New questions re heated bed thread

[speedre9]

Well I'm sure the PID/SSR will do what I need when I have the safe wiring diagram, but in the mean time I have this question burning me.
I have seen many images of MK type heat plates with two LED's and one resistor wired to them. There are spots on the plate itself for soldering them in, but.
In all my research, I haven't seen mention of the values of the resistor, or, of the LED's. And, do I need them if I'm using the PID / SSR combination?? :nuts:

 

[Tony Wells]

Resistors are used in LED circuits to limit the current flowing through the LED. The exact value depends on the voltage you are running, and the voltage dropped across the LED, and how much current you want, or can take, through the LED.

Here is a handy calculator to help determine the value of the resistor required.

http://www.pcboard.ca/kits/led_notes/

 

[speedre9]

I have found that those LED's and the resistor are optional and not essential to safe operations of the heated bed.