Exemplary embodiments include a sphere bar probe apparatus, including a holder, a retroreflector disposed in the holder, a member having a first end and a second end, wherein the first end is attached to the holder and an end plate attached to the second end of the member. The method includes applying a first voltage bias to a control gate of a selected memory cell in the flash memory array and applying a second voltage bias to a word line of the selected memory cell. Then low resolution and low speed analog to digital converters are used to sample each channels. A passband of the amplifier circuitry is changed from one operating frequency to another operating frequency by changing frequency conversion parameters of the feedback loop. The material has an inner surface opposite the vane providing a seal land in one example. The bowl portion has a width larger than that of the leg portion and includes a top open end facing the keycap, a bottom wall opposite to the top open end, a first contact extending upwardly from the bottom wall to contact the keycap when the keycap is pressed, and a second contact extending downwardly from the bottom wall to contact the circuit module when the keycap is pressed.