I've made a board which supplies multiple Zinc Oxide gas sensors with 5V (they need a 48 hour burn-in according to the mfg).
It would be nice to shine an LED when a sensor is plugged in, but I have 5.0V rail already (the recommended value), and I do not want to drop more than say 10mV for sensing.
(Note: For now at least, I'm accepting the mfg strict guidelines of 5V (+/- 0.1V), even though I suspect it is not so critical, especially for this conditioning phase).
I'd like to avoid using say 1 op-amp per sensor, and I hope it is possible with maybe 1 transistor per sensor...