Author Topic: MC34063 based Nixie tube power supply oscillations  (Read 3956 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 Senior
  • *****
  • Posts: 851
  • Karma: +7/-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 Enthusiast
  • *
  • Posts: 34
  • Karma: +3/-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 Senior
  • *****
  • Posts: 851
  • Karma: +7/-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 Re: My First DRSSTC
[Dual Resonant Solid State Tesla coils]
sjsimmo
Today at 08:08:58 AM
post Re: How to calculate VA rating and other things for Ferrite Core? (SMPS)
[Transformer (ferrite core)]
sjsimmo
Today at 01:24:15 AM
post How to calculate VA rating and other things for Ferrite Core? (SMPS)
[Transformer (ferrite core)]
FilipŠebík
January 18, 2019, 07:32:38 PM
post Re: How to design a 7.5kV AC source?
[Transformer (ferrite core)]
profdc9
January 18, 2019, 04:25:14 PM
post How to design a 7.5kV AC source?
[Transformer (ferrite core)]
CristianM
January 18, 2019, 03:48:06 PM
post Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
[Electronic circuits]
the_anomaly
January 17, 2019, 02:01:36 AM
post Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
[Electronic circuits]
petespaco
January 16, 2019, 04:26:38 AM
post AC vs DC fuses, high current, explosive destructive testing and theory
[Capacitor banks]
Mads Barnkob
January 15, 2019, 09:48:48 PM
post Re: My X-Ray Machine
[X-ray]
neukyhm
January 15, 2019, 10:51:46 AM
post Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
[Electronic circuits]
petespaco
January 14, 2019, 05:08:38 PM
post Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
[Electronic circuits]
the_anomaly
January 14, 2019, 01:15:53 PM
post Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
[Electronic circuits]
Mads Barnkob
January 14, 2019, 12:22:07 PM
post Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
[Electronic circuits]
petespaco
January 11, 2019, 05:10:39 AM
post Re: My X-Ray Machine
[X-ray]
Max
January 10, 2019, 10:59:25 PM
post Re: 迎词、来
[General chatting]
profdc9
January 10, 2019, 06:56:59 PM
post Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
[Electronic circuits]
petespaco
January 10, 2019, 05:33:48 PM
post Re: Welcome new members, come say hello and tell a little about yourself :)
[General chatting]
black.yang
January 10, 2019, 02:11:58 AM
post Re: My X-Ray Machine
[X-ray]
Mads Barnkob
January 09, 2019, 09:14:59 PM
post Acoustic spectra of sung vowels by the FFT analyzer HP 3561A
[Electronic circuits]
Physikfan
January 08, 2019, 08:44:16 PM
post Re: IGBT failure in DRSSTC
[Dual Resonant Solid State Tesla coils]
Felix Bieri
January 08, 2019, 05:33:55 PM
post Re: Huawei RRU3928 1800MHz radio base station teardown (part 1 of 2)
[Radio frequency]
Mads Barnkob
January 08, 2019, 08:25:08 AM
post Re: SimpleDriver v2.3, my phase-shifting QCW DRSSTC controller
[Dual Resonant Solid State Tesla coils]
flyglas
January 08, 2019, 08:25:02 AM
post Re: SimpleDriver v2.3, my phase-shifting QCW DRSSTC controller
[Dual Resonant Solid State Tesla coils]
Hydron
January 08, 2019, 02:01:50 AM
post Re: (DR)SSTC II
[Dual Resonant Solid State Tesla coils]
Hydron
January 07, 2019, 10:23:38 PM
post Re: (DR)SSTC II
[Dual Resonant Solid State Tesla coils]
Laci
January 07, 2019, 08:53:32 PM
post Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
[Electronic circuits]
petespaco
January 07, 2019, 08:17:44 PM
post Re: SimpleDriver v2.3, my phase-shifting QCW DRSSTC controller
[Dual Resonant Solid State Tesla coils]
Netzpfuscher
January 07, 2019, 07:37:53 PM
post Re: (DR)SSTC II
[Dual Resonant Solid State Tesla coils]
Uspring
January 07, 2019, 01:30:36 PM
post Re: (DR)SSTC II
[Dual Resonant Solid State Tesla coils]
Laci
January 07, 2019, 12:43:26 PM
post Re: (DR)SSTC II
[Dual Resonant Solid State Tesla coils]
Hydron
January 07, 2019, 08:09:49 AM
post Re: SimpleDriver v2.3, my phase-shifting QCW DRSSTC controller
[Dual Resonant Solid State Tesla coils]
NEYi
January 07, 2019, 07:43:50 AM
post Re: Welcome new members, come say hello and tell a little about yourself :)
[General chatting]
Mads Barnkob
January 07, 2019, 06:48:06 AM
post Re: (DR)SSTC II
[Dual Resonant Solid State Tesla coils]
Mads Barnkob
January 07, 2019, 06:39:56 AM
post Re: (DR)SSTC II
[Dual Resonant Solid State Tesla coils]
Laci
January 06, 2019, 09:23:19 PM
post Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
[Electronic circuits]
petespaco
January 06, 2019, 07:11:25 PM
post Re: (DR)SSTC II
[Dual Resonant Solid State Tesla coils]
Uspring
January 06, 2019, 07:02:14 PM
post Re: (DR)SSTC II
[Dual Resonant Solid State Tesla coils]
flyglas
January 06, 2019, 12:43:46 PM
post Re: (DR)SSTC II
[Dual Resonant Solid State Tesla coils]
Laci
January 06, 2019, 11:55:09 AM
post Re: (DR)SSTC II
[Dual Resonant Solid State Tesla coils]
TDAF
January 06, 2019, 09:48:06 AM
post Re: First SSTC build, need help troubleshooting
[Solid state Tesla coils]
TDAF
January 06, 2019, 09:45:17 AM
post 关于: 这个便宜的 drsstc 驱动程序从 aliexpress 1.3 b 类型?
[Dual Resonant Solid State Tesla coils]
black.yang
January 06, 2019, 08:34:46 AM
post 迎词、来
[General chatting]
black.yang
January 06, 2019, 08:20:21 AM
post Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
[Electronic circuits]
flyrod
January 06, 2019, 12:34:15 AM
post Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
[Electronic circuits]
petespaco
January 05, 2019, 05:27:23 PM
post Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
[Electronic circuits]
flyrod
January 05, 2019, 03:46:29 PM
post Re: (DR)SSTC II
[Dual Resonant Solid State Tesla coils]
Laci
January 05, 2019, 09:51:10 AM
post Re: (DR)SSTC II
[Dual Resonant Solid State Tesla coils]
Mads Barnkob
January 04, 2019, 11:02:25 PM
post Re: (DR)SSTC II
[Dual Resonant Solid State Tesla coils]
Laci
January 03, 2019, 08:38:15 PM
post Re: SimpleDriver v2.3, my phase-shifting QCW DRSSTC controller
[Dual Resonant Solid State Tesla coils]
flyglas
January 03, 2019, 08:15:48 PM
post Re: Component questions
[Dual Resonant Solid State Tesla coils]
Mads Barnkob
January 03, 2019, 02:05:31 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