electronic code locking system | Projects › Projects › electronic code locking system This topic has 1 reply, 2 voices, and was last updated 9 years, 6 months ago by Ashutosh Bhatt. Viewing 2 posts - 1 through 2 (of 2 total) Author Posts February 5, 2015 at 6:06 pm #3429 Rosie maryParticipant How do we have to connect the relay??which pin should be given to led and which pin to the collector of the transistor in those 3pins??wat abt com??reply soon please.. February 17, 2015 at 6:06 pm #12619 Ashutosh BhattParticipant normally PCB mount relay (suger cube type) are called 1 change over or 2 change over type relays they have 5 or 8 connections – terminals in 1 C/O type relay there are 5 terminals. 2 for coils and 3 for C, NC and NO from these one of the coil terminal is connected to +Ve supply, second is connected with collector of transistor C, NC and NO are for connecting device or load Author Posts Viewing 2 posts - 1 through 2 (of 2 total) You must be logged in to reply to this topic. Log In Username: Password: Keep me signed in Log In