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I've exhausted a google search and am hopeful expertise on this board can help me with my objective.

My Arcade has LED lighted buttons when the cabinet is on. The LED button lights are powered by a dedicated 12v 3amp power source.

My objective is to install a 12v rocker switch to allow me to turn on/off the power to these LED lights. HOWEVER, my goal is to have the light on the rocker switch illuminate when the switch is in the OFF position, and NOT illuminated when the switch is in the ON position.

I would greatly appreciate guidance if this can be done. If so, does this require a "special" switch, or is it as simple as reversing any of the wires. If it requires a special rocker switch, would you have a URL link where I may purchase one. My google search for "12v LED illuminated when switch is OFF" comes up empty.

Thanks in advance,

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5 Answers 5

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The easiest way is to use dual-throw switch (also known as DPDT, SPDT, or ON-ON) with a independent light input.

Here is one example: http://www.mouser.com/ProductDetail/NKK-Switches/MLW3012-12-RC-1A/

In this case the common is 2, switch toggles between 1 and 3, and lamp is on separate L+ and L- pins. So you will want to connect common to 12V supply, then pin 1 will go to your lights, while pin 3 will go switch's light (L+). L- goes to ground.

If you cannot find ON-ON switches in the style you like, it will be possible to use regular single pole (SPST / ON-OFF) switch by "shorting" back light when the switch is on. However, this method will waste power, so I only recommend it if you cannot find ON-ON switches you like. Let me know if you are interested in that.

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  • \$\begingroup\$ Thank you for your quick response. It's making a bit more sense now. My LED's are 12v and the switch in the link states 120v. However your response helped my search. \$\endgroup\$
    – CRayF
    Jan 26, 2017 at 18:45
  • \$\begingroup\$ Hm? The switch description says "... 12V LAMP RED". The parametric table mentions 250 VAC, 125 VAC and 30 VDC, but these are all contact voltages, not light voltages. But the website may be mistaken -- download datasheet and decode part number to be really sure. \$\endgroup\$
    – theamk
    Jan 26, 2017 at 18:48
  • \$\begingroup\$ Link above is for 120v. I found partdeal.com/… Rating: 25A at 12V DC My source is 12v 3amp... will this be OK? I'm fine with a 2 color switch, Red(when Off)/Green(when On). Would the above switch work? Could I NOT attach anything to the PIN 3. Green light when power fed and Red light when the switch is in the opposite position? Pin 1 – Positive output to cabinet (Green LED on) Pin 3 - Nothing attached (LED illuminates Red) Pin 2 – Positive input from 12V supply Pin 4 – Connects to ground. \$\endgroup\$
    – CRayF
    Jan 26, 2017 at 19:03
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    \$\begingroup\$ Re link in my post: what makes you think it is 120V? Because "120" does not even appear anywhere on the page. The switch supports up to 30V DC / 5A, so your 12V DC / 2A circuit will work just fine (because both numbers are less than maximum). Re partdeal link you found: yes, if you are ok with red off/green on, just get the switch and leave pin 3 empty, this would work great. \$\endgroup\$
    – theamk
    Jan 26, 2017 at 19:52
  • \$\begingroup\$ So sorry, I missed the AC vs DC... still learning. It's all wired and working fine. THANKS Again... \$\endgroup\$
    – CRayF
    Jan 29, 2017 at 13:31
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What you want to do is very easy if you use a SPDT rocker switch. Many will be available that way.

I was going to post a schematic, but I get a message that imgur rejected the image for some reason.

Connect the center of the switch to the 12 V power. Then either side will be powered, depending on how the switch is thrown. The one that is powered when the switch is in the OFF position has a LED and resistor in series. The other is the switched power to run your load.

Schematic added

Imgur seems to be up again, so here is the schematic I tried to post yesterday:

Again, one of the two branches will be powered at any one time, but not both. Rocker switches are easy to find in SPDT configurations. In fact, that's probably the most common.

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Why reinvent the wheel? LED wiring can be independent of switching function.

Latching Push button Red Led ON/OFF Good up to 12V, 3A.

Push-button circuit

  1. LED on all the time or only when switch is on (depending how you wire it)

So instead of wiring LED for NO (Normally Open), we wire it for NC (Normally Closed). LED gets power when switch is OFF. Turn it ON, LED goes off.

schematic

simulate this circuit – Schematic created using CircuitLab

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schematic

simulate this circuit – Schematic created using CircuitLab

A simple possibility

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  • \$\begingroup\$ Um, his load is LEDs. So not ohmic at all, and likely equivalent to hundreds of ohms, which is not "<<1k". \$\endgroup\$
    – theamk
    Jan 26, 2017 at 18:26
  • \$\begingroup\$ Also, while there are panel-mount rockers which expose raw LED, they are very rare (in my experience); much more frequently you get integrated resistor, so D2/R1/D3 most likely cannot be applied \$\endgroup\$
    – theamk
    Jan 26, 2017 at 18:28
  • \$\begingroup\$ @theamk the load is his "His 12V Arcade" The rocker probably uses a 3mm LED or a light pipe with the rated voltage possible being line voltage or as stated on the back , or if automotive style then 12~14V which may need to be dismantled at risk to damage. if there are no separate leads.. anything is possible, but may not be practical. \$\endgroup\$
    – Tony Stewart EE75
    Jan 26, 2017 at 19:06
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I've used this circuit so many countless times before...

enter image description here The diode on the left is to prevent the base current from driving the load. However this poses a problem as due to the voltage drop it's voltage level is not high enough to pull the transistor up and completely shut it off, so we have the other diode in place to set the required voltage to shut off the transistor to something lower than what the diode set the value on the left.

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  • \$\begingroup\$ @AndrewMorton Not for me... \$\endgroup\$
    – Bradman175
    Feb 28, 2017 at 21:09
  • \$\begingroup\$ I am having similar issues with imgur, seems to not like jpegs, png seems to work ok. \$\endgroup\$
    – Trevor_G
    Mar 1, 2017 at 12:25

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