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Type A Crossover - Capacitors in series?


Robbie010

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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

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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.

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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.

 

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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

 

 

 

 

 

 

LTSPICE_1.jpg

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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.

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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
 

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