positive and negative connected wher they are supposed to be.

I think the battery polarity are connected where they are supposed to be.

 

Here is my entry into the Breathing LED contest. Note that in my circuit, unlike the ones posted all over the web, the LED current goes completely to zero.

 

Here is my entry into the Breathing LED contest. Note that in my circuit, unlike the ones posted all over the web, the LED current goes completely to zero.
View attachment 81589

Is it possible to build breathing Led like this, using 555 IC but without a transistor?

 

Is it possible to build breathing Led like this, using 555 IC but without a transistor?

Only by building a two 555 circuit, where one 555 modulates the pwm duty cycle of the other. In the circuit I posted, the transistor is used as a current amplifier to modulate the LED current directly.

 

if that were a built up sircuit, there would be a big problem, the 555 only draws 15 ma max, and outputs 225 ma max. even figuring in the 4.7 k resistor current, thats no where near 9000 amps.

 

Only by building a two 555 circuit, where one 555 modulates the pwm duty cycle of the other. In the circuit I posted, the transistor is used as a current amplifier to modulate the LED current directly.

I can get the LED breathing without transistor but the circuit needs a large capacitor (50000 uF).

 

Here is my entry into the Breathing LED contest. Note that in my circuit, unlike the ones posted all over the web, the LED current goes completely to zero.
View attachment 81589

What is the function of R3?

 

What is the function of R3?

R3 creates the short time when the Red trace is zero (the LED is completely off, passing no current). Without it, the LED dims, but stays on throughout the cycle. My circuit (with the LED in the collector of the transistor) is independent of the Vf of the LED (2V for red, 3.3V for blue or white).

R2 sets the peak LED current; make it smaller, the peak LED current goes up. If you adjust R2, then R3 would also have to be adjusted downward to preserve the R3/R2 ratio.