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Vintage Television and Video Vintage television and video equipment, programmes, VCRs etc. |
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1st Dec 2020, 12:12 am | #21 | |
Moderator
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Location: Fife, Scotland, UK.
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Re: How a Flyback works? induction and Ferris
Quote:
Firstly when the inductor (primary) is jammed across the supply to get some current going Supply voltage = - L.(di/dt) And that sets the slope of the current ramping up for whatever amount of time it gets. Then when the current is turned off you get E = -L(di/dt) where E is now th voltage transient and di/dt is the speed at which the switch can turn off the current. So you get a voltage step-up factor equal to the ratio of the turn off to turn on current change rates. This is the basis of the boost converter SMPS, and with a secondary overwind, the voltage can be scaled up still further as in TV EHT, car ignitions, and high-frequency arc initiation in TIG welders. Colour TVs go a step further and run the overwind into a voltage multiplying rectifier. David
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Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done |
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1st Dec 2020, 12:02 pm | #22 |
Dekatron
Join Date: Apr 2005
Location: North Wales, UK.
Posts: 6,884
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Re: How a Flyback works? induction and Ferris
On a practical level, I've used a non-metallic cable tie in the past and it has worked. Less successful has been when the ferrite core is cracked, chipped or broken.
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2nd Dec 2020, 6:04 pm | #23 |
Triode
Join Date: Dec 2011
Location: Wimborne, Dorset, UK.
Posts: 21
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Re: How a Flyback works? induction and Ferris
Hi All and thanks for all the contributions, im tempted with the cable tie but once fitted the LOPT has to be un-soldered each time a new one is needed. its not ideal because the engineer that’s fixing this chassis for me will have to do this when he repairs it and that means putting the metal top bracket on which might need to come off for access during repair. messy for him if he has to keep doing it, I don’t know if the bracket all needs to be tight and clamping the LOPT for testing. I would like to make a new clamp out of a material that won’t affect anything, im thinking about ordering a length of copper or brass. I realize that its not as strong as original but i have some deep 3mm nuts that should hold better on the threads. Can someone recommend a suitable material please? the old one was semi magnetic, be nice to know what that material was but i guessing one of the above should be safe?
Frazer |
2nd Dec 2020, 8:45 pm | #24 |
Triode
Join Date: Dec 2011
Location: Wimborne, Dorset, UK.
Posts: 21
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Re: How a Flyback works? induction and Ferris
notice that i call it a LOPT now
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2nd Dec 2020, 9:22 pm | #25 |
Pentode
Join Date: Apr 2011
Location: Westgate On Sea, Kent, UK.
Posts: 246
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Re: How a Flyback works? induction and Ferris
just a guess but maybe its alloy
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2nd Dec 2020, 9:50 pm | #26 |
Triode
Join Date: Dec 2011
Location: Wimborne, Dorset, UK.
Posts: 21
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Re: How a Flyback works? induction and Ferris
the original part thats broken stuck to the magnet but not as much as the mild steel one i made. perhaps original is stainless?
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2nd Dec 2020, 10:02 pm | #27 |
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Re: How a Flyback works? induction and Ferris
There are two classes of stainless steels: Austenitic and Martensitic. One is magnetic, the other isn't and I can never remember which way round they are.
David
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Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done |
2nd Dec 2020, 10:29 pm | #28 |
Dekatron
Join Date: Mar 2005
Location: Gateshead, Tyne and Wear, UK.
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Re: How a Flyback works? induction and Ferris
Googled austenitic and this came up:
Austenite, also known as gamma-phase iron (γ-Fe), is a metallic, non-magnetic allotrope of iron or a solid solution of iron, with an alloying element. In plain-carbon steel, austenite exists above the critical eutectoid temperature of 1000 K (727 °C); other alloys of steel have different eutectoid temperatures. DFWB. |
2nd Dec 2020, 11:24 pm | #29 |
Octode
Join Date: Sep 2017
Location: Bristol, UK.
Posts: 1,641
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Re: How a Flyback works? induction and Ferris
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3rd Dec 2020, 12:02 pm | #30 |
Triode
Join Date: Dec 2011
Location: Wimborne, Dorset, UK.
Posts: 21
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Re: How a Flyback works? induction and Ferris
Hi, i just want to order something lol.
I found some Stainless Steel T303 rod on ebay that says its non-magnetic, its cheap. The original is slightly magnetic... i wondering should i be looking for the magnetic variety? I found many types that are magnetic all with different chemical composition. Do you think this rod is supposed to be slightly magnetic for its function in the LOPT? if not ill order the T303 stuff. Ps for those that are interested, i will finish this thread with the final working monitor and a thanks to everyone. |
3rd Dec 2020, 8:31 pm | #31 |
Triode
Join Date: Dec 2011
Location: Wimborne, Dorset, UK.
Posts: 21
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Re: How a Flyback works? induction and Ferris
That was supposed to say:
Ps for those that are interested, i will finish this thread with a picture of the final working monitor + a thanks to everyone for helping. ive ordered the Stainless Steel T303 |
11th Dec 2020, 6:30 pm | #32 |
Triode
Join Date: Dec 2011
Location: Wimborne, Dorset, UK.
Posts: 21
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Re: How a Flyback works? induction and Ferris
Hi All, thought i would update.
I got my 304 stainless through and because i didn't want to mess it up, i made a former to help. Here is the new clamp in place, note the insulating plastic feet on the bottom of the ferrite. I was careful to make sure they went back in. |
11th Dec 2020, 6:31 pm | #33 |
Triode
Join Date: Dec 2011
Location: Wimborne, Dorset, UK.
Posts: 21
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Re: How a Flyback works? induction and Ferris
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11th Dec 2020, 6:33 pm | #34 |
Triode
Join Date: Dec 2011
Location: Wimborne, Dorset, UK.
Posts: 21
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Re: How a Flyback works? induction and Ferris
Its packaged up and off the the chap for repair now.
Frazer |
11th Dec 2020, 7:03 pm | #35 |
Hexode
Join Date: Nov 2010
Location: Sheffield, South Yorkshire, UK.
Posts: 278
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Re: How a Flyback works? induction and Ferris
Nice bit of engineering there, good to see a workbench too
Regards,Alan |