Check the listing for details. LM555 Timer Monostable (One-Shot) (#11701) Built & Tested. Condition: New. Listed at 10.99 USD. LM555 Timer One-Shot Monostable Kit #1. This little low-cost kit consists of the LM555 Timer in the One-Shot mode (Monostable). It was designed for those that need a Timer (or two) with no fancy circuitry. The output is a square-wave and is connected to the output pad. The output also drives a transistor which drives an LED, if you do not need the LED, simply do not install it. It works from 5v to 15v with the output voltage level the same as the Working Voltage. The circuit comes in 3 different frequency ranges. The PCB is 0.062" thick, 1.5" x 1.0", double-sided with Plated Thru Holes, silk screen on top side, Red soldermask. It has a 94VO rating and has one mounting hole. Built and tested comes without IC socket as it is already hard wired in.