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???
08/04/09 13:32
Modified:
  08/04/09 13:41
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 		 #168136 - Relays Suggestions
Responding to: ???'s previous message
about this option
A) 1 Relay per device. (p89v51 -> ULN2003 -> 1-device/output)
you may consider to install NOT gates between p89V51 and ULN2003 like the 74HC04 to overcome the HIGH state of the MCU pins during the RESET state.

If you use Relays at higher voltage eg 12V or 24V the current will be much less.

Have a look at these links to get an idea how to control a TRIAC by an MCU

51LPC microcontrollers and three-quadrant triacs Leaflet
http://www.nxp.com/acrobat/applicationnotes/MCU_51LPC_3QUADRANTTRIACS.pdf

Vacuum cleaner with Philips P89LPC901
http://www.nxp.com/acrobat/applicationnotes/AN10496_1.pdf

Also this [edited]
AN467_1 Philips 51LPC-Microcontrollers & Triacs easily connected
http://www.nxp.com/acrobat_download/applicationnotes/AN467_1.pdf

googling you will find many more

K.L.Angelis

List of 44 messages in thread
TopicAuthorDate
Mechnical Relay or Triac            01/01/70 00:00      
   Relays Or Triacs            01/01/70 00:00      
      Isolation            01/01/70 00:00      
      Relay or Triac            01/01/70 00:00      
         Pull-in vs hold current?            01/01/70 00:00      
         Relays Suggestions            01/01/70 00:00      
      Agree            01/01/70 00:00      
         optotriac            01/01/70 00:00      
            Relay Vs Triac            01/01/70 00:00      
               multimeter is reading 'hold' current?            01/01/70 00:00      
               a simple "kick and hold" circuit            01/01/70 00:00      
                  RE: a simple "kick and hold" circuit            01/01/70 00:00      
                     Thanks            01/01/70 00:00      
                     no            01/01/70 00:00      
                        I see!            01/01/70 00:00      
                     You are absolutely right...            01/01/70 00:00      
                  What are the values of R and C ?            01/01/70 00:00      
                     To be calculated!            01/01/70 00:00      
                     About...            01/01/70 00:00      
               Here are some calculations ..might be helpful            01/01/70 00:00      
                  RE: some calculations            01/01/70 00:00      
                     To Andy            01/01/70 00:00      
                        current measurement            01/01/70 00:00      
                           Schematic            01/01/70 00:00      
                              Re-Drawn Schematic            01/01/70 00:00      
                                 ASCII Art            01/01/70 00:00      
                     Relay supply            01/01/70 00:00      
                  To Kiran            01/01/70 00:00      
               latching relay            01/01/70 00:00      
                  Latching relays are cost effective            01/01/70 00:00      
                     One thing to consider            01/01/70 00:00      
                        latching relay : status updated on bootup            01/01/70 00:00      
                           Ay be a mix will be fine            01/01/70 00:00      
                           I just found a relay which needs lot lesser current            01/01/70 00:00      
                           That's too late!            01/01/70 00:00      
                              My Circuit            01/01/70 00:00      
                                 But didn't you mention...            01/01/70 00:00      
                                    hot... depends            01/01/70 00:00      
                                       Agreed!            01/01/70 00:00      
                                          Thanks ALL.            01/01/70 00:00      
                                       Low voltage drop            01/01/70 00:00      
                                          Good luck!            01/01/70 00:00      
                              random phase?            01/01/70 00:00      
                                 The same what the manufacturer meant...            01/01/70 00:00      

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