Switching output of relay

Thread Starter

john2k

Joined Nov 14, 2019
207
I have two relays that i use to power two different lights from the relay output. I want to be able to switch it so that the output from Relay 2 can be moved and to Relay 1 at the click of a switch. So basically switching it makes both outputs run on same relay 1 but switching it off turns it back to normal where relay 2 gives second output. I have no idea what sort of switch will do this. Any suggestions?
 

Thread Starter

john2k

Joined Nov 14, 2019
207
Sounds like a common DPDT switch required?
Just had a quick search of DPDT switch and these switches seem to have 3 positions, OFF in the middle and the two ON's at the bottom and top. But i'm looking for a simple on or off. Off keeps the two outputs from the relays as the are seperate and the ON switches the output from relay 2 to connect to the output from Relay 1 (cutting the output from relay 2 completely). So I have two relays like below with the 87A output individually going to each destination. At the flick of a switch I want to be able to completely disable the output from relay 2 and patch that into the same output as Relay 1 (that way relay 1 provides both outputs)

 

eetech00

Joined Jun 8, 2013
3,209
Just had a quick search of DPDT switch and these switches seem to have 3 positions, OFF in the middle and the two ON's at the bottom and top. But i'm looking for a simple on or off. Off keeps the two outputs from the relays as the are seperate and the ON switches the output from relay 2 to connect to the output from Relay 1 (cutting the output from relay 2 completely). So I have two relays like below with the 87A output individually going to each destination. At the flick of a switch I want to be able to completely disable the output from relay 2 and patch that into the same output as Relay 1 (that way relay 1 provides both outputs)
Like this?


Edit: Modified based on post #161655215374669.png
 
Last edited:

ericgibbs

Joined Jan 29, 2010
15,691
hi John,
Please post the switch type/part number so that we can check the spec'.
Also be aware that Relay 1 contacts will be switching double the current if both lamps are the same wattage rating.
What are the lamp's rated wattage.?
E
 

Thread Starter

john2k

Joined Nov 14, 2019
207
hi John,
Please post the switch type/part number so that we can check the spec'.
Also be aware that Relay 1 contacts will be switching double the current if both lamps are the same wattage rating.
What are the lamp's rated wattage.?
E
I will try and get the spec for the switch. It's very vague just says SPDT ON-ON switch.

Yes relay 1 should be able to cope with both lamps because both are LED's with very minimal current draw.
 

MisterBill2

Joined Jan 23, 2018
12,399
The application seems like itis intended to switch on fog lights when the headlights are switched on. It may be for something else though.
So please give us a bit more description, because automotive applications have a number of differences from other applications.
 

Thread Starter

john2k

Joined Nov 14, 2019
207
The application seems like itis intended to switch on fog lights when the headlights are switched on. It may be for something else though.
So please give us a bit more description, because automotive applications have a number of differences from other applications.
The application is to be able to turn rear LEDs on during the day and operate as daytime lights. Relay 1 currently provides power to the front led that turns off when parking lights turn on. So I by powering the rear LEDs from the relay1, it will operate the rears like the front. And when I want to turn off the feature switching it back to go from relay 2 puts it back to original function
 

MisterBill2

Joined Jan 23, 2018
12,399
The application is to be able to turn rear LEDs on during the day and operate as daytime lights. Relay 1 currently provides power to the front led that turns off when parking lights turn on. So I by powering the rear LEDs from the relay1, it will operate the rears like the front. And when I want to turn off the feature switching it back to go from relay 2 puts it back to original function
That makes a lot more sense.
 

MisterBill2

Joined Jan 23, 2018
12,399
Just had a quick search of DPDT switch and these switches seem to have 3 positions, OFF in the middle and the two ON's at the bottom and top. But i'm looking for a simple on or off. Off keeps the two outputs from the relays as the are seperate and the ON switches the output from relay 2 to connect to the output from Relay 1 (cutting the output from relay 2 completely). So I have two relays like below with the 87A output individually going to each destination. At the flick of a switch I want to be able to completely disable the output from relay 2 and patch that into the same output as Relay 1 (that way relay 1 provides both outputs)

Two position switches, WITHOUT a center off position, are also available, but not in all styles and arrangements. So the switch you need for that function may not be available from a local seller of electrical supplies. Bu they are rather common and would work exactly as you seek.
 

Thread Starter

john2k

Joined Nov 14, 2019
207
If the mini switch is rated at 3A 250VAC, does that mean on 12VDC it technically should be able handle higher than 3A? Although combined both my LEDs are probably less than that
 

ericgibbs

Joined Jan 29, 2010
15,691
hi john.
For the same current rating, the dc voltage rating on a switch will generally be much lower than its ac voltage rating. For example, a switch rated for 15 A at 250 Vac will only be rated for 15 A at 12 Vdc. The only difference is whether you are dealing with ac or dc.

https://www.electronicdesign.com/te...ng-the-right-switch-know-your-ac-from-your-dc


Look here John.

https://www.12voltplanet.co.uk/on-off-on-toggle-switch-10-amps-at-12-volts.html


https://www.google.com/search?client=firefox-b-d&q=12V+10amp+toggle+switch
 
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