My personal convention is Vcc is the + side of the power supply, ground is the negative.
Most 555 chips also use the Vcc convention.
As to the experiments, try using 3 LEDs in series along with a 8.2Ω or 10Ω ¼W resistor, then see how much current is used with the 12VDC power supply. It should be in the ball part. Use the resistor to measure the current, and use the number to adjust the resistors you will need. Just in case keep the duration short as possible.
With 3 LEDs per chain there will be 7 chains, this will work out to approximately 1.05A, the power supply will barely work for this mode. If you were using 2 LEDs per chain the resistor would be around 33Ω 1W, and it would draw 1.5A, overloading the power supply.
The problem using 3 LEDs per chain and a small resistor is stability. It isn't very good, and predictability is another issue. Basically you need to try it out on several sets of LEDs (without the dimmer) and see how close it comes for you.
Most 555 chips also use the Vcc convention.
As to the experiments, try using 3 LEDs in series along with a 8.2Ω or 10Ω ¼W resistor, then see how much current is used with the 12VDC power supply. It should be in the ball part. Use the resistor to measure the current, and use the number to adjust the resistors you will need. Just in case keep the duration short as possible.
With 3 LEDs per chain there will be 7 chains, this will work out to approximately 1.05A, the power supply will barely work for this mode. If you were using 2 LEDs per chain the resistor would be around 33Ω 1W, and it would draw 1.5A, overloading the power supply.
The problem using 3 LEDs per chain and a small resistor is stability. It isn't very good, and predictability is another issue. Basically you need to try it out on several sets of LEDs (without the dimmer) and see how close it comes for you.
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