latching a relay problem
Printed From: the12volt.com
Forum Name: Relays
Forum Discription: Relay Diagrams, SPDT Relays, SPST Relays, DPDT Relays, Latching Relays, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=134034
Printed Date: April 28, 2024 at 8:13 AM
Topic: latching a relay problem
Posted By: chicyan
Subject: latching a relay problem
Date Posted: April 15, 2013 at 5:43 AM
I have a problem with my relay, it wil not latch. My input on the relay it 12volt, but the relay wont latch. i measured the input when the relay is wired, and the 12volt source falls to 2.5volt. I also mesured the amps and my source seem to only put out 150ma, so if i'm not mistaken a relay coil need at least 250ma to latch ?? Any way i can do a easy fix ?? a smaller relay ? maybe a transistor 2n222 ? to boost the 150ma to 250ma? Any help would be great thanks.
Replies:
Posted By: howie ll
Date Posted: April 15, 2013 at 1:52 PM
Do you mean a latching relay or just closing the coil on a standard Bosch/Tycho cube automotive relay?
All 12V coil relays will latch on about 120mA.
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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.
Posted By: howie ll
Date Posted: April 15, 2013 at 1:54 PM
Show me a wiring diagram of what you're trying to do please.
I assume you mean SWITCH when you say latch.
-------------
Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.
Posted By: chicyan
Date Posted: April 15, 2013 at 5:38 PM
hi it's a normal bosch type relay. pin 85 to my 12volt source and pin 86 to gnd, but it does not switch. i'm trying to trig it with a 12volt output on a Rotel amplifier. maybe i can boost it with a lm7812 ? I tried the same relay and setup with stronger 12v source and it works fine. so i'm assuming that i dont have enough miliamps.
Posted By: howie ll
Date Posted: April 15, 2013 at 5:45 PM
It should, I used a Yamaha pro-logic amp many years ago to switch a 4 pole changeover to cut out the TV speakers.
A Bosch type relay will work from about 120mA, if not use a higher impedance PCB type power relay, that should do it, Radio Shack, Mouser etc. etc.
-------------
Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.
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