An LED light string employs a plurality of LEDs wired in block series-parallel, where the one or more series blocks, each driven at the same input voltage or rectified AC input voltage as the source voltage (110 VAC or 220 VAC), are coupled in parallel. This voltage matching requirement for direct AC drive places fundamental restrictions on the number of diodes on each diode series block, depending on the types of diodes used. The same method that apply to matching the sum of the LED lamps (VAC values) to the AC input, or applied voltage in an AC circuit apply to matching the sum of the LED lamps (VP values) to the full-wave or half-wave rectified AC (VP) voltage applied. Filtering capacitors may also be employed.