All Questions
12
questions
1
vote
1
answer
71
views
Most energy efficient way to make a LED blink using a multivibrator [duplicate]
I'm using this LED. I want to make this LED blink at MAX brightness (100 mA) at 1 Hz. I need to use a multivibrator and therefore can't use any IC chips. The circuit is powered by a 3.7V battery with ...
- 11
2
votes
1
answer
292
views
Designing boost converter for a supercapacitor source and LED load
I have a 2.7 V 100 F supercap, that would equal 364.50 J of energy based on E = 1/2CV^2. If my load is a series of 4 LEDs with a stack forward voltage of 12 V and forward current of 3 A that would ...
- 407
0
votes
1
answer
1k
views
Finding the PPF and PPFD using a LED data sheet
I would like to design my own grow lights to grow indoor plants like strawberries, herbs, etc.
But I have a problem that I need some help to work out:
How many LEDs do I need to light up an area of 0....
- 237
1
vote
1
answer
399
views
Is electricity saved by switching off the lights when leaving a room? [closed]
Incandescents are very energy inefficient for sure so they have to be turned off whenever you leave the room. But I have tried to find the answer for CFL lights, some say that it's more efficient to ...
- 19
-3
votes
1
answer
2k
views
Can I use a USA Led Bulb in Europe? [closed]
I am a software engineer working with an IOT company in the states, Right now I am located in Europe for a month and a half, and have some hardware (light bulbs) that I need to use to finish some ...
- 1
0
votes
2
answers
4k
views
How to calculate the energy output (in Joules) from an LED
I need to emit 20J over 5ms onto a target area of 962mm^2 from an LED source. The source as well as the target will reside in a completely encapsulated environment with reflective internal walls such ...
- 177
2
votes
0
answers
415
views
Are common IR LEDs harmful to the eyes?
Is it safe to look at the IR LED clusters on security cameras that are commonly available? They seem to be quite capable of lighting up a distance of 6m. What is their energy density? I'm not sure if ...
- 893
2
votes
2
answers
7k
views
Will rapidly changing cycling an LED through different colors reduce lifespan?
I just purchased an RGB LED mechanical keyboard, where each key has its own color.
I was playing with the settings, and found one I like: each LED under each key rapidly cycles between colors.
It ...
- 123
2
votes
0
answers
665
views
How to light an LED using supercapacitor [duplicate]
I would like to light up a 3W LED from Cree having a forward voltage of 2.9 V at 350 mA. It's maximum drive current is 1 A and gives 300 lumens/m2 output. I am considering lighting up this LED using ...
1
vote
2
answers
2k
views
Replace some LEDs with Diodes [closed]
I have a COTS solar battery charger that has a number of different LEDs identifying the battery level, if its charging, etc. Its going to live in the shed, so 99% of the time no one will see its ...
- 171
1
vote
1
answer
4k
views
How big should battery be to power two strips of led for few hours?
I have an idea for halloween costume for upcoming Halloween. It will involve building two small sets of infinity mirrors. I am completely new to the electrical engineering. The infinity mirrors ...
- 11
2
votes
2
answers
6k
views
Theory behind the "Joule Ringer" circuit
The less-than-critical thinking free energy types are pointing to the "Super Joule Ringer" demonstrations online, where a quick touch with a 9 V battery illuminates an LED for hours.
I see ...
- 149