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Jim Granville
03/24/12 19:11
Read: 637 times

#186870 - more than one inductive load here
Responding to: ???'s previous message
Cian Young said:
Yes I agree entirely. The ULN2003a chip in the schematic's purpose is to drive both relays. Within this chip are flywheel diodes to 'take care' of the back emf from the relays however the problem still continues as I type this, so I'm still unable to resolve this.

You have missed that you have more than one inductive load here.

Yes, the ULN2003a manages the relays, but those solenoids will have even more stored energy, which unclamped, will arc the relay, and stress the solenoid insulation.
What current do the solenoids draw ?. Choose a catch diode that can manage that peak value.

List of 12 messages in thread
Interrupts, the 8052 & Solenoids      Cian Young      03/24/12 13:33      
   Freewheeel diodes      Per Westermark      03/24/12 15:00      
      ULN2003a      Cian Young      03/24/12 18:34      
         more than one inductive load here      Jim Granville      03/24/12 19:11      
            Solenoids      Cian Young      03/24/12 19:26      
               diode choices      Jim Granville      03/24/12 19:42      
         Diodes in ULN2003a      Michael Karas      03/25/12 08:21      
         Within this chip      Erik Malund      03/26/12 07:03      
            Do I hear...      Michael Karas      03/26/12 07:07      
   Irish keypad layout!!      Andy Neil      03/25/12 06:27      
   Lack of resistors.      Michael Karas      03/26/12 08:00      
      Success      Cian Young      03/28/12 11:00      

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