Maker Pro
Maker Pro

in need of some comparator help

japcarmad

Oct 2, 2013
4
Joined
Oct 2, 2013
Messages
4
hi,
just joined up to get some advice on a simple circuit that require for an automotive project

my goal - to build a simple device that can trigger a relay at a given voltage for example. my range of input is 0 - 5 v. i need to turn on a relay at 1.5v, 3v and 4.5v. possibly 3 identical circuits to operate 3 devices each at these given voltages.

i have been looking for a while on the net and think i need to use a LM2903 comparator IC to control a transistor and in turn operate the relay.

i have fundamental electronics knowledge but need further help to figure out where to go from here.

many thanks in advance
 

shrtrnd

Jan 15, 2010
3,876
Joined
Jan 15, 2010
Messages
3,876
The most valuable asset people WITH fundamental electronics knowledge have, are
the manufacturer's data sheets, on the devices we use.
People here can help where you need it. Did you find and check the data sheet
for the LM2903? Check it and see if it might do what you want it to do, and we can
help you go from there. If you see a problem on the data sheet with the LM2903, let us
know what it might be, and we can help with modification of the circuit or recommendation
of something else that might work.
We like to help, we kind of shy away from doing leg-work that you should be doing.
 

duke37

Jan 9, 2011
5,364
Joined
Jan 9, 2011
Messages
5,364
Welcome to the forum.

You could look up the data for the LM3914 bargraph display driver. This has 10 comparators and you can connect to the appropriate outputs. It has a built in voltage reference.
 

japcarmad

Oct 2, 2013
4
Joined
Oct 2, 2013
Messages
4
i was actually just looking at an led bar graph that can be calibrated. i could use the output to the led to trigger a relay.
 
Top