# Does it matter how I wire it?

#### kirit

Joined Sep 9, 2008
35
Ok, Im continuing my learning/trainer project. I need to find out how to wire a few switches and LEDs. If i have 6 switches, can I power them and ground them in series? With the LEDs I plan on grounding them in series too. Does that matter?

What i plan on doing it taking 6 switches, glueing them next to each other. Taking one wire for the power and one for ground and soldering all the switches with those 2 wires. Than Taking 6 individual wires to the breadboard to carry power when switch is closed. Does it make sense? Or do i have to wire power/ground individually to each switch?

Also can the LED ground be used in series?

#### jpanhalt

Joined Jan 18, 2008
10,525
The simple answer is yes. You can wire 6 switches so each switch supplies a board with one wire when turned on and also lights an LED. I would describe the wiring as being in parallel, not series. The ground would go to the board. Power would go to each switch. You need 8 wires total: 1 for power to the switches, 6 from the switches, and ground to the board. If you want the LEDS on the switches, then you need a ground to the switches too.

Can you provide a drawing of what you plan to do.

John

#### kirit

Joined Sep 9, 2008
35

This is what im trying to get to. Sorry no drawings/schematics yet. basically i want my breadboard to have a power supply (check), have several switches and LEDs.

#### jpanhalt

Joined Jan 18, 2008
10,525
Is this what you are trying to do?

John

#### kirit

Joined Sep 9, 2008
35
Ahhhh, I see where I went wrong in describing what I wanted. The switches will provide power to logic gate circuits, so I can simulate on/off. The output will power (or not) the LEDs.

What I was thinking of doing was run one wire for power out of the breadboard to the switches, same for the ground. Then for the other wire(called common?) I would run that to the breadboard. One for each switch. For the LED I wanted to run one ground from the breadboard ground line and wire all the leds to that. then take 6 individual wires and solder a resistor and wire it to 6 slots on the breadboards so they are independent of each other.

Now if I place a 7400 IC chip on the breadboard, I would wire 2 inputs from the chip to the breadboards slots where 2 of the switches had been wired. the output from the chip would be wired to one of the LED slots. If turn the power on and properly ground and power the chip. I should get the LED to turn on when sw1 and sw2 are off/off, off/on, on/off, but the LED should be off when sw1 and sw2 are on.

I hope i havent muddied the waters more. Im just confused on how to simplify the wiring, without screwing up the amount of power needed to power the chips.

#### kirit

Joined Sep 9, 2008
35
Ok, Ive used my mad paint skills to get this:

This basically shows what I want to do. ignore the blue part, the led legs were a bit long.

#### jpanhalt

Joined Jan 18, 2008
10,525
So, they are SPDT switches and you want a logic hi or lo depending on selection. That works. The switches are in parallel. You can glue the switches together or simply use a ready-made switch.

As for the rest of what you want, it is still not completely clear. Just remember, each LED needs its own resistor, if they are in parallel like the switches, which I suppose is the case.

John

Edit: You can also put a pull-up resistor on each logic line, then use a SPST DIP switch (like in the schematic I posted) to pull each logic low.

Really, if you can post a sketch of what you want to do electronically, it would be quite simple to give you a working schematic.

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