General-purpose sensor monitor

Sensors and transducers are interesting electronic devices to work with, but the snag is that their output signal invariably requires a made-to-measure amplifier that enables an indicator circuit to be driven. LDRs, temperature sensors, strain gauges, they all need an amplifier with very specific characteristics. The amplifier described here is designed to handle almost any sensor signal, has adjustable switching thresholds, and will be invaluable for quick experiments with a wide variety of sensors, both polarized and unpolarized.