[GreenKeys] Loop supply options

[Harold Hallikainen]

I note that the output voltage on
https://www.mouser.com/ProductDetail/International-Power/IHB120-02?qs=MKoP7Oyr0W4tUbkG3QpCWg%3D%3D
is adjustable, so that could be used as a loop current adjust. It also
appears to have an internal current limiter at 200 mA. If that turns the
supply into a current source and that current limit could be decreased to
60 mA, that could also be used. Finally, whatever is keying the loop from
a radio receiver could be set as a "constant current" device switching the
current between 0 mA and 60 mA. This might take the form of a bipolar
keying transistor with an emitter resistor setting the current limit based
on the base voltage. There WILL be dissipation, but there is always going
to be some somewhere, either in an active device or a resistor.

Harold


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