A decorative light string is provided that includes a plurality of light emitting diode (LED) illumination assemblies electrically connected in series and a stabilizing current or voltage circuit. Each of the plurality of LED illumination assemblies includes an LED. The stabilizing current or voltage circuit is electrically connected in series with the plurality of LED illumination assemblies. The stabilizing current or voltage circuit is configured to receive input power from an input power source and configured to supply a stabilized current or voltage to the plurality of LED illumination assemblies that provides a stable supply even with input power source fluctuations. Power fluctuations from an input power source can prevent the decorative light string from maintaining a desired brightness and desired LED life unless the voltage or current to the LED illumination assemblies is stabilized.