How to use ULN2003A?

[niukasu]

I am a student without any EE background.
I noticed that there are some posts answering how to use ULN2003A, but it does not work for me.
Take this one as an example,https://www.ti.com/lit/ds/symlink/uln2003a.pdf
I connected 2 9V battery and a relay in series. Then I connected the positive side to 1C, and the negative side to COM. After that, the relay switched.
I don't understand why. Doesn't it require an input in 1B if I want 1C work?
What should I do to make the relay switched work only if there is an input in 1B? The current situation is the relay switches even though there is no input in 1B

 

[sivamani]

Check weather it is working on reverse logic?
What happens when you give input?

 

[amayilsamy]

Check your relay driving circuit and current of relay.

Try this link

http://digital-diy.com/general-electronics/99-tip-relays.html

Post your schematic?

 

[chuckey]

"e negative side to COM. After t" The negative side of the battery should go to E. The COM terminal should be connected to batt+. It is to suppress voltage spikes when switching inductive loads, like relays.
Frank

 

[uday mehta]

send your circuit diagram.