This easily accommodates 4.5V battery applications, but is far too marginal for 3V applications. By following the application information indicated on the schematic, it may be extended to 28V. The ...

Choosing athree-cell, 4.5V supply results in a lowervoltage of 0.33V per cell. A 4.5V supplycan power as many as eight LEDs.Tests show that this circuit works from4.5V to 0.94V, which is lower than ...