Abstract: A method for manufacturing a solar cell includes providing a first conductivity type doped crystalline silicon wafer, depositing on one side a first intrinsic a-Si:H buffer layer, followed by a second conductivity type doped a-Si:H layer, turning over the wafer and depositing on the opposite side a surface passivating anti-reflection coating, applying a first mask having a grid opening on the second conductivity type doped a-Si:H covered surface of the wafer, dry etching to remove the second conductivity type doped a-Si:H layer not covered by the first mask, while maintaining the first mask in position: depositing a second intrinsic buffer layer of a-Si:H, depositing a first conductivity type doped a-Si:H layer.

Abstract: A method for manufacturing a solar cell includes providing a first conductivity type doped crystalline silicon wafer, depositing on one side a first intrinsic a-Si:H buffer layer, followed by a second conductivity type doped a-Si:H layer, turning over the wafer and depositing on the opposite side a surface passivating anti-reflection coating, applying a first mask having a grid opening on the second conductivity type doped a-Si:H covered surface of the wafer, dry etching to remove the second conductivity type doped a-Si:H layer not covered by the first mask, while maintaining the first mask in position: depositing a second intrinsic buffer layer of a-Si:H, depositing a first conductivity type doped a-Si:H layer.

Abstract: A monitor and indicating circuit for use with a reverse osmosis filter for signaling the need for servicing of the filter comprises first and second conductivity cells respectively located in the water inlet and outlet pipes of the filter. An AC signal of a predetermined frequency and amplitude is used to drive an op amp whose input resistance comprises the outlet conductivity cell and whose feedback impedance comprises the inlet conductivity cell. Normally, the resistivity of the outlet conductivity cell is substantially larger than the resistivity of the inlet conductivity cell, assuming that the filter is functioning properly. As the ROF fails, the resistivity at the outlet approaches that at the inlet thereby increasing the gain of the variable gain amplifier. The output from the variable gain amplifier is then peak detected and applied to a comparator where it is compared to a predetermined reference voltage.

Abstract: A signal responsive circuit especially adapted for use in a water treatment system for signaling the need for regeneration of an ion exchange resin bed or the replacement of a particulate filter medium. A series of three electrodes are disposed in the water treatment medium in longitudinally spaced relation along the direction of flow and an alternating current signal drives the center-most electrode. The two outer electrodes are coupled as inputs to first and second operational amplifiers having asymmetrical gain characteristics. When the effective resistance between the center electrode and the two outer electrodes are equal, which is the condition prior to the movement of the hardness front or contamination front to the location of the electrodes, a first signal output condition exists.

Abstract: A method and apparatus for initiating the regeneration cycle of an ion exchange resin type water softener based upon the movement of the "hardness front" through the resin bed as water being treated is passed therethrough. Electrical probes are provided at predetermined longitudinally spaced locations and the difference in potential between the probes is measured, as is the rate of change of this potential with respect to time. It is found that as the hardness front passes between the probes, a detectable change in potential occurs which may be applied to an electronic circuit for generating a control signal which may initiate the regeneration cycle of the water softener subsequent to the arrival of the hardness front in the zone between the probes.