Inductor-Free Driving of Single/Two Cell White LED

The project allows a white LED or UV LED to be driven from one-cell or two-cell batteries without the use of inductors.

Four transistors are required when two 3V cell circuits are used while six transistors will be required on a single 1.5V cell although the brightness of the LED will not be as high as the two-cell circuit. 13 transistors will be required for higher output single cell which will provide the same brightness with the two-cell circuit.

The white and UV LEDs require high operating voltage which can range from 2.8V to 4V depending on the operating current and the individual device. A 4V LED can be driven easily by a 9V transistor radio battery by placing in series the correct resistor. The most expensive of the common primary batteries is the 9V transistor radio battery but has a low energy capacity.

The alkaline and carbon zinc flashlight cells are the primary batteries that are priced by the cell rather than the available energy. A bigger flashlight cell would cost more than a smaller cell since the bigger cell is capable of delivering much more than twice the energy.

Rest of the project