49 questions linked to/from How can I efficiently drive an LED?
3k views

### Will using a resistor in series with a LED to control its voltage increase the total energy expenditure? [duplicate]

This might sound like a stupid question, but I want a confirmation. I watched a video on Youtube about using LEDs. Those LEDs required a voltage around 2 volts at 20 mA. In order to power one LED ...
4k views

### Calculate expected voltage around a resistor [duplicate]

It's been a few years since I first studied the Ohm's law at school. Now I'm really getting into electronics, and I must admit a part of it still puzzles me. I know this is kind of a strange question,...
744 views

### Dynamically dimming individual LEDs in a lighting system [duplicate]

I'm planning to build an aquarium lightning system with individually controllable LED's, I don't have much experience with electronics except from the irregular tinkering, but I'm a programmer and I ...
2k views

### How can I decrease a DC voltage without a resistor [duplicate]

I would like to light up a 2 W LED with a 3.7 V power source in the most efficient way possible. The Vf of the LED is 2.4 V. Is there any way I can reduce the voltage to 2.4 V from 3.7 V without using ...
2k views

### How to power led from arduino [duplicate]

I am new to electronics and ohms law is confusing. When I power the led with analogWrite and give it only 3 volts do I have to still use a resistor? When I power the led with 5 volts does it matter ...
268 views

### How do I drive 12 strings of 12 leds each? [duplicate]

I would like to drive 144 leds with a battery power supply. I want to drive all the leds all the time. 12 leds in series on each string. The Led specs are: ...
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### What resistors to use for 60, 8000mcd LEDs, with 4 * 1.5v battery source? [duplicate]

I currently have 60 LEDs in a parallel circuit. I am using 4 1.5v batteries as the source. The LEDs have a forward voltage of 3v-3.4v (8000mcd, wavelength 460nm). My questions are: Can I just use ...
87k views

### Why exactly can't a single resistor be used for many parallel LEDs?

Why can't you use a single resistor for a number of LEDs in parallel instead of one each?
23k views

### Why can't I light a LED with a 1.5 V battery?

The LED I am using requires a higher voltage to light than I have supplied, and as a result, it doesn't light at all. I would expect at least a dim light, but light is not generated. Why this ...
22k views

### Does pulsing an LED at higher current yield greater apparent brightness?

This question implies two assumptions: The frequency of a switched LED driver is high enough that average power, not instantaneous power, should be used to determine maximum drive current. The ...
20k views

### Correct formula for LED current-limiting resistor?

I'm trying to work out what value resistor to use in a LED circuit. The equation I'd use to do this is: $$R = \frac{V_{cc} - V_f}{I_f}$$ Seems logical, and makes complete sense. The answers to the ...
39k views

### Is it OK to put LEDs in parallel? [duplicate]

I wonder if it's a good idea to put LEDs in parallel, as below: I've heard that it might not be because the voltage threshold won't be exactly the same for each LED, so they'll shine all with very ...