Help with simple LED switch project design

[swood]

Hi all,

My son has expressed an interest in electronics (he's 6) as a friend gave him a bag of various 20 switches that have led bulbs in them.

This sort of switch:
http://i01.i.aliimg.com/photo/v7/252501789/Lamp_Rocker_switch_with_light_RS_608.jpg

I have purchased a ABS project box and a bread board and wires, what we want to do is add as many switches to the project box as possible and power them with a 9v battery. We're going to label the switches 'Launc', 'Missiles' 'Smoke Screen' etc.

My question is where should I place the resistors? What size would I need? I want to avoid blowing the LEDs but we would like more than one lit at the same time.

Many thanks
Steven

 

[Supercap2F]

Have a look at this resource.

Dan

 

[BobK]

Lighted switches usually have the resistor built in. If you don't mind sacrificing one of switches, try with no resistor and a multimeter hooked in series to measure current. If it reads around 20mA, it does not need a resistor. If it goes flash and quits, it needs about a 390 Ohm resistor.

Edit: On second thought, maybe you should ignore that advice and just try a 390 Ohm resistor.

Bob

 

[swood]

Thank you both.