Abstract: An example sample-and-hold circuit includes a first and second input resistors, each having first and second terminals; first and second transistors coupled in series between the second terminals of the first and second input resistors; and third and fourth input resistors, each having first and second terminals; and third and fourth transistors coupled in series between the second terminals of the third and fourth input resistors. A first capacitor is coupled between the first and second transistors and a second capacitor is coupled between the third and fourth transistors. The control terminals of the first and third transistors are coupled together, and the control terminals of the second and fourth transistors are coupled together.

Abstract: A dispenser cap includes a shell, a scraper coupled to the shell, and a fluid-delivery controller. The dispenser cap mounts on a spray can, and the fluid-delivery controller engages with a valve of the spray can to selectively dispense pressurized fluid from the spray can.

Abstract: Cleaning compositions include (a) a carrier liquid; (b) a metal citrate and/or a plurality of reagents configured to generate the metal citrate in situ; (c) one or a plurality of non-ionic surfactants; and (d) an organophosphate hydrotrope configured to increase solubility of the one or the plurality of non-ionic surfactants in the carrier liquid. Methods for cleaning engine cooling systems are described.

Abstract: A dispenser cap includes a shell, a scraper coupled to the shell, and a fluid-delivery controller. The dispenser cap mounts on a spray can, and the fluid-delivery controller engages with a valve of the spray can to selectively dispense pressurized fluid from the spray can.

Abstract: Cleaning compositions include (a) a carrier liquid; (b) a metal citrate and/or a plurality of reagents configured to generate the metal citrate in situ; (c) one or a plurality of non-ionic surfactants; and (d) an organophosphate hydrotrope configured to increase solubility of the one or the plurality of non-ionic surfactants in the carrier liquid. Methods for cleaning engine cooling systems are described.

Abstract: Disclosed herein is a composition comprising a formula emulsion wherein the formula emulsion comprises a cationic or amphoteric surfactant, a wax emulsion, a thickener, and at least two silicone oils having different viscosities, wherein the composition is free of abrasives and organic solvents. The weighted average viscosity of the silicone oils is 2200 to 2400 centistokes (cSt).