mboxler Posted January 26, 2020 Share Posted January 26, 2020 My apologies @John Warren . I've never used LTspice, and didn't understand the schematic. I've been using iCircuit and XSim, but can't simulate transformers/autotransformers. This link is interesting. Inductors are used along the a K-statement to mutually couple the inductors. Both transformers and auto transformers are discussed. I'm playing with LTspice now. Slow learner. https://www.analog.com/en/technical-articles/using-transformers-in-ltspice-switcher-cadiii.html Quote Link to comment Share on other sites More sharing options...
glens Posted January 26, 2020 Share Posted January 26, 2020 I fetched a copy of LTSpice to play with in a windowed instance of W98 last night myself because I want to perform the analysis I requested earlier. That linked article doesn't pertain in this case since there is only one winding in your transformer. Quote Link to comment Share on other sites More sharing options...
John Warren Posted January 26, 2020 Share Posted January 26, 2020 33 minutes ago, glens said: That linked article doesn't pertain in this case since there is only one winding in your transformer. That's because it's not a Transformer it's an Autotransformer. Autotransformers have only one winding and in the case of the little model I posted, it's only the -3dB tap. Quote Link to comment Share on other sites More sharing options...
John Warren Posted January 26, 2020 Share Posted January 26, 2020 2 hours ago, mboxler said: My apologies @John Warren . I've never used LTspice, and didn't understand the schematic. I've been using iCircuit and XSim, but can't simulate transformers/autotransformers. This link is interesting. Inductors are used along the a K-statement to mutually couple the inductors. Both transformers and auto transformers are discussed. I'm playing with LTspice now. Slow learner. https://www.analog.com/en/technical-articles/using-transformers-in-ltspice-switcher-cadiii.html Learning LTSPICE is simple, it's developing the circuits that takes time. If you'd like I show you how it can be used but on my site. I'll put a forum up called LTSPICE and we can noodle it there. Some examples of models: Crown D45 Quote Link to comment Share on other sites More sharing options...
John Warren Posted January 26, 2020 Share Posted January 26, 2020 Crown XLI1500 with a built in active filter Quote Link to comment Share on other sites More sharing options...
John Warren Posted January 26, 2020 Share Posted January 26, 2020 A transformer with one of the secondary's loaded to estimate power requirements for the devices: Quote Link to comment Share on other sites More sharing options...
John Warren Posted January 26, 2020 Share Posted January 26, 2020 LK-72A preamp section with models for the 12AX7 preamp tubes: 1 Quote Link to comment Share on other sites More sharing options...
glens Posted January 26, 2020 Share Posted January 26, 2020 34 minutes ago, John Warren said: That's because it's not a Transformer it's an Autotransformer. Autotransformers have only one winding and in the case of the little model I posted, it's only the -3dB tap. Yes, as I'd said. Transformers come in a wide variety of configurations, one of which is a multiple-tapped single winding. Quote Link to comment Share on other sites More sharing options...
mboxler Posted January 27, 2020 Share Posted January 27, 2020 It wasn't pretty, but I got some numbers out of LTspice. I modified my test board and came up with 12.769uf and 2.077uf values. When I plugged these cap values into LTspice, I came up with voltages that were very close to what I measured with my Fluke meter. Back to LTspice... Again, 2.83 volts 400 hz, 14.2 ohm K-55, and 8 ohm K-77. Capacitors 13uf and 2uf. Classic Type A K-55 1.276 volts K-77 .074 volts 2uf cap moved to amplifier input K-55 1.38 volts K-77 .114 volts (3.6 db increase) 13uf and 2uf in series with K-77, no connection to autoformer K-77 .0985 volts My autoformer model is a work in progress. I'm curious what voltages others end up with. Mike 1 Quote Link to comment Share on other sites More sharing options...
JohnA Posted January 28, 2020 Share Posted January 28, 2020 Perhaps the old man knew a thing or 2. 🤣 I need to decide whether I should return my Type AA tweeter input to the autoformer. Quote Link to comment Share on other sites More sharing options...
Deang Posted January 28, 2020 Share Posted January 28, 2020 If you want it to be an AA you do. 😉 2 Quote Link to comment Share on other sites More sharing options...
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