Abstract: A partially devitrified porcelain enamel composition is formed by melting an oxide mixture in which 20-50 wt % BaO, 30-60 wt % SiO.sub.2, and 2-20 wt % TiO.sub.2 are present to form a homogeneous melt, quenching the melt to form a frit and firing the frit. The oxide mixture may optionally include K.sub.2 O, Na.sub.2 O, Li.sub.2 O, Al.sub.2 O.sub.3, B.sub.2 O.sub.3, As.sub.2 O.sub.3, CaO, CeO.sub.2, MgO, F.sub.2, N.sub.2 O.sub.5, PbO, P.sub.2 O.sub.5, Sb.sub.2 O.sub.3, SnO.sub.2, SrO, ZnO, ZrO.sub.2, and MoO.sub.3. Metal substrates coated with such a partially devitrified porcelain enamel composition are particularly suitable for the production of electronic circuits.

Abstract: A remotely operated downhole switching apparatus, particularly adapted to selectively connect a downhole device such as a sensor circuit to a cable which supplies power to a downhole motor includes a switch for connecting the downhole device to a neutral node of the motor, a latch coil responsive to a latching signal carried by the cable for closing the switch, and a delatch coil connected to the cable through a frequency responsive circuit which is responsive to a delatching signal carried by the cable for passing current through the delatch coil. A diode connected to the delatch coil prevents current flow through the delatch coil in a direction which causes the switch to close. An AC signal may be employed for closing the switch, and a voltage pulse may be employed for opening the switch.

Abstract: An indicating electronic timer useful for timing processing events and for controlling a process measures the elapsed time from a moment at which a process variable attains a predetermined value and produces a signal which varies in accordance with the elapsed time. During a timing operation, the signal is displayed on a display device which normally displays the process variable, and may be such that the display device indicates the percentage of a predetermined time interval which has elapsed. The timer may be conveniently implemented with relatively inexpensive integrated circuits, such as a variable oscillator, binary counters, and D/A converters.

Abstract: A remotely controlled switching apparatus for selectively controlling the connection of a downhole device to a power cable which carries power to a downhole motor includes a thermostatic switch connected between the device and the cable, and a heater for producing sufficient heat to raise the temperature of the switch above its operating temperature. The heater is operated by a switching signal impressed upon the cable by a control and readout unit on the surface. The apparatus may be used to disconnect the device from the cable for a predetermined period of time to enable high voltage testing. After the predetermined period of time, the apparatus automatically reconnects the device to the cable.