Electronic – Strange diode symbol in schematic

diodesschematicsymbol [~]

Does somebody know, what the parts "D1" (top left) and "D2" (bottom left) are? I would think it is a special kind of diode, but I never saw that symbol before in 10+ years of electronics.enter image description here

Best Answer

They look suspiciously like constant current diodes. These are devices usually made like JFETs but internally they have gate connected to source and produce a half-decent constant current. Here's the symbol: -

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Picture from iconfinder. Sometimes this symbol is used: -

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And Wikipedia has a nice article about them showing their relationship with a JFET: -

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