :)
[General Chat]
Mysteriousduck
January 18, 2020, 05:19:49 AM
post Re: 500Khz Induction Heater - Need help with Driver
[Beginners]
Mysteriousduck
January 18, 2020, 04:41:22 AM
post Re: 500Khz Induction Heater - Need help with Driver
[Beginners]
T3sl4co1l
January 18, 2020, 12:30:19 AM
post 500Khz Induction Heater - Need help with Driver
[Beginners]
Mysteriousduck
January 17, 2020, 11:17:33 PM
post Re: Energy and Efficiency
[Induction Launchers, Coil Guns and Rails guns]
klugesmith
January 17, 2020, 08:55:37 PM
post Re: Energy and Efficiency
[Induction Launchers, Coil Guns and Rails guns]
T3sl4co1l
January 17, 2020, 04:01:23 PM
post Re: Energy and Efficiency
[Induction Launchers, Coil Guns and Rails guns]
RobertL
January 17, 2020, 04:22:25 AM
post Re: Energy and Efficiency
[Induction Launchers, Coil Guns and Rails guns]
Twospoons
January 17, 2020, 01:37:37 AM
post Energy and Efficiency
[Induction Launchers, Coil Guns and Rails guns]
RobertL
January 16, 2020, 11:51:51 PM
post Re: Next Gen DRSSTC
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Netzpfuscher
January 16, 2020, 11:59:04 AM
post Re: Easy Oscillator for Induction Heating and, Maybe Tesla Coil Power?
[Electronic Circuits]
T3sl4co1l
January 16, 2020, 02:53:32 AM
post Re: Next Gen DRSSTC
[Dual Resonant Solid State Tesla coils (DRSSTC)]
acobaugh
January 15, 2020, 08:57:37 PM
post Re: Universal bus precharge & fan speed controller
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Mads Barnkob
January 15, 2020, 07:27:10 PM
post Re: Universal bus precharge & fan speed controller
[Dual Resonant Solid State Tesla coils (DRSSTC)]
acobaugh
January 15, 2020, 07:08:00 PM
post Re: Easy Oscillator for Induction Heating and, Maybe Tesla Coil Power?
[Electronic Circuits]
Mads Barnkob
January 15, 2020, 01:26:57 PM
post Re: Commercial circuit simulator Micro-Cap 12 is now free to download
[Laboratories, Equipment and Tools]
SteveN87
January 15, 2020, 12:37:28 PM
post Re: Commercial circuit simulator Micro-Cap 12 is now free to download
[Laboratories, Equipment and Tools]
Twospoons
January 15, 2020, 01:15:45 AM
post Easy Oscillator for Induction Heating and, Maybe Tesla Coil Power?
[Electronic Circuits]
petespaco
January 14, 2020, 11:19:23 PM
post Re: Welcome new members, come say hello and tell a little about yourself :)
[General Chat]
Nicko
January 14, 2020, 10:50:54 PM
post Ebay [US] 1x CM300HA-24H H-series, 20$ for a single switch brick
[Sell / Buy / Trade]
Mads Barnkob
January 14, 2020, 08:24:10 PM
post Re: Mazilli ZVS Driver Modification Problems
[Transformer (Ferrite Core)]
T3sl4co1l
January 14, 2020, 07:36:14 PM
post Re: Commercial circuit simulator Micro-Cap 12 is now free to download
[Laboratories, Equipment and Tools]
shrad
January 14, 2020, 12:51:32 PM
post Re: Mazilli ZVS Driver Modification Problems
[Transformer (Ferrite Core)]
davekni
January 14, 2020, 05:27:11 AM
post Re: Mazilli ZVS Driver Modification Problems
[Transformer (Ferrite Core)]
Andrew321
January 14, 2020, 02:27:54 AM
post Re: Ok now I'm stuck ¯\_(ツ)_/¯
[Dual Resonant Solid State Tesla coils (DRSSTC)]
dj.cosmo.esq
January 13, 2020, 11:42:07 PM
post Commercial circuit simulator Micro-Cap 12 is now free to download
[Laboratories, Equipment and Tools]
Mads Barnkob
January 13, 2020, 11:30:11 PM

Sitemap 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 
SimplePortal 2.3.6 © 2008-2014, SimplePortal