Path: ...!news.nobody.at!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail From: Klaus Vestergaard Kragelund Newsgroups: sci.electronics.design Subject: Re: CCFL transformer Date: Thu, 25 Apr 2024 22:23:31 +0200 Organization: A noiseless patient Spider Lines: 79 Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Injection-Date: Thu, 25 Apr 2024 22:23:31 +0200 (CEST) Injection-Info: dont-email.me; posting-host="4b5c888e51d2a6be223cc6358a08a070"; logging-data="3365818"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX18YlTBGQzcfZQP9MKZa9slVZN5ImhZUFRE=" User-Agent: Mozilla Thunderbird Cancel-Lock: sha1:4IaX0p2U7NgQr2YXjqwPkCcI0QE= In-Reply-To: Content-Language: en-US Bytes: 3865 On 25-04-2024 17:08, John Larkin wrote: > On Thu, 25 Apr 2024 10:18:42 +0200, Klaus Vestergaard Kragelund > wrote: > >> On 24-04-2024 16:23, John Larkin wrote: >>> On Wed, 24 Apr 2024 09:37:24 -0400, legg wrote: >>> >>>> On Wed, 24 Apr 2024 01:57:36 +0200, Klaus Vestergaard Kragelund >>>> wrote: >>>> >>>>> Hi >>>>> >>>>> I need a low distributed capacitance winding transformer, for a HV >>>>> stepup function (3.5kV) >>>>> >>>>> I am zeroing in on similar concept as CCFL transformers with >>>>> sectionalized bobbin. >>>>> >>>>> For example: >>>>> >>>>> https://www.coilcraft.com/en-us/products/transformers/power-transformers/ccfl-transformers/fl/ >>>>> >>>>> Possibly using Triple Insulated Wire to create some distance between the >>>>> individual turns. >>>>> >>>>> Not many sells CCFLs these days. >>>>> >>>>> Guess I will keep it alive.... >>>>> >>>>> Regards >>>>> >>>>> Klaus >>>> >>>> When there are a lot of turns, 3xFEP is not the way to >>>> go. Too bulky. The three layers is basically a trick to >>>> avoid creepage requirements for pri-sec safety. That's >>>> not what you need here. >>>> >>>> Anything off the shelf will be a great time saver. >>>> >>>> RL >>> >>> I sometimes use an autoflyback stage with a DRQ-series dual inductor, >>> followed by a c-w multiplier using sot-23 dual HV diodes. That's cheap >>> and easy, given a reasonable supply voltage, like 24. >>> >> >> I cannot use capacitive doubler thingies, there's no output DC voltage. >> >>> You can also just buy a potted HV supply and move on to design >>> something else. >>> >> >> I need it cheap, so cannot buy COTS >> >>> There are also potted c-w bricks, but they are a lot more expensive >>> than buying the diodes and caps. >>> >>> Custom magnetics only makes sense at high volume, or for real exotica >>> like transmission-line transformers. >> >> I have almost never used standard magnetics. Most projects has >> requirements that dictate custom, or in higher volumes price is the key. >> >>> >>> I'm about to embark on a custom tapped inductor and I'm not looking >>> forward to it. Drawings, quotes, revised drawings, more quotes, >>> samples, tests, released drawings, MOQs, all that. >>> >> >> Yeah, boring work. > > What input do you have, and what output do you want? > I have 24VDC in, and 3.5kV peak pulse with 10% duty cycle at 100kHz. I have a working circuit, but just a little too much loss due to the transformer parasitics, so working to change the construction to get the optimum transformer design