25+ Posting Member
737 MIP TEST/DIM switch
Can anyone share solution with DIM function of this switch? I have 17 mip annunciators, wich lighting intensity must be reduced by this switch.
It means, that for each annunciator I need separate resistor (additional to that one, wich is used with leds by default). And I have to bypass this resistor, when the switch is in middle position (DIM is not activated). That how I see it.
Now a question - how to circuit? I have now only idea to use 17 transistors. Such solution will allow to use only one output (connected to DIM switch with SIOC) of IO card shared between all transistors base. When transistor is open, resistor (used for DIM function) will be by-passed. Otherwise, it will limit current and, consequently, light intensity. Probably, there's more rational solution?
I also know, that there's PWM dimming function in USBOUTS, wich is used for annunciators in my project, but it's shared between all outputs. Isn't it?
So, I would appreciate any comments on this issue