View Full Version : How to drive a latching relay

11-03-2009, 07:57 PM
I want to drive a latching relay with Basic Stamp 1, A remanent core latching relay requires a current pulse of opposite polarity to make it change state.·Relay operates with 9V and·300 milliamp, pullse duration to chage state is about·200milisec.

Please help me to find the parts and draw the circuit. I have basic electronic knowledge.



Mike Green
11-03-2009, 09:52 PM
There are plenty of examples in a number of Stamp tutorials and articles. Start with Nuts and Volts Column #6. Go to Parallax's main webpage and click on the "Resources" tab. Near the bottom of that page, you'll see a link to the Nuts and Volts Columns index. #6 is in volume 1.

Because it sounds like you need alternating polarity pulses, you may need what's called an H-bridge. The StampWorks Manual gives examples of this using a H-bridge IC (L293), but the same idea also works with discrete transistors. The Wikipedia has a nice article on H-bridges as well as links to practical examples. Do a Google search for "wiki H-bridge".

Post Edited (Mike Green) : 11/3/2009 2:57:50 PM GMT

11-03-2009, 10:11 PM
Thanks Mike, I will check them.

Ron Czapala
11-04-2009, 11:20 AM
You can also buy latching relays that latch with·a pulse·to one pin·an unlatch with a·pulse to a different·pin. You would not need to reverse polarity.

11-04-2009, 08:23 PM
The latching relay I use is a custom designed product for a particular aplication, other relays physically would not fit in to the assembly. Therefore I have to use what I have.