bdesmond is correct in stating that the cable will add its own resistance but you would have to use a fairly long cable run to reduce the
power form a 9V battery. 30’ of 22AWG cable is going to have a total resistance of less than 1ohm (copper cable resistance for 22AWG is 0.0162 ohms per
foot).
Just remember to use (Length x Resistance x 2) to calculate the resistance in your cable (as a 30’ cable is really a 60’ cable as
power has to flow to the
LED and then back to the battery).
To run a
LED from 9V you need to place a 390ohm
resistor in series with the
LED.
There are charts available that will tell you the resistance of copper
wire per
foot or if you have access to a low ohms
meter, then you can measure it yourself. This is the chart that I have:
<table align="center"
border="1" cellspacing="0" cellpadding="6">
<tr><td>
AWG</td><td>Resistance in ohms</td></tr>
<tr><td>10</td><td>0.0010</td></tr>
<tr><td>12</td><td>0.0016</td></tr>
<tr><td>14</td><td>0.0026</td></tr>
<tr><td>16</td><td>0.0040</td></tr>
<tr><td>18</td><td>0.0064</td></tr>
<tr><td>20</td><td>0.0102</td></tr>
<tr><td>22</td><td>0.0162</td></tr>
<tr><td>24</td><td>0.0257</td></tr>
</table>
I would stay away from trying to harness
phantom power are there is a possibility that you could short it and cause damage to your board.
In your first proposal, you were going to attaché the positive (hot) leads to the
switch as well as the negative (
ground). Be careful with switches as it sounds like you may have caused a short. Some switches are dual pole and others are single pole. Dual pole switches are two separate switches in the same package. You will commonly see these used in situations where you want to reverse the
polarity feeding a motor, like in the
power windows, sun roof
etc on your car. Push the
switch one way and the motor turns clockwise, push it the other way and the motor turns anti clockwise. Other uses are where you want to turn off both the Active and
Neutral input on a device. For your purposes, you only need a single pole
switch.
When wiring your ON/OFF/ON
switch, take the positive lead from the battery and solder it to the centre
terminal of the
switch. Next, connect the positive lead for one
LED form one of the remaining terminals and the positive for the second
LED from the remaining
terminal.
Your
switch should look something like this:
Terminal 1: Positive to Red
LED
Terminal 2: Positive from battery
Terminal 3: Positive to Green
LED
This way, when the
switch is in the centre position, neither
LED is illuminated, Push the
switch up (connects 2 and 3) illuminates the Green
LED and pushing the
switch down (connects 1 and 2) illuminates the Red
LED.
If it were me, I would
power it from a
plug in
power pack as it will supply a constant
power supply. You probably have some kicking around home that don’t get used or were left over after the appliance it use to
power or charge was thrown away.
[edit - I have no idea why there is so much space above my table]