http://www.8051projects.net/ Learn to make simple microcontroller projects, pic, 8051, avr and arm projects. download 8051 projects, tutorials, libraries, sample codes. join the microcontroller discussion forum and ask doubts regarding electronics. the best source for 8051 over internet. en-gb 2009-01-07T22:43:09-08:00 contact@nospam.com hourly 1 2000-01-01T12:00+00:00 http://www.8051projects.net/forum-t7458.html 2009-01-07T22:43:09-08:00 Can i connect 5v relay to ULN2803A to drive 230V appliances such as fluorescence lamp? http://www.8051projects.net/forum-t7458.html 2009-01-07T22:43:09-08:00 fadhli which pin should i use? NC or NO? http://www.8051projects.net/forum-t7458.html 2009-01-07T22:43:09-08:00 sashijoseph Since the project has LED's connected it means for switching on the LED,the port pin is 0 and for switching off pin is 1.When you connect the ULN instead of the LED,the relay will be off when the command is for switching on and vice-versa.So you may connect the fl. bulb to the NC of the relay so that when the relay switches off(with the 'on' command),your bulb lights up. http://www.8051projects.net/forum-t7458.html 2009-01-07T22:43:09-08:00 fadhli sir,i don't have any idea how to check my circuit. can i show the picture of my circuit here? i've have to present this project on monday, now is already saturday. i can't finish my report if this project does not work. LoL http://www.8051projects.net/forum-t7458.html 2009-01-07T22:43:09-08:00 pdi33 well then , show us ur ciruit. attach it to ur post. To check ur relay connection across the uln chip, just connect a LED across the relay coil with a resistor in series so that it lights up when the relay is turned ON.