Pulse/Fading Led Circuit PCB design please..

[gameshark888]

Hello,

Can anyone help me build/make the pcb design of this circuit that i saw on youtube(I'm confused when reading schematics) a pot here is used to control the slow fading of the LED (cool!) while others used only resistor (for me pot is better to use). I have basic skills in soldering so it would not be a problem soldering on the PCB and what components are used here? I wanna make one of these for my school project and as 12v dc input. Thanks in advance for the great help guys =]

Video 1: YouTube - Pulse LED circuit

Video 2: YouTube - The world's simplest 555 LED Fader

 

[KJ6EAD]

If you use the circuit as shown on 12V, you will destroy your LED. Take a look at this: .

 

[cent24.3]

Hi,

Of course it's not a typical application of the 555 BUT it should work except that KJ6EAD is right you're going to blow your led.

The best way to NOT blow your led is to insert a resistor (270 Ω for a white led on 12v) between the led anode and the transistor emitter to limit the current through the led. Like this the maximum current in the led will be ≈20mA because the voltage on the base of the transistor will not be greater than 9V (2/3 of 12V).

I add that with 12V power I think the LED will not completely shut off, because the voltage on the emitter of the transistor will be between 8.4V and 3.4V ( this last voltage is more than the led forward voltage). If you want the complete shut off you may insert a 3V zener diode between the led and the previously added resistor.

Finally I'll add a resistor between the pin 3 of the 555 and the potentiometer (let's say 100Ω to limit the current on the 555.

I'm not error free but I hope that will do the job.