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I've searched and searched for this but I can't find an answer and when I find something that looks like an answer I don't understand it. I'm very, very new to this, I can basically pick the correct resistor for an LED and wire it all up. I use electronics in model making. I'm aiming to control 3 arduinos with switches on the same circuit. I'm fine with the arduino aspect for simplicity I'll just pretend I want to control LEDs.

Currently I have two leds connected to two SPDT toggle switches and I think they are wired correctly however I can't individually control the leds. I have to have both switches set to on for both LEDs to come on, I can't have one off and one on. I don't really understand the diagrams I see on this site so I'll draw a very crude diagram of what I have wired up.

enter image description here

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  • \$\begingroup\$ The way you've drawn that you will short out the battery if either switch is switched to the right. \$\endgroup\$
    – Transistor
    May 27, 2018 at 20:51
  • \$\begingroup\$ How should I have wired it then? I just wired the three prongs on the switches based on googling how to wire SPDT switch. \$\endgroup\$
    – Bruce Leckenby
    May 27, 2018 at 20:55
  • \$\begingroup\$ Are you saying (just to make sure I understand your problem) that you don't know how to read electrical schematics? That's something that might be worth a question of its own; if you're at all interested in electronics it's very important to learn! \$\endgroup\$
    – Hearth
    May 27, 2018 at 21:05
  • \$\begingroup\$ Hi, I understand them to a very limited extent. I mostly use electronics to make my models light up so most of time all I really need to to know is how to program an arduino and use the correct resistor, both of which I'm fine with. I've ran into a few problems already by not knowing how to read schematics so you're probably right, will definitely need to learn it! \$\endgroup\$
    – Bruce Leckenby
    May 27, 2018 at 21:09

1 Answer 1

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I have to have both switches set to on for both LEDs to come on, I can't have one off and one on.

The reason is that when one switch is OFF you are shorting out the supply.

schematic

simulate this circuit – Schematic created using CircuitLab

Figure 1. The circuit on the left is what you have drawn. The circuit on the right is what you want.

I just wired the three prongs on the switches based on googling how to wire SPDT switch.

You don't have to use every terminal. Remove the red wires on my Figure 1.

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  • \$\begingroup\$ Thank you so much! That was a great help and worked a treat! \$\endgroup\$
    – Bruce Leckenby
    May 27, 2018 at 21:06
  • \$\begingroup\$ OK. You can accept the answer to mark it solved. \$\endgroup\$
    – Transistor
    May 27, 2018 at 21:11
  • \$\begingroup\$ We know that diodes shall be driven by current since they respond differently to voltage. My question is how to drive them in terms of current and in the same time provide min voltage to durn them ON. Example circuit would be more then appreciate. \$\endgroup\$
    – DannyS
    Jun 3, 2018 at 21:30
  • \$\begingroup\$ @DannyS: You have been around long enough to know that you don't ask new questions in the comments. Your question isn't even related to this one. \$\endgroup\$
    – Transistor
    Jun 3, 2018 at 21:32
  • \$\begingroup\$ Actually it is related although it may sound like a new question. The problem with the circuit in your answer is current thru each diode may be different. \$\endgroup\$
    – DannyS
    Jun 3, 2018 at 21:37

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