On Thursday, 15 June 2023 at 21:35:40 UTC+1, Lamont Cranston wrote:
> On Thursday, June 15, 2023 at 3:32:29 PM UTC-5, Tabby wrote:
>
> > > I sent a question about the output to the seller, they forwarded it on to the manufacturer.
> > totally pointless
> What is pointless? Asking for more info, or expecting to get it?
> Mikek
asking a liar in writing whether they're lying
Reply by Anthony William Sloman●June 19, 20232023-06-19
On Monday, June 19, 2023 at 2:44:44 AM UTC+10, Lamont Cranston wrote:
> > It's just a blocking oscillator modified for regulation.
> I'm assuming this is in response the the circuit at the center tap of the secondary.
> So far my experience with 60 Hz neon sign transformers is that the inductance of the secondary
> limits the current to 30ma, and they have no other regulation.
> With this switching style running at 20kHz, would lead me to believe that impedance limiting is
> even more likely to happen.The series secondaries measure 10H, which is 1.257MΩ at 20kHz.
> 7.4kV / 1.257MΩ equals 6ma. That seems low in my somewhat limited experience, but I have 8 or 10 neon sign transformers
> and all have 30ma impedance limited output current.
> So, that 6ma is a bit confusing.
In transformers, the induced current by-passes the inductance. A current flowing through the primary that is cancelled by a matching (same number of ampere turns) current in the secondaries doesn't generate any back EMF so it isn't limited by the inductance of any of the coils.
The fact that the primary-secondary couplng isn't perfect does impose an upper limit in practice but a couple of 0.99 or better isn't unknown.
http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/tracir.html
That link does give the transformer equation, but doesn't bother with M=k .Sqr-root(L1.L2) where k is the coupling coefficient which can be anywhere from 0 to almost one. 0.99 to 0.999 is pretty typical.
--
Bill Sloman, Sydney
Reply by Lamont Cranston●June 18, 20232023-06-18
> It's just a blocking oscillator modified for regulation.
I'm assuming this is in response the the circuit at the center tap of the secondary.
So far my experience with 60 Hz neon sign transformers is that the inductance of the secondary
limits the current to 30ma, and they have no other regulation.
With this switching style running at 20kHz, would lead me to believe that impedance limiting is
even more likely to happen.The series secondaries measure 10H, which is 1.257MΩ at 20kHz.
7.4kV / 1.257MΩ equals 6ma. That seems low in my somewhat limited experience, but I have 8 or 10 neon sign transformers
and all have 30ma impedance limited output current.
So, that 6ma is a bit confusing.
Thanks, Mikek
Reply by Lamont Cranston●June 18, 20232023-06-18
> > Has this Center Tap circuit stumped everyone?
> > Mikek
> Are you sure those "SCRs" aren't triacs?
> Ed
It's just a blocking oscillator modified for regulation.
Reply by ehsjr●June 18, 20232023-06-18
On 6/18/2023 10:56 AM, Lamont Cranston wrote:
> On Saturday, June 17, 2023 at 1:04:33 AM UTC-5, Lamont Cranston wrote:
>> On Tuesday, June 13, 2023 at 7:40:39 PM UTC-5, Lamont Cranston wrote:
>>> On Tuesday, June 13, 2023 at 1:38:10 PM UTC-5, Tauno Voipio wrote:
>>>> On 13.6.2023 20.57, Lamont Cranston wrote:
>>>>> On Tuesday, June 13, 2023 at 12:04:38 PM UTC-5, John Larkin wrote:
>>>>>> On Tue, 13 Jun 2023 09:22:20 -0700 (PDT), Lamont Cranston
>>>>>> <amd...@gmail.com> wrote:
>>>>>>
>>>>>>> I'm backing off of the neon sign transformer 12kV power supply. For the reasons I was told, the low frequency requires big capacitors. Also, I ordered 20kV caps from Amazon and 6 of the 12 failed at under 4kV. I should have read the reviews, it is well shown these fail.
>>>>>>> So, I want a continuous DC voltage, I can imagine the old tripler design gave a decent continuous DC, but I'm looking at this and wondering what kind of DC they have. https://www.ebay.com/itm/185000537079?var=692782023047
>>>>>>> I don't see a tripler, I don't see any diodes or filter caps, I'm hesitant to spend the fifty bucks to find it isn't what I need.
>>>>>>> Any thoughts about this?
>>>>>>> Thanks, Mikek
>>>>>> Some color TVs had a potted flyback-rectifier thing.
>>>>>>
>>>>>> https://www.ebay.com/itm/266268712401?hash=item3dfeda1dd1:g:ZjUAAOSwMtJjVfKj&amdata=enc%3AAQAIAAAA4FkSVq2pZQAQFQ3H12RU5oBxz034DQjMgNb0SpovprqoAC9lmUILzo7UQOD6mORpnWwDWDkzPWIUtDhR40PoeddhTnTcHOIMviQ7J%2B4TKb4EENkJXKDXyP5N99Q5SDpcmLbn%2B52pNUnNG7D9wMmK8DJG1Ipa2UaBiWpAlOGLbl80axK%2BKmL9Cua77cwAJmfwF39%2FXC%2BP4BUGfJCc6I2ejKGqduU1xpDuLmVnOmw05c9rl8Rj6JOH2YLiOv%2BedgBO2I5zzWYjSwZKdXGomfJo1hNa6CQHPd22X9mybYVrJ2%2Bk%7Ctkp%3ABFBM1ICr25Zi
>>>>>
>>>>> Any idea what the duty cycle of the input was on the TV flybacks?
>>>>> Mikek
>>>> For CCIR type G analog raster (625 line, 50 half-frames / second), the
>>>> trace time was about 53 us and retrace 11 us, for a sum of 64 us.
>>>>
>>>> --
>>>>
>>>> -TV
>>> I have a couple of defective High frequency switching type neon sign power supplies.
>>> Neither work and seem to have open secondaries. I removed the switching pcb and found
>>> defective IRF 630 FETs, I replaced them and got it switching, but no HV. So, of course I stuck
>>> the transformer in the barbecue and melted off all the tar, and a little kerosene and it was free.
>>> https://www.dropbox.com/s/xsc1f0edqc0w3jk/Neon%20switching%20supply%20transformer%202.jpg?dl=0
>>> But, I was surprised to see a pcb encased in the tar, that connects the two secondary windings
>>> at the CT. It has a 555 a couple of SCRs and caps a diodes to make a power supply for the 555.
>>> I'm not sure of the purpose of this pcb, it would seem like current limiting, but this runs at 21kHz,
>>> I would think secondary impedance would be enough to limit current.
>>> Any thought as to what the pcb connecting the two secondary windings together would be doing?
>>> https://www.dropbox.com/s/4c4he4esxxtjn7y/Neon%20switching%20supply%20CT%20pcb.jpg?dl=0
>>> Mikek
>> I drew the schematic of the tar potted pcb that is connected between the two halves of the secondary. I'd like opinions on what the function
>> of the pcb is. It has a 555 driving two SCRs. The transformer already has a driver circuit on the primary.
>> What is the function of this circuit on the secondary.
>>
>> https://www.dropbox.com/s/jkl62gxr6omhxib/Switching%20Power%20Supply%20CT%20%20PCB.jpg?dl=0
>>
>> Picture of pcb,
>> https://www.dropbox.com/s/4c4he4esxxtjn7y/Neon%20switching%20supply%20CT%20pcb.jpg?dl=0
>> Thanks, Mikek
>
> Has this Center Tap circuit stumped everyone?
> Mikek
Are you sure those "SCRs" aren't triacs?
Ed
Reply by Anthony William Sloman●June 18, 20232023-06-18
On Monday, June 19, 2023 at 12:56:10 AM UTC+10, Lamont Cranston wrote:
> On Saturday, June 17, 2023 at 1:04:33 AM UTC-5, Lamont Cranston wrote:
> > On Tuesday, June 13, 2023 at 7:40:39 PM UTC-5, Lamont Cranston wrote:
> > > On Tuesday, June 13, 2023 at 1:38:10 PM UTC-5, Tauno Voipio wrote:
> > > > On 13.6.2023 20.57, Lamont Cranston wrote:
> > > > > On Tuesday, June 13, 2023 at 12:04:38 PM UTC-5, John Larkin wrote:
> > > > >> On Tue, 13 Jun 2023 09:22:20 -0700 (PDT), Lamont Cranston
> > > > >> <amd...@gmail.com> wrote:
> > > > >>
> > > > >>> I'm backing off of the neon sign transformer 12kV power supply. For the reasons I was told, the low frequency requires big capacitors. Also, I ordered 20kV caps from Amazon and 6 of the 12 failed at under 4kV. I should have read the reviews, it is well shown these fail.
> > > > >>> So, I want a continuous DC voltage, I can imagine the old tripler design gave a decent continuous DC, but I'm looking at this and wondering what kind of DC they have. https://www.ebay.com/itm/185000537079?var=692782023047
> > > > >>> I don't see a tripler, I don't see any diodes or filter caps, I'm hesitant to spend the fifty bucks to find it isn't what I need.
> > > > >>> Any thoughts about this?
> > > > >>> Thanks, Mikek
> > > > >> Some color TVs had a potted flyback-rectifier thing.
> > > > >>
> > > > >> https://www.ebay.com/itm/266268712401?hash=item3dfeda1dd1:g:ZjUAAOSwMtJjVfKj&amdata=enc%3AAQAIAAAA4FkSVq2pZQAQFQ3H12RU5oBxz034DQjMgNb0SpovprqoAC9lmUILzo7UQOD6mORpnWwDWDkzPWIUtDhR40PoeddhTnTcHOIMviQ7J%2B4TKb4EENkJXKDXyP5N99Q5SDpcmLbn%2B52pNUnNG7D9wMmK8DJG1Ipa2UaBiWpAlOGLbl80axK%2BKmL9Cua77cwAJmfwF39%2FXC%2BP4BUGfJCc6I2ejKGqduU1xpDuLmVnOmw05c9rl8Rj6JOH2YLiOv%2BedgBO2I5zzWYjSwZKdXGomfJo1hNa6CQHPd22X9mybYVrJ2%2Bk%7Ctkp%3ABFBM1ICr25Zi
> > > > >
> > > > > Any idea what the duty cycle of the input was on the TV flybacks?
> > > > > Mikek
> > > > For CCIR type G analog raster (625 line, 50 half-frames / second), the
> > > > trace time was about 53 us and retrace 11 us, for a sum of 64 us.
> > > >
> > > > --
> > > >
> > > > -TV
> > > I have a couple of defective High frequency switching type neon sign power supplies.
> > > Neither work and seem to have open secondaries. I removed the switching pcb and found
> > > defective IRF 630 FETs, I replaced them and got it switching, but no HV. So, of course I stuck
> > > the transformer in the barbecue and melted off all the tar, and a little kerosene and it was free.
> > > https://www.dropbox.com/s/xsc1f0edqc0w3jk/Neon%20switching%20supply%20transformer%202.jpg?dl=0
> > > But, I was surprised to see a pcb encased in the tar, that connects the two secondary windings
> > > at the CT. It has a 555 a couple of SCRs and caps a diodes to make a power supply for the 555.
> > > I'm not sure of the purpose of this pcb, it would seem like current limiting, but this runs at 21kHz,
> > > I would think secondary impedance would be enough to limit current.
> > > Any thought as to what the pcb connecting the two secondary windings together would be doing?
> > > https://www.dropbox.com/s/4c4he4esxxtjn7y/Neon%20switching%20supply%20CT%20pcb.jpg?dl=0
> > > Mikek
> > I drew the schematic of the tar potted pcb that is connected between the two halves of the secondary. I'd like opinions on what the function
> > of the pcb is. It has a 555 driving two SCRs. The transformer already has a driver circuit on the primary.
> > What is the function of this circuit on the secondary.
> >
> > https://www.dropbox.com/s/jkl62gxr6omhxib/Switching%20Power%20Supply%20CT%20%20PCB.jpg?dl=0
> >
> > Picture of pcb,
> > https://www.dropbox.com/s/4c4he4esxxtjn7y/Neon%20switching%20supply%20CT%20pcb.jpg?dl=0
>
> Has this Center Tap circuit stumped everyone?
More likely they can't be bothered redrawing it in a way that makes it easy to make sense of what it is doing. Since there's a 555 at the heart of it it's either old or designed by somebody who didn't notice when the 555 went obsolete - like John Fields. The fact that the winding direction of the two secondaries isn't specified - no dots - is bad start.
No turns ratios and no specification of the primary drive makes it difficult to work out what might be going on. I'm not temped to try.
--
Bill Slonman, Sydney
Reply by Lamont Cranston●June 18, 20232023-06-18
On Saturday, June 17, 2023 at 1:04:33 AM UTC-5, Lamont Cranston wrote:
> On Tuesday, June 13, 2023 at 7:40:39 PM UTC-5, Lamont Cranston wrote:
> > On Tuesday, June 13, 2023 at 1:38:10 PM UTC-5, Tauno Voipio wrote:
> > > On 13.6.2023 20.57, Lamont Cranston wrote:
> > > > On Tuesday, June 13, 2023 at 12:04:38 PM UTC-5, John Larkin wrote:
> > > >> On Tue, 13 Jun 2023 09:22:20 -0700 (PDT), Lamont Cranston
> > > >> <amd...@gmail.com> wrote:
> > > >>
> > > >>> I'm backing off of the neon sign transformer 12kV power supply. For the reasons I was told, the low frequency requires big capacitors. Also, I ordered 20kV caps from Amazon and 6 of the 12 failed at under 4kV. I should have read the reviews, it is well shown these fail.
> > > >>> So, I want a continuous DC voltage, I can imagine the old tripler design gave a decent continuous DC, but I'm looking at this and wondering what kind of DC they have. https://www.ebay.com/itm/185000537079?var=692782023047
> > > >>> I don't see a tripler, I don't see any diodes or filter caps, I'm hesitant to spend the fifty bucks to find it isn't what I need.
> > > >>> Any thoughts about this?
> > > >>> Thanks, Mikek
> > > >> Some color TVs had a potted flyback-rectifier thing.
> > > >>
> > > >> https://www.ebay.com/itm/266268712401?hash=item3dfeda1dd1:g:ZjUAAOSwMtJjVfKj&amdata=enc%3AAQAIAAAA4FkSVq2pZQAQFQ3H12RU5oBxz034DQjMgNb0SpovprqoAC9lmUILzo7UQOD6mORpnWwDWDkzPWIUtDhR40PoeddhTnTcHOIMviQ7J%2B4TKb4EENkJXKDXyP5N99Q5SDpcmLbn%2B52pNUnNG7D9wMmK8DJG1Ipa2UaBiWpAlOGLbl80axK%2BKmL9Cua77cwAJmfwF39%2FXC%2BP4BUGfJCc6I2ejKGqduU1xpDuLmVnOmw05c9rl8Rj6JOH2YLiOv%2BedgBO2I5zzWYjSwZKdXGomfJo1hNa6CQHPd22X9mybYVrJ2%2Bk%7Ctkp%3ABFBM1ICr25Zi
> > > >
> > > > Any idea what the duty cycle of the input was on the TV flybacks?
> > > > Mikek
> > > For CCIR type G analog raster (625 line, 50 half-frames / second), the
> > > trace time was about 53 us and retrace 11 us, for a sum of 64 us.
> > >
> > > --
> > >
> > > -TV
> > I have a couple of defective High frequency switching type neon sign power supplies.
> > Neither work and seem to have open secondaries. I removed the switching pcb and found
> > defective IRF 630 FETs, I replaced them and got it switching, but no HV. So, of course I stuck
> > the transformer in the barbecue and melted off all the tar, and a little kerosene and it was free.
> > https://www.dropbox.com/s/xsc1f0edqc0w3jk/Neon%20switching%20supply%20transformer%202.jpg?dl=0
> > But, I was surprised to see a pcb encased in the tar, that connects the two secondary windings
> > at the CT. It has a 555 a couple of SCRs and caps a diodes to make a power supply for the 555.
> > I'm not sure of the purpose of this pcb, it would seem like current limiting, but this runs at 21kHz,
> > I would think secondary impedance would be enough to limit current.
> > Any thought as to what the pcb connecting the two secondary windings together would be doing?
> > https://www.dropbox.com/s/4c4he4esxxtjn7y/Neon%20switching%20supply%20CT%20pcb.jpg?dl=0
> > Mikek
> I drew the schematic of the tar potted pcb that is connected between the two halves of the secondary. I'd like opinions on what the function
> of the pcb is. It has a 555 driving two SCRs. The transformer already has a driver circuit on the primary.
> What is the function of this circuit on the secondary.
>
> https://www.dropbox.com/s/jkl62gxr6omhxib/Switching%20Power%20Supply%20CT%20%20PCB.jpg?dl=0
>
> Picture of pcb,
> https://www.dropbox.com/s/4c4he4esxxtjn7y/Neon%20switching%20supply%20CT%20pcb.jpg?dl=0
> Thanks, Mikek
Has this Center Tap circuit stumped everyone?
Mikek
Reply by Lamont Cranston●June 17, 20232023-06-17
On Tuesday, June 13, 2023 at 7:40:39 PM UTC-5, Lamont Cranston wrote:
> On Tuesday, June 13, 2023 at 1:38:10 PM UTC-5, Tauno Voipio wrote:
> > On 13.6.2023 20.57, Lamont Cranston wrote:
> > > On Tuesday, June 13, 2023 at 12:04:38 PM UTC-5, John Larkin wrote:
> > >> On Tue, 13 Jun 2023 09:22:20 -0700 (PDT), Lamont Cranston
> > >> <amd...@gmail.com> wrote:
> > >>
> > >>> I'm backing off of the neon sign transformer 12kV power supply. For the reasons I was told, the low frequency requires big capacitors. Also, I ordered 20kV caps from Amazon and 6 of the 12 failed at under 4kV. I should have read the reviews, it is well shown these fail.
> > >>> So, I want a continuous DC voltage, I can imagine the old tripler design gave a decent continuous DC, but I'm looking at this and wondering what kind of DC they have. https://www.ebay.com/itm/185000537079?var=692782023047
> > >>> I don't see a tripler, I don't see any diodes or filter caps, I'm hesitant to spend the fifty bucks to find it isn't what I need.
> > >>> Any thoughts about this?
> > >>> Thanks, Mikek
> > >> Some color TVs had a potted flyback-rectifier thing.
> > >>
> > >> https://www.ebay.com/itm/266268712401?hash=item3dfeda1dd1:g:ZjUAAOSwMtJjVfKj&amdata=enc%3AAQAIAAAA4FkSVq2pZQAQFQ3H12RU5oBxz034DQjMgNb0SpovprqoAC9lmUILzo7UQOD6mORpnWwDWDkzPWIUtDhR40PoeddhTnTcHOIMviQ7J%2B4TKb4EENkJXKDXyP5N99Q5SDpcmLbn%2B52pNUnNG7D9wMmK8DJG1Ipa2UaBiWpAlOGLbl80axK%2BKmL9Cua77cwAJmfwF39%2FXC%2BP4BUGfJCc6I2ejKGqduU1xpDuLmVnOmw05c9rl8Rj6JOH2YLiOv%2BedgBO2I5zzWYjSwZKdXGomfJo1hNa6CQHPd22X9mybYVrJ2%2Bk%7Ctkp%3ABFBM1ICr25Zi
> > >
> > > Any idea what the duty cycle of the input was on the TV flybacks?
> > > Mikek
> > For CCIR type G analog raster (625 line, 50 half-frames / second), the
> > trace time was about 53 us and retrace 11 us, for a sum of 64 us.
> >
> > --
> >
> > -TV
> I have a couple of defective High frequency switching type neon sign power supplies.
> Neither work and seem to have open secondaries. I removed the switching pcb and found
> defective IRF 630 FETs, I replaced them and got it switching, but no HV. So, of course I stuck
> the transformer in the barbecue and melted off all the tar, and a little kerosene and it was free.
> https://www.dropbox.com/s/xsc1f0edqc0w3jk/Neon%20switching%20supply%20transformer%202.jpg?dl=0
> But, I was surprised to see a pcb encased in the tar, that connects the two secondary windings
> at the CT. It has a 555 a couple of SCRs and caps a diodes to make a power supply for the 555.
> I'm not sure of the purpose of this pcb, it would seem like current limiting, but this runs at 21kHz,
> I would think secondary impedance would be enough to limit current.
> Any thought as to what the pcb connecting the two secondary windings together would be doing?
> https://www.dropbox.com/s/4c4he4esxxtjn7y/Neon%20switching%20supply%20CT%20pcb.jpg?dl=0
> Mikek
On Thursday, 15 June 2023 at 07:41:43 UTC+1, John Robertson wrote:
> On 2023/06/13 8:06 p.m., Lamont Cranston wrote:
> > On Tuesday, June 13, 2023 at 7:49:53 PM UTC-5, John Robertson wrote:
> >> On 2023/06/13 9:22 a.m., Lamont Cranston wrote:
> >>> I'm backing off of the neon sign transformer 12kV power supply. For the reasons I was told, the low frequency requires big capacitors. Also, I ordered 20kV caps from Amazon and 6 of the 12 failed at under 4kV. I should have read the reviews, it is well shown these fail.
> >>> So, I want a continuous DC voltage, I can imagine the old tripler design gave a decent continuous DC, but I'm looking at this and wondering what kind of DC they have. https://www.ebay.com/itm/185000537079?var=692782023047
> >>> I don't see a tripler, I don't see any diodes or filter caps, I'm hesitant to spend the fifty bucks to find it isn't what I need.
> >>> Any thoughts about this?
> >>> Thanks, Mikek
> >>>
> >> What sort of HV are you after and what are the current requirements?
> >>
> >> A Neon sign transformer will give you milliamps at the rated output
> >> voltage which could be deadly if misapplied...
> >>
> >> The HV from a TV won't kill you, it just gives you one heck of a jolt!
> >>
> >> You may want to just use an old B&W or colour TV that you pick up at a
> >> thrift shop and use that as your HV source.
> >>
> >> It all depends on your application.
> >
> > Please see "Developing High Voltage pulses" June 5.
> > I have a functioning Pulser, but need a 12kV power source that will provide 2ma of current.
> > btw, do still see old CRT TVs at thrift stores?
> > Thanks, Mikek
> I have a pile of monitors here and flybacks as we service old arcade
> game monitors. You need 200ma at 120VDC if the flyback is lossless.
> Might be able to do that. You can use a B&W flyback as they tend to be
> running around 12KV and the primary side is pulsed 73VDC or so. 19"
> colour monitors flybacks run around 15 to 20KV at a B+ of 120VDC pulsed.
> Lower B+ would give lower output voltage of course.
>
> A common flyback is the GO7 Electrohome which runs at 15,xxx Khz and has
> built in HV diodes. I sell these here:
>
> https://flippers.com/catalog_oc/go7-electrohome-flyback-replacement-a-29951b
>
> You could use a picture tube as a smoothing filter cap I imagine...
> John :-#)#
or pick up a scrap crt tv
Cap can use glass sheets or jars, or wax soaked card. Test it to at least double run voltage - or that of course you need a cap.