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multiple input to one output

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=102993
Printed Date: May 05, 2024 at 5:45 PM


Topic: multiple input to one output

Posted By: necplusultra1
Subject: multiple input to one output
Date Posted: March 12, 2008 at 6:16 AM

greetings,

I have 5 accesory switches. I would like to light up a red led when one of the 5 switches are active. The first switch to be active will light up the red led. Any of the 5 switches can light up the red led.  How can | wire this so that the light switches on when one or more of the 5 switches are on.

regards.




Replies:

Posted By: i am an idiot
Date Posted: March 12, 2008 at 6:41 AM

You will need 5 diodes available at radio shack.  I have no idea what the radio shack part number is but the actual number of the diodes is  1n400X   X being any number from 1 to 7.   You will have to connect 1 diode to each switch.  Connect the anode of the diode to the wire that gets hot when you turn the switch on.  Connect the cathodes of the diodes together, and this will provide you with 12V output anytime any one of the switches are turned on.  If you DO NOT have a 12 Volt LED you will need to install a resistor in series with the LED to keep from burning it up.  A 560 ohm resistor will do the trick.

https://www.the12volt.com/diodes/diodes.asp





Posted By: necplusultra1
Date Posted: March 12, 2008 at 7:31 AM

That's exactly what I was thinking of but what voltage will I obtain if 2, 3 4 or 5 switches are turned on? Will the output still be 12 V?





Posted By: necplusultra1
Date Posted: March 12, 2008 at 8:56 AM

I think what I'm looking for here is a way to limit the output to 12 volts. Either through a resistor or some kind of voltage controller. Another option would be to use relays and mimic a "or gate". Problem is that I am an electronics rookie and I do'n know how to design this kind of circuit. Any input would be appreciated

thanks.





Posted By: KPierson
Date Posted: March 12, 2008 at 10:34 AM

The voltage won't change if you have more then one on, and the resistor will limit the current.



-------------
Kevin Pierson




Posted By: necplusultra1
Date Posted: March 12, 2008 at 12:00 PM

In that case, I'll try the diode and the 560 Ohm resistor

thanks.





Posted By: i am an idiot
Date Posted: March 12, 2008 at 4:35 PM
diodeS 1 per switch




Posted By: necplusultra1
Date Posted: March 12, 2008 at 8:24 PM

Thanks for the help i am an idiot

you were correct from the start,  BTW, that was a typo. I understood the 1 diode per accesory. I tested with 2 switches and this works fine without any resistor . I don't have any resistors on hand right now so I limited my testing to 2 switches. As for the resistor,  I've seen  two 560 ohm resistors: 1/4 watt and 3 watts.  Which do you suggest? The 4 switches are powering my 4 relay coils for fog lights so they\ll be hooked up to probably a 5 or 10 amp connection.

regards.





Posted By: KPierson
Date Posted: March 12, 2008 at 8:48 PM

If it works fine without any resistor then you must have a 12vdc LED, otherwise the LED would have been really bright for about a second and then it wouldn't light any more.

If you don't need a resistor with the two switches you won't need one at all.  The important thing is to use the diodes to keep your isolation between relays.  The resistor is simply to protect the LED from an overcurrent situation.



-------------
Kevin Pierson




Posted By: i am an idiot
Date Posted: March 12, 2008 at 8:59 PM
As Kevin stated above you must have a 12 volt LED.  If in the future you have a low voltage LED that requires a resistor, the 1/4 watt will be fine.





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