Electronic Colour Change Systems   Description: Most textile weaving looms have a provision of change of colour of the weft thread. The system is called Dobby, The dobby is a mechanical device that has sensing pins which sense the hole in a punched film and on the basis of the hole the weft color is determined. The machine is programmed to give different colour design by the sequence of holes punched on this film.   There is one line of hole for every pic,  so after one pic the film moves up by one line and a next line comes in front of the sense pins. In this way the film moves on as the machine weave one thread after the other. This systems works fine if the design length is not that much (less Then 200 pics), but when the design repeat is large the length of the film becomes unmanageable and the operation of the machine gets difficult as the film is hard to mange and get stuck frequently. The long repeat is becoming a common situation since in modern looms the repeat is programmed not by punch film but by computers so our textile industry is facing a difficulty in meeting the requirement of the buyer’s in terms of the design repeat length. The only option available to them is to buy modern looms capable of long repeats, which is obviously a costly proposition.   Electronic Colour Change: The Electronic Colour change system was developed in order to convert the existing looms to handle long repeats. The unit consists of a microprocessor-based controller that is mounted on the machine. The controller has its 64k memory which is battery backed so that it can maintain long repeats in it memory even after power failure. The controller also has a mega tic control box that is mounted against the sense pins it is through this box that the controller sends signal to simulate the holes punch in the films so that for the machine it appears the same and there is no modification need in the machine.   Features: The electronic dobby generates the colour signals on the basis of the design kept in its memory. The design is first developed on the computer, the design is simply a copy of the punch film and consist of lines given with X (Hole punch) and a Dot (.) for no hole punch the design can be entered by any text editor on the computer with each test line representing one pic. Once the design is complete the file is copied transport the program from the computer into the electronic dobby. The Electronic Dobby has a 64k memory that can hold a total of 60,000 pics. The unit can hold ten different design at a time. The user can copy any design from the external memory into the unit. Any of the design can be selected to run on the machine. The Electronic Dobby has a keyboard that can be used to control its function once the program is selected the keyboard is locked so the no operator can fiddle with it. The dobby also has the provision of reverse pic and it will sense the reverse motion when the dobby wheel is moved in the reveres direction. Installation: The Electronic dobby is currently available on the sulzer 4 colour machine with a pin colour change dobby. It is also available on Sommit repier looms with eight colour in which the sensing is through photo transistor. The Electronic conversion of the floor dobby with 24 frame control is under development. Benefits: Generate long repeat. No running expense No addition cost of punch film with each design change. Easy to store, The design are kept in computer and no room for film storage is needed. Design can be changed in a few seconds. Multiple design can be maintained in the unit. No mechanical problems as there is no moving parts.