In an electronics lab, an instrumentation amplifier can measure microvolt (µV) DC voltages, a feature that can be useful for a range of interesting physics and engineering experiments like Hall effect, potentials, photocurrent effects, etc. To minimize input offsets and earth loops that can cause errors when measuring small DC signals, the flying capacitor (or switched capacitor) technique used in its input stage provides a true differential input. Made from off-the-shelf components, this design can be realized fairly cheaply.