PARRALLEL LOAD LED & RESISTOR

Components & Accessories LEDs
1

Hello everyone

I’ve been tinkering with some hobby electronics projects at home, mostly succesful. I didn’t have an electronics engineering background so often I learn on new topics. I thought that I had enough experience with connecting LED’s but I’m having problems with a new project… In this project I have a couple of water valves (both motorized ball valves and solenoids). To indicate which valves are getting power I added an LED with a resistor in parallel to the valves. The valves run on DC12v.

[My Mercy

The led burns fine with no solenoid valve in the circuit. When a valve is added the resistor gets very hot and burn up or the led burns up. I have no idea why this happens. I can’t understand why the current flow increases to the led as the circuit is parallel. I’m guessing that I’m missing something fundamental to my understanding of electronics. On a more important note how can this be prevented?

The solenoid draws 0.33 A / 4 Watts

The power supply can supply 12V / 5 A, I do expect some voltage drop in the circuit ~ 1 V due to cable length.](https://www.mymercy.me/)

2

A solenoid has an electric coil. When power is removed it can generate a short BUT high voltage spike which can cause your issue. Make sure there is a flyback diode in place ( e.g. see https://en.wikipedia.org/wiki/Flyback_diode)

3

paulvha:
A solenoid has an electric coil. When power is removed it can generate a short BUT high voltage spike which can cause your issue. Make sure there is a flyback diode in place ( e.g. see https://en.wikipedia.org/wiki/Flyback_diode)

Thank you for sharing the solution, I will try to figure it out for more.

[MyMercy](https://www.mymercy.me/)