Resistor Needed ?

[gordo_tay]

Hey All,

I am making a simple switch board. All of the items I am wiring to it are around 12v or 5v. I have 4 rocker switches, but what I would like to know if I need a resistor to make it when I select the ON position, the LED will turn on. So the LED acts as a status LED practically.

Thanks,

 

[ericgibbs]

Hey All,

I am making a simple switch board. All of the items I am wiring to it are around 12v or 5v. I have 4 rocker switches, but what I would like to know if I need a resistor to make it when I select the ON position, the LED will turn on. So the LED acts as a status LED practically.

Thanks,

hi,
What colour LED's are you using.?
Decide on either 5V or 12V for your supply and we can suggest resistor values.
You must use a series resistor with the LED's

 

[gordo_tay]

I'd be using Blue LED's. One for each rocker switch as a status LED. I think they might be 3.2v. The bigger the voltage of the LED the more it takes away from the actual item hooked up to the switch, is that how it works ? Or since the items I am using are either 12v or 5 and they are coming from a direct power supply, I'd only be using 12v cable and the ground, therefore I could power the LED via the left over 5v ? I am using a simple "molex" or "4-pin" connector to power these.

Thanks again,

 

[Reloadron]

I'd be using Blue LED's. One for each rocker switch as a status LED. I think they might be 3.2v. The bigger the voltage of the LED the more it takes away from the actual item hooked up to the switch, is that how it works ? Or since the items I am using are either 12v or 5 and they are coming from a direct power supply, I'd only be using 12v cable and the ground, therefore I could power the LED via the left over 5v ? I am using a simple "molex" or "4-pin" connector to power these.

Thanks again,

Your LEDs would be configured like the attached drawing. If you are talking about an ATX Form Factor (Home Computer) power supply you don't need to worry about the LEDs using any current from the load to speak of. This link should tell you everything you need to know about LEDs and selecting a series resistor for them. Note that all LEDs vary a little so the forward voltage and required currents may vary a little. Calculate the resistance based on a little less that maximun rated current for the LED to enjoy a long life. If a Blue LED for example is rated at 5 volts and 30 mA use about 4 volts and maybe 15 mA. If the LED seems too bright, increase the resistance, if too dim, decrease the resistance.

As to your Molex I assume you know Yellow is 12 volts and red is 5 volts and the two black are shared common wires.

Ron

 

[gordo_tay]

Yes, I am talking about an ATX Form Factor Power Supply. Thankyou for all your help. I will go and read the link.