I'm building a dev board for microprocessors - but ran into confusion when drawing up the circuitry for the power terminals and the associated LED indicators.
I am in need of two LEDs - a power-good indicator (simple LED across the terminals): and a "power-in-use" indicator that, with any luck, wont interfere too much with the rest of the circuitry.
The purpose of this is to indicate if there is any current being drawn by the header pins (which serve as a power source for anything on the dev board)
What is the best way to do this?
I had a couple of ideas on using transistors but I'm inexperienced with their usage.
Attached is one circuit I thought might work - though the top "header connected indicator" made me wonder what would actually happen were it wired like this? I doubt it will work as expected - but at the same time I can't figure out what would actually happen! (I'm away from my workshop and can't make a mockup just now). Incidentally, are those two resistors in parallel when the jumper is connected?)
My other problems was that of any resistors I put across the terminals would end up in parallel to any circuitry downstream of the headers - would I be right in saying I can reduce or isolate that problem using transistors as switches?
Many thanks!