I am not a experienced designer for circuits and was hoping someone in here could assist me with a project i wanted to do. Background:- In the field of traffic signals testing and commissioning we have to check the correct inductive loop is connected to the correct input in the traffic signal controller. to do this it take two people, one to pass a metal object over the loop position and another to look at the LED's on the detector pack and see if they can identify the correct channel of input being triggered by the metal object. There are problems on large sites with communications between the two engineers and the triggering of other inductive loops by traffic and hence possible false identification. To overcome this i proposed to build a circuit that would produce a variable pulse pattern either mark to space variable or applitude or patterns of pulses to make the identification easier to differentiate from the background detections. I also wanted to mount this in a traffic cone so that we could place the traffic cone over a corner of a loop and the cars would avoid it. this would save have two engineers on site. of course this unit would have to be battery fed, not to bulky, able to transfer its pulse via a loop on the base of the cone to the loop in the ground ( note most inductive loops in the ground are arouns 15cm depth and around 3 to 5 turns). any help would be greatly appreciated.