Hello! First I=B4m want to thank You all for Yours enthusiasm and will to solve this problem out! My solution of the problem with the disturbance in the Norp12 circuit. I changed from NPN to PNP and placed the transistor before the relay winding then it works very good. My intention was to use a PIC as a timer to switch the light on/off on chosen times, but the PIC don=B4t be able to switch the PNP transistor on or off so I have to added a NPN transistor after the relay winding and now the circuit works properly. Regards =C5keN -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads