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What is the name of this device?

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Peter Mortensen
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Szymon M.
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  • It doesn't make a lot of sense in this context, but I've seen a similar symbol used to denote a constant current source or current mirror. Take a look at page 17 of [this application note from TI](http://www.ti.com/lit/an/slva051/slva051.pdf). – Caleb Reister Jun 05 '17 at 04:06

1 Answers1

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It's the symbol for an adjustable transformer. See yourself:

enter image description here

M.Ferru
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  • What is the difference between a variac transformer and the transformer that is shown? They both adjust the output voltage but have different symbols? – Szymon M. Jun 04 '17 at 22:39
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    @SzymonM. I never use such transformer... I just know the symbol. I suggest you to make a new topic [here](https://electronics.stackexchange.com/questions/ask). Explain clearly what you know and what is your question. People will answer quickly – M.Ferru Jun 04 '17 at 22:42
  • @SzymonM. There are lots of symbols and names. The challenge when looking at any schematic is identifying what specific symbols mean. Adjustable transformer = variac = autotransformer = variable transformer. – StainlessSteelRat Jun 04 '17 at 22:49
  • I would assume that the overlapping circle symbol implies that the coupling between primary and secondary can be varied. A variac is an autotransformer (single winding) where the output connection can be moved along the transformer winding to vary the output voltage. Your symbol may be something only used in power distribution. I haven't seen anything like it while working in electronics. – Peter Bennett Jun 04 '17 at 23:55
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    StainlessSteelRat: No, they're not the same. A Variac is an "autotransformer", a transformer with just one winding and three, not four terminals. Its output is an adjustable tap. This symbol denotes a more conventional transformer with two windings but with variable inductance. Not the same thing at all. – Jamie Hanrahan Jun 05 '17 at 01:14
  • @StainlessSteelRat Autotransformer does not have to be adjustable, adjustable transformer does not have to be auto. Eg 2×25kV railway uses nonadjustable 2:1 autotranformers to save on loses in steel rails, while as a kid I had a variable, fully insulating transformer to power model trains (PIKO FZ1). "Variac" is a brand name, so it has marketing meaning, not a technical one (although it technically is both auto and variable). – Agent_L Jun 05 '17 at 08:16