My Circuit

This LED lamp was originally designed for use on a budget solar-charged 12V electrical system. It is bright enough for comfortable reading at night and features constant LED brightness with diminishing battery voltage. The circuit uses six high-brightness white LEDs mounted in a 90mm diameter reflector. The upper half of a stainless steel ice cream bowl makes a good reflector but almost any torch reflector of a similar size will do. As shown, two banks of three series-connected LEDs are powered from a 12V (nominal) DC supply. The LEDs used are rated at 20mA maximum with a measured voltage drop of 3.2V. Circuit diagram: Economical Desk Lamp Circuit Diagram For Camping Each bank combines an inexpensive LM334 current source IC with a BC558 transistor to provide a constant 20mA to the LED string. Basically, the LM334 controls the base current of the BC558 such that 64mV appears between its "R" and "V-" terminals. With the 3.3O resistor shown, this results in close to th...

Circuit Diagram  Description   The automatic pump controller eliminates the need for any manual switching of pumps installed for the purpose of pumping water from a reservoir to an overhead tank (refer Fig. 1). It automatically switches on the pump when the water level in the tank falls below a certain low level (L), provided the water level in the reservoir is above a certain level (R). Subsequently, as the water level in the tank rises to an upper level (M), the pump switched off automatically. The pump is turned on again only when the water level again falls below level L in the tank, provided the level in the reservoir is above R. This automated action continues. The circuit is designed to ‘overlook’ the transient oscillations of the water level which would otherwise cause the logic to change its state rapidly and unnecessarily. The circuit uses a single CMOS chip (CD4001) for logic processing. No use of any moving electro-mechanical parts in the water-level sensor has bee...