Abstract: A constant force probe to test electrical and electronic circuits is disclosed whereby the magnetic repulsion between a magnet supporting the probe tip and an electromagnet contained within a housing is used to deform a load cell which provides an electrical output representative of the force of engagement between the probe and the test specimen. The electronic output signal from the load cell then is used for comparison purposes with preset signals, and the electrical current to the electromagnet within the probe housing is modulated to adjust the force exerted by the probe onto the workpiece by changing the flux density of the magnetic field generated by the electromagnet.