circuit-designkirchhoffs-lawsledresistors
I was recently confused on where the resistor would go on the circuit. I then learned that it didn't matter. Is there a standardized sequence for the placement of resistors? For example,
battery -> resistor -> led
or
battery -> led -> resistor
I know it doesn't make a difference, I just want to know which one is more common. Thanks!
Maybe you used a 5-band resistor like here: -
Or maybe it was a four band without tolerance?
Green, green, brown, gold would give you 55.1 ohms and this would fry the resistor/LED with about 120mA.
OR maybe it's an inductor!!
Yes you can, however it will subject the 'off' LEDs to reverse bias. If you are using a 5V supply or less, worst case will only be a few volts, which virtually all LEDS are rated for.
If you are using a CD4017 on an 18V supply, you will be exceeding the reverse rating of most LEDs-- typically 5V or so-- (but it might still work).
Each 'off' LED sees the output drive voltage (typically close to the supply voltage) minus the forward voltage of the 'on' LED (typically 2-3V, or maybe 1V if the LED is an IR type).
Best Answer
With 1 LED and 1 current limiting resistor it does not matter and there is no convention. Not for schematics (where there are a lot of conventions for readability). And not for PCB layout where practicality, space and good engineering normally win out.
That said, in some cases the resistor needs to go between the power supply and LED (such as common cathode displays):
And in others between the LED and ground (such as common anode displays):
But these are examples where the design (arrangement of LEDs) dictates the placement.