Driving relay with low current

  • Thread starter jbord39
  • Start date
  • #1
74
0

Main Question or Discussion Point

Hey. I am trying to use a single quick pulse of about 2.5 mA to run a latching relay. I know that this signal needs to be amplified (probably with a transistor) but am unfamiliar on how to do this.

Thanks for the help,

John
 

Answers and Replies

  • #2
1,482
3
Here is a relay driver. The diode in this circuit is used to protect the transistor from high voltage that is being induced by the relay coil.


http://www.vlearnvshare.com/home/images/articles/NPN-DRIVER1.GIF [Broken]
 
Last edited by a moderator:
  • #3
4,662
5
If the relay current is over 50 milliamps, you should use a Darlington transistor, such as the TIP120 (available at Radioshack) or equivalent. See datasheet

http://www.learn-c.com/tip120.pdf

The current gain at saturation is ~250. You should also have a 10k resistor from the data input to ground.

Bob S
 
  • #4
74
0
Thanks for the help. I'm going to get the parts today so I'll let you know.
 

Related Threads for: Driving relay with low current

Replies
20
Views
14K
Replies
1
Views
2K
  • Last Post
Replies
6
Views
693
Replies
2
Views
829
  • Last Post
Replies
1
Views
765
Replies
1
Views
3K
Replies
3
Views
10K
  • Last Post
Replies
8
Views
6K
Top