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Hal Albach
03/18/06 19:31
Read: 1687 times
Seminole, Florida
USA


 
#112481 - Reed switch problems
Responding to: Suresh R's previous message
Suresh said:

Also,
for once, i just connected the lamp directly to the 12 V through the reed switch (switch is driven by a driver circuit for ON / OFF operation). i could see only the switch getting closed parmanently.
'NO SWITCHING TOOK PLACE'(note: i just saw how the switch reacts, though the low rating was pointed out in the discussion previously..) and i found the contact opens only when the switch is taken out of the coil (in which the switch would be kept to drive the lamp) and when examined the switch seems to be in good condition..


Many years ago I had a similar problem when I tried to use a small reed switch to turn on & off a small tape player motor. Once switched on I lost control of the reed switch. The motor continued to run even though I had disconnected the coil from the circuit. Only when I interrupted the power in the motor circuit did the reed open. Right or wrong, I figured that since the reed is a magnetic material I guessed that the current flowing through the reed switch was generating enough of a magnetic field that held the reed closed, making it act like a SCR. I replaced the reed switch with a more traditional relay (Potter & Brumfield) and the circuit worked as expected.

Hal

List of 57 messages in thread
TopicAuthorDate
inrush current + suitable voltage sour      Suresh R      03/04/06 10:14      
   Inrush current of lamp      Kai Klaas      03/04/06 20:47      
      Current inrush      Hal Albach      03/05/06 06:28      
         NTC?      Jan Waclawek      03/05/06 06:45      
            Soft-start      Kai Klaas      03/05/06 08:00      
               8 reed SW parallely + 21.12A / at 12VDC      Suresh R      03/06/06 05:29      
                  Car battery???      Anders Sandström      03/06/06 05:58      
                  inrush current      Terry Lingle      03/06/06 08:20      
                  totally irrelevant      Erik Malund      03/06/06 08:58      
                  No testing needed, standardly      Kai Klaas      03/06/06 19:46      
                     replies      Suresh R      03/07/06 02:05      
                        Reply to "replies"      Kai Klaas      03/07/06 07:29      
                           the difference between "cheap" and "inex      Erik Malund      03/07/06 07:44      
                           current limit resistor      Suresh R      03/07/06 09:17      
                              are you just grasping for straws?      Erik Malund      03/07/06 09:29      
            NTC, yes      Erik Malund      03/06/06 08:54      
               Filaments      Kai Klaas      03/06/06 18:38      
                  In the days of radios for AC and DC      Erik Malund      03/07/06 06:57      
                     Thanks      Kai Klaas      03/07/06 07:03      
            resistor parallel to Switch!      Suresh R      03/11/06 04:29      
               MOSFET, constant current source?      Kai Klaas      03/11/06 07:04      
                  not for my use      Suresh R      03/11/06 09:24      
                     Ok, but...      Kai Klaas      03/11/06 10:00      
                        but i think      Suresh R      03/11/06 10:25      
                           Relays      Kai Klaas      03/11/06 10:51      
                              yes ofcourse      Suresh R      03/11/06 11:46      
                                 here we go again        Erik Malund      03/13/06 06:57      
                                    Even more!!      Kai Klaas      03/13/06 07:14      
                                       werlcome to the club      Erik Malund      03/13/06 07:18      
                                       reply      Suresh R      03/13/06 10:49      
                                          why did you not say so?      Erik Malund      03/13/06 11:15      
                                          You made a fool of us!        Kai Klaas      03/13/06 18:24      
                                             reply      Suresh R      03/14/06 03:39      
                                                That's no fun!      Kai Klaas      03/14/06 07:06      
                                                   Suresh, I hope you had fun      Erik Malund      03/14/06 07:28      
                                                   reply      Suresh R      03/14/06 10:29      
                                                      yeah 6 days later.      Erik Malund      03/14/06 10:52      
                  Hello Kai,      Suresh R      03/16/06 22:03      
                     Look at here      Kai Klaas      03/17/06 10:56      
                        Thank you very much Kai.      Suresh R      03/18/06 07:40      
                           It just strikes me      Erik Malund      03/18/06 10:20      
                              yes you are right      Suresh R      03/18/06 12:32      
                                 Reed switch problems      Hal Albach      03/18/06 19:31      
                                    Current rating?      Kai Klaas      03/20/06 19:39      
                                       I recall long ago something about a "sti      Erik Malund      03/21/06 06:47      
                                       Reed problem      Hal Albach      03/21/06 07:11      
                                          Glueing together      Kai Klaas      03/21/06 07:35      
                                             Reed problems      Hal Albach      03/21/06 09:14      
                                                reed relayrs      Terry Lingle      03/21/06 14:01      
                           power dissipation calculations?      Suresh R      03/19/06 08:12      
                              bulb voltage drop      Terry Lingle      03/19/06 10:01      
                                 Thanks      Suresh R      03/20/06 02:12      
                                 (.2*bulb resistance      Suresh R      03/24/06 05:36      
                                    The bulb      Terry Lingle      03/24/06 07:06      
                              Constant current during inrush moment      Kai Klaas      03/24/06 07:22      
                                 Thanks a lot Kai      Suresh R      03/24/06 10:12      
         Choke would be huge      Kai Klaas      03/05/06 07:28      

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