How Much Voltage and Current Do I Need for 8 LEDs in Series and Parallel?

[ChrisToffer]

If i have a LED which drops 3V, and 30mA through each LED and i need 8 LED in series.. does it mean that i need a total of 24V and 30mA from power supply or less?
And if i use the same circuit in parallel, does it mean i will use 3V but much more current like 0.24A?? or least current?

 

[psparky]

For your series circuit, I believe you would need at least 24 volts at 30 ma.

That's 720 mwatts from your source.

For parallel, 3 volts will work with 240 ma coming from source, yet each branch will get it's 30ma.

That's also 720 mwatts from your source.

 

[mfb]

If i have a LED which drops 3V, and 30mA through each LED and i need 8 LED in series.. does it mean that i need a total of 24V and 30mA from power supply or less?

Why less? You'll need 24V and 30mA. It is safer to use a voltage a bit above 24V together with a suitable resistor in series.

And if i use the same circuit in parallel, does it mean i will use 3V but much more current like 0.24A?? or least current?

8*30mA of course. The same advice: use a resistor in series.

 

[Baluncore]

LED current is highly sensitive to applied voltage and temperature.
Each parallel path will require a resistor to stabilise the current in that path.

Consider a 12.00 volt DC supply for 8 LEDs.
4 LEDs in series would give no control of current at varying temperatures.

3 LEDs and a 100 ohm resistor in each series chain would stabilise the current at 30 mA. One of the three chains will need an extra 100 ohm resistor or a hidden LED to make 8 visible LEDs total.

2 LEDs with 200 ohms in series will be less efficient than 3 LEDs with 100 ohms.

 

[alphy]

In order to determine the total voltage and current needed from the power supply, we need to first understand the behavior of LEDs in series and parallel circuits.

In a series circuit, the total voltage required is the sum of the individual voltages of each component. This means that in your case, with 8 LEDs in series, the total voltage required would be 24V (8 x 3V). However, the current remains the same throughout the circuit, so the total current needed from the power supply would still be 30mA.

In a parallel circuit, the total current is the sum of the individual currents of each component. This means that if you have 8 LEDs in parallel, the total current needed would be 240mA (8 x 30mA). The voltage needed would still be 3V, as each LED still requires 3V to operate.

In terms of which circuit would require less current from the power supply, it would depend on the specific components used. In general, a parallel circuit would require more current, but it may also be more efficient as the current is distributed among multiple components.

Additionally, it is important to note that the total voltage and current needed from the power supply will also depend on the voltage and current capabilities of the power supply itself. It is important to ensure that the power supply can provide enough voltage and current for the circuit to function properly.

In summary, when designing a circuit with LEDs, it is important to consider the behavior of LEDs in series and parallel circuits in order to determine the total voltage and current needed from the power supply.