Author Topic: Flyback secondary burnout  (Read 517 times)

Offline abstruse1

  • High Voltage Experimenter
  • **
  • Posts: 93
  • Karma: +0/-0
    • View Profile
Flyback secondary burnout
« on: August 02, 2021, 05:47:02 PM »
I've toasted a few old TV flybacks.  I read recently that they shouldn't be run with an open (infinite resistance) secondary because the voltage gets too high for the insulation.  Is this generally true?

One could put a short spark gap or a high voltage resistor across the secondary output.  The resistor might be preferable, except that it would be a drag on the output voltage all the time, not just when a spark gap was sparking.  What does anyone suggest?  If I used a HV resistor, roughly what resistance?  I have several 240k and up from there.

Another idea would be to use a MOT instead of a flyback. Maybe two MOTs could be run in series to get enough voltage?

Than, guys.
Abstruse1
   Been working with electricity for 60 years and still getting a tingle!

Offline johnnyzoo

  • High Voltage Enthusiast
  • *
  • Posts: 30
  • Karma: +2/-0
    • View Profile
Re: Flyback secondary burnout
« Reply #1 on: August 03, 2021, 06:31:34 PM »
I've toasted a few old TV flybacks.  I read recently that they shouldn't be run with an open (infinite resistance) secondary because the voltage gets too high for the insulation.  Is this generally true?

One could put a short spark gap or a high voltage resistor across the secondary output.  The resistor might be preferable, except that it would be a drag on the output voltage all the time, not just when a spark gap was sparking.  What does anyone suggest?  If I used a HV resistor, roughly what resistance?  I have several 240k and up from there.

Another idea would be to use a MOT instead of a flyback. Maybe two MOTs could be run in series to get enough voltage?

Than, guys.

I'm not sure about TV/CRT transformers specifically, but in general, it is true that transformers operated in a flyback type of converter (1) or in certain resonant converters may be damaged if they are operated without load.

Which is better, spark gap or resistor, depends on your application. A resistor will dissipate some power all the time. A spark gap will only fire when the voltage gets high enough, but then it will appear almost like a short circuit.


Whether using microwave oven transformers is a good solution also depends on your application. Using them in series is not impossible but it requires great care. Note that the other end of the high voltage winding is usually connected to the transformer chassis. The frequency is low compared to flybacks (50 Hz vs some ... tens of kHz) and you will get around 2 kV from one microwave oven transformer. And perhaps most importantly, a microwave oven transformer can produce a deadly amount of current at a very dangerous frequency if you get a shock from it. TV/CRT flyback transformers are safer, although you should always avoid getting a shock. Maintain distance, use insulated stick, stands etc, and keep your work area clean.



1) Storing energy in the magnetic field and releasing it; TV transformers are operated this way in their normal application. Basic mechanical and transistor-based ignition coil circuits also work this way. But not all "flyback drivers" used by hobbyists operate in flyback mode - some of them may operate like ordinary transformers, others may be resonant.
« Last Edit: August 03, 2021, 07:25:30 PM by johnnyzoo »

Offline Mat

  • High Voltage Enthusiast
  • *
  • Posts: 1
  • Karma: +0/-0
    • View Profile
Re: Flyback secondary burnout
« Reply #2 on: April 28, 2022, 11:13:48 AM »
I've toasted a few also, these days that im doing experiments with one of these chinese ZVS driver. I'm not very good at theory, so maybe there are mistakes in what ill say. Please forgive me and correct me if its the case (and also, any advice on how to care better for flybacks is welcome!). So, according to what ive seen, I'd say its more amp-related than volt-related (with these chinese ZVS and regular TV flyback).
through my lots of tests i have been having often open-circuit voltage (when the gap is to big for making the arc) sometime for a whole minute. Zero amps, zero problem, the flyback kept alive. But as soon as i'd be running the flyback with a jakob ladder doing continuous sparks between 5-10A (measured before the ZVS) i have to cool down the flyback with a fan, use a duty cycle of 20%, never more than 2 minutes, and the flyback gets very hot and burns often.
I guess there is a current limiting inductor in the ZVS design that protects the flyback in case of open-circuit.
« Last Edit: April 28, 2022, 11:35:52 AM by Mat »

Offline klugesmith

  • High Voltage Engineer
  • ****
  • Posts: 472
  • Karma: +16/-0
    • View Profile
Re: Flyback secondary burnout
« Reply #3 on: April 29, 2022, 05:55:43 PM »
Pay attention to where Johnny said
>>1) Storing energy in the magnetic field and releasing it; TV transformers are operated this way in their normal application. Basic mechanical and transistor-based ignition coil circuits also work this way.

Whether it's a flyback converter or a spark ignition circuit: Ever think about the unloaded output voltage?
Primary-secondary voltage ratio always applies, during charge and discharge phases. (Both voltages proportional to dFlux/dt.  We might write dPh/dt if we don't want to get the Greek letter with F sound.)

If primary current were interrupted by a perfect switch, and there were no capacitance to receive the stored energy, voltages in the "collapsing field" phase would be determined by breakdown somewhere in primary or secondary circuit.
« Last Edit: April 29, 2022, 10:34:09 PM by klugesmith »

High Voltage Forum

Re: Flyback secondary burnout
« Reply #3 on: April 29, 2022, 05:55:43 PM »

 


* Recent Topics and Posts

post Hamilton drills model1206
[Induction Launchers, Coil Guns and Rails guns]
Range4Harry
May 16, 2022, 11:25:14 PM
post Re: Driving the primary with other than 60Hz
[Spark Gap Tesla Coils (SGTC)]
Robert3z
May 16, 2022, 02:21:11 PM
post Re: ZVS driver based DRSSTC with pictures and details - Student project
[Dual Resonant Solid State Tesla coils (DRSSTC)]
CwhyteKGMS
May 16, 2022, 07:29:15 AM
post Re: ZVS driver based DRSSTC with pictures and details - Student project
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
May 16, 2022, 04:53:18 AM
post Re: Driving the primary with other than 60Hz
[Spark Gap Tesla Coils (SGTC)]
davekni
May 16, 2022, 04:36:44 AM
post ZVS driver based DRSSTC with pictures and details - Student project
[Dual Resonant Solid State Tesla coils (DRSSTC)]
CwhyteKGMS
May 16, 2022, 03:53:48 AM
post Re: Driving the primary with other than 60Hz
[Spark Gap Tesla Coils (SGTC)]
Robert3z
May 16, 2022, 02:20:58 AM
post Re: Problem with SSTC
[Solid State Tesla Coils (SSTC)]
davekni
May 15, 2022, 11:59:37 PM
post Re: Problem with SSTC
[Solid State Tesla Coils (SSTC)]
Nunu00
May 15, 2022, 11:08:49 PM
post Re: Problem with SSTC
[Solid State Tesla Coils (SSTC)]
davekni
May 15, 2022, 09:43:07 PM
post Re: Kaizer DRSSTC 3
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Mads Barnkob
May 15, 2022, 08:22:11 PM
post Re: Problem with SSTC
[Solid State Tesla Coils (SSTC)]
Nunu00
May 15, 2022, 08:03:13 PM
post Re: Problem with SSTC
[Solid State Tesla Coils (SSTC)]
davekni
May 15, 2022, 07:49:51 PM
post Re: Problem with SSTC
[Solid State Tesla Coils (SSTC)]
Nunu00
May 15, 2022, 06:58:45 PM
post Re: Problem with SSTC
[Solid State Tesla Coils (SSTC)]
davekni
May 15, 2022, 06:47:53 PM
post Re: Kaizer DRSSTC 3
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Hydron
May 15, 2022, 04:13:02 PM
post Re: Problem with SSTC
[Solid State Tesla Coils (SSTC)]
Nunu00
May 15, 2022, 02:38:18 PM
post Re: Kaizer DRSSTC 3
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
May 15, 2022, 03:53:35 AM
post Bipolar CW
[Voltage Multipliers]
abstruse1
May 15, 2022, 03:46:25 AM
post Re: Problem with SSTC
[Solid State Tesla Coils (SSTC)]
davekni
May 15, 2022, 03:40:42 AM
post Re: Home made Wimshurst machine and Van De Graaf generator
[Static Electricity]
davekni
May 15, 2022, 02:06:53 AM
post Re: Home made Wimshurst machine and Van De Graaf generator
[Static Electricity]
haversin
May 14, 2022, 10:26:32 PM
post Re: Problem with SSTC
[Solid State Tesla Coils (SSTC)]
Nunu00
May 14, 2022, 09:52:06 PM
post Re: Problem with SSTC
[Solid State Tesla Coils (SSTC)]
davekni
May 14, 2022, 09:25:23 PM
post Re: Problem with SSTC
[Solid State Tesla Coils (SSTC)]
Nunu00
May 14, 2022, 08:14:38 PM
post Re: Problem with SSTC
[Solid State Tesla Coils (SSTC)]
davekni
May 14, 2022, 08:02:22 PM
post Re: Flanging sound coming from DRSSTC
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Coileone
May 14, 2022, 06:15:59 PM
post Re: Flanging sound coming from DRSSTC
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Coileone
May 14, 2022, 06:12:32 PM
post Problem with SSTC
[Solid State Tesla Coils (SSTC)]
Nunu00
May 14, 2022, 05:18:16 PM
post Re: Wago "Lever Nuts"?
[General Chat]
Mads Barnkob
May 14, 2022, 03:24:48 PM
post Re: Flanging sound coming from DRSSTC
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
May 13, 2022, 11:06:50 PM
post Re: Flanging sound coming from DRSSTC
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Mads Barnkob
May 13, 2022, 09:28:35 PM
post Re: Kaizer DRSSTC 3
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Mads Barnkob
May 13, 2022, 09:24:22 PM
post Re: Flanging sound coming from DRSSTC
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Coileone
May 13, 2022, 02:13:19 PM
post Re: Flanging sound coming from DRSSTC
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Coileone
May 13, 2022, 02:09:23 PM
post Re: Flanging sound coming from DRSSTC
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
May 13, 2022, 06:16:20 AM
post Re: Flanging sound coming from DRSSTC
[Dual Resonant Solid State Tesla coils (DRSSTC)]
klugesmith
May 13, 2022, 01:57:25 AM
post Flanging sound coming from DRSSTC
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Coileone
May 12, 2022, 10:05:32 PM
post Re: 3 Phase 400 VAC 6 A Variac Stack With Voltage/Current Meters
[Transformer (Iron Core)]
rikkitikkitavi
May 12, 2022, 09:41:04 PM
post Re: Thermometers
[Laboratories, Equipment and Tools]
rikkitikkitavi
May 12, 2022, 09:33:38 PM
post Re: Wago "Lever Nuts"?
[General Chat]
rikkitikkitavi
May 12, 2022, 09:27:40 PM
post Re: Driving the primary with other than 60Hz
[Spark Gap Tesla Coils (SGTC)]
Robert3z
May 12, 2022, 02:13:03 PM
post Re: Hi frequency ringing with GDT
[Solid State Tesla Coils (SSTC)]
davekni
May 12, 2022, 06:39:55 AM
post Re: Home made Wimshurst machine and Van De Graaf generator
[Static Electricity]
davekni
May 12, 2022, 06:27:47 AM
post Re: Driving the primary with other than 60Hz
[Spark Gap Tesla Coils (SGTC)]
davekni
May 12, 2022, 06:22:48 AM
post Wago "Lever Nuts"?
[General Chat]
abstruse1
May 12, 2022, 04:32:19 AM
post Re: Transistor choice
[Dual Resonant Solid State Tesla coils (DRSSTC)]
flyingperson23
May 12, 2022, 03:32:22 AM
post Re: Thermometers
[Laboratories, Equipment and Tools]
Twospoons
May 12, 2022, 12:00:11 AM
post Re: Kaizer DRSSTC 3
[Dual Resonant Solid State Tesla coils (DRSSTC)]
klugesmith
May 11, 2022, 09:53:15 PM
post Kaizer DRSSTC 3
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Mads Barnkob
May 11, 2022, 09:40:00 PM
post Re: Hi frequency ringing with GDT
[Solid State Tesla Coils (SSTC)]
CarldeLevis
May 11, 2022, 09:39:21 PM
post Thermometers
[Laboratories, Equipment and Tools]
klugesmith
May 11, 2022, 09:36:59 PM
post Re: Home made Wimshurst machine and Van De Graaf generator
[Static Electricity]
Nicolas
May 11, 2022, 09:29:45 PM
post Re: Litz Wire?
[General Chat]
Mads Barnkob
May 11, 2022, 08:45:57 PM
post Re: Hi frequency ringing with GDT
[Solid State Tesla Coils (SSTC)]
Mads Barnkob
May 11, 2022, 08:43:38 PM
post Hi frequency ringing with GDT
[Solid State Tesla Coils (SSTC)]
CarldeLevis
May 11, 2022, 05:44:40 PM
post Re: Driving the primary with other than 60Hz
[Spark Gap Tesla Coils (SGTC)]
Hydron
May 11, 2022, 04:17:34 PM
post Re: Driving the primary with other than 60Hz
[Spark Gap Tesla Coils (SGTC)]
Robert3z
May 11, 2022, 03:10:27 PM
post Re: Driving the primary with other than 60Hz
[Spark Gap Tesla Coils (SGTC)]
Hydron
May 11, 2022, 01:46:57 PM
post Re: Driving the primary with other than 60Hz
[Spark Gap Tesla Coils (SGTC)]
Robert3z
May 11, 2022, 12:37:19 PM
post Re: Home made Wimshurst machine and Van De Graaf generator
[Static Electricity]
Uspring
May 11, 2022, 11:33:30 AM
post Re: Driving the primary with other than 60Hz
[Spark Gap Tesla Coils (SGTC)]
Hydron
May 11, 2022, 11:00:59 AM
post Re: Driving the primary with other than 60Hz
[Spark Gap Tesla Coils (SGTC)]
davekni
May 11, 2022, 06:30:45 AM
post Re: Home made Wimshurst machine and Van De Graaf generator
[Static Electricity]
davekni
May 11, 2022, 06:11:08 AM
post Re: Litz Wire?
[General Chat]
abstruse1
May 11, 2022, 04:00:41 AM
post Driving the primary with other than 60Hz
[Spark Gap Tesla Coils (SGTC)]
Robert3z
May 11, 2022, 02:06:34 AM
post Re: Home made Wimshurst machine and Van De Graaf generator
[Static Electricity]
Mads Barnkob
May 10, 2022, 07:52:45 PM
post Re: Home made Wimshurst machine and Van De Graaf generator
[Static Electricity]
Nicolas
May 10, 2022, 10:04:27 AM
post Re: Transistor choice
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Mads Barnkob
May 10, 2022, 09:31:39 AM
post Re: Litz Wire?
[General Chat]
Mads Barnkob
May 10, 2022, 09:29:19 AM
post Re: Welcome new members, come say hello and tell a little about yourself :)
[General Chat]
Mads Barnkob
May 10, 2022, 09:23:38 AM
post Re: Transistor choice
[Dual Resonant Solid State Tesla coils (DRSSTC)]
AstRii
May 10, 2022, 07:24:33 AM
post Transistor choice
[Dual Resonant Solid State Tesla coils (DRSSTC)]
flyingperson23
May 10, 2022, 03:33:10 AM
post Litz Wire?
[General Chat]
abstruse1
May 10, 2022, 03:16:29 AM
post Re: Home made Wimshurst machine and Van De Graaf generator
[Static Electricity]
DashApple
May 09, 2022, 07:41:51 AM
post Re: Home made Wimshurst machine and Van De Graaf generator
[Static Electricity]
johnf
May 09, 2022, 05:39:51 AM
post Re: Home made Wimshurst machine and Van De Graaf generator
[Static Electricity]
davekni
May 09, 2022, 12:44:13 AM
post Re: First tesla coil building / Questions before ignition
[Spark Gap Tesla Coils (SGTC)]
Nicolas
May 09, 2022, 12:24:37 AM
post Home made Wimshurst machine and Van De Graaf generator
[Static Electricity]
Nicolas
May 09, 2022, 12:21:40 AM
post Ground, Grounding, Grounded?
[General Chat]
abstruse1
May 09, 2022, 12:13:01 AM
post Re: QCW questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
May 08, 2022, 06:43:31 PM
post Re: QCW questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Rafft
May 08, 2022, 07:43:13 AM
post Re: 3 Phase 400 VAC 6 A Variac Stack With Voltage/Current Meters
[Transformer (Iron Core)]
Mads Barnkob
May 07, 2022, 07:59:36 PM
post Re: Welcome new members, come say hello and tell a little about yourself :)
[General Chat]
Robert3z
May 07, 2022, 06:41:41 PM
post Re: Capacitor Esoterica
[General Chat]
abstruse1
May 07, 2022, 05:57:22 PM
post Re: 3 Phase 400 VAC 6 A Variac Stack With Voltage/Current Meters
[Transformer (Iron Core)]
Hydron
May 07, 2022, 03:43:57 PM
post 3 Phase 400 VAC 6 A Variac Stack With Voltage/Current Meters
[Transformer (Iron Core)]
Mads Barnkob
May 07, 2022, 03:21:16 PM
post Re: QCW questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Rafft
May 07, 2022, 06:52:29 AM
post Re: QCW questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
May 07, 2022, 04:57:41 AM
post Re: QCW questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Rafft
May 06, 2022, 08:54:52 AM
post Re: QCW questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
May 06, 2022, 02:54:44 AM
post Re: DRSSTC No Breakout On Topload
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Dhaygoh
May 05, 2022, 05:26:27 PM
post Re: DRSSTC No Breakout On Topload
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Dhaygoh
May 05, 2022, 05:14:32 PM
post Re: QCW questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Rafft
May 05, 2022, 06:29:00 AM
post Re: QCW questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
May 05, 2022, 05:56:01 AM
post Re: QCW questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Rafft
May 05, 2022, 05:11:45 AM
post Re: QCW questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
May 05, 2022, 04:37:42 AM
post Re: DRSSTC No Breakout On Topload
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
May 05, 2022, 04:19:47 AM
post Re: Capacitor Esoterica
[General Chat]
johnf
May 04, 2022, 11:22:09 PM
post Re: DRSSTC driver in the chip shortage
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Hydron
May 04, 2022, 11:04:19 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