LED Lighting

[Ceejoh]

Hi,Im just a fresher as design engineer. While browsing, I read that 330ohms resistor has to be placed parallel across an LED light, can someone tell me if it is necessary and why?

 

[HexHex]

It is to limit the current to the LED
It isn't necessarily 330ohms either, it depends on the supply voltage and voltage drop

 

[static zap]

Got to get ,parallel series definition sorted !
330 ohm in series sounds more likely , or will dissipate 43W at 120V or worst .!!
---
A higher value may be in parallel to prevent , blinking when they are off due to
capacitive pickup !

 

[Ceejoh]

Thankyou @static zap @HexHex

So do resistors have to be kept both parallel and in series..
How do I discern the values of the transistors and is it a mandate for LED Retrofit?? I intend on retrofitting with Type B LEDs and so would bypass the ballasts but the same fixtures.

 

[static zap]

I have no firm value answers , inrush is very dependent on actual device used ,and quantity that are simultaneously switched. (Industrial/factory situ)
Resistors are in-efficient , practical solutions may involve
NTC or PTC devices when you better understand
which problem (Inrush I /nuisance blinking is being solved)
.....
( apologies my answers are for thought /design concept
rather than a practical design)