I'm currently designing an anemometer that utilizes a Wheatstone bridge within a feedback loop. My attached schematic is not a Wheatstone bridge, but it is the most simplified way to ask my question.
Essentially I have a voltage input to the top of the circuit which can range from 0V to -15V (as a result of closed loop feedback not shown in the diagram). I would like to have an LED light up if R2 is broken. It is imperative that whatever is added to this circuit does not impact the circuit function or it will be detrimental to the feedback (whatever is attached should have very high impedance and be powered separately). I have separate references of +15V, -15V, and Ground available.
Logically, this means that the voltage at point 1 (dashed circle) will be zero and at point 2 will be not zero (I don't need the LED to go off when there is 0V coming in). I thought I could use two comparators feeding into an AND logic gate (which would power an LED), but the negative voltage is throwing me off and there are many properties of both comparators and AND chips that are not easy to a novice (open collector, TTL, CMOS).
Any suggestions on strategy, or at least point me in the right direction of part names to look at or solutions to similar problems? I feel like I'm making this more difficult than it seems.
Essentially I have a voltage input to the top of the circuit which can range from 0V to -15V (as a result of closed loop feedback not shown in the diagram). I would like to have an LED light up if R2 is broken. It is imperative that whatever is added to this circuit does not impact the circuit function or it will be detrimental to the feedback (whatever is attached should have very high impedance and be powered separately). I have separate references of +15V, -15V, and Ground available.
Logically, this means that the voltage at point 1 (dashed circle) will be zero and at point 2 will be not zero (I don't need the LED to go off when there is 0V coming in). I thought I could use two comparators feeding into an AND logic gate (which would power an LED), but the negative voltage is throwing me off and there are many properties of both comparators and AND chips that are not easy to a novice (open collector, TTL, CMOS).
Any suggestions on strategy, or at least point me in the right direction of part names to look at or solutions to similar problems? I feel like I'm making this more difficult than it seems.
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