Abstract: A lighting device (132) includes a circuit having a power supply and a plurality of light emitting diodes (120) connected in series with the power supply. The plurality of light emitting diodes (120) includes at least two groups of series-connected light emitting diodes, the groups of series-connected light emitting diodes being connected in series. A different optically isolated field effect transistor (U3-U5) is connected in parallel with each group of series-connected light emitting diodes, for selectively shunting around the group of series-connected light emitting diodes. A different capacitor (C8-C10) can also be connected in parallel with each group of series-connected light emitting diodes. A controller (U2) is connected to a gate of each of the optically isolated field effect transistors (U3-U5) for selectively turning the optically isolated field effect transistors (U3-U5) on and off.

Abstract: The filter device has a housing with elongated top and bottom walls and side walls which taper inwardly from top to bottom. The top wall has extending downwardly therefrom into the housing a generally flat filter membrane support with a quadrangular periphery, a pair of filter membranes being disposed on opposite sides of the support and sealingly bonded to its periphery, the support having a center portion with spaced coplanar surfaces on each side to provide support for the center portion of the filter membranes. The housing is provided with an opening communicating with the space between the two filter membranes and with an opening communicating with the space between the housing and the two membranes.

Abstract: The disposable filter device of the invention is particularly suited for testing for the amounts of tars and nicotine in cigarettes and comprises a housing having two components (2,4) one of which has a cylindrical portion (8) and the other of which has an annular flange (48) whereby the two members can be telescoped together with a filter disc (6) therebetween for collecting the tars and nicotine. The member with the cylindrical portion is formed of a relatively soft resilient substantially non-hygroscopic polymer and the member with the annular flange is formed of a relatively hard substantially non-hygroscopic polymer. The resiliency of the member with the cylindrical portion in combination with the relative hardnesses of the members and the particular shapes of the telescoped portions (12,48) enables the two members to be removably secured together with an excellent seal therebetween.