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Results tagged with led
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user 45281
An LED is a light-emitting diode. Lighting an LED is considered the "Hello world" of a circuit design, and it can be as simple as using a series resistor, or it can get more complicated, involving PWM and multiplexing.
10
votes
Simple circuit for fading an LED out (no MCU)
With a simple RC time constant you can have the LED slowly turn on by charging up a large capacitor. … mu F} = 33.4\:\mathrm{ms} $$
To have more control over the time constant you could use a BJT and do something similar like this:
Now you are free to use a larger R instead of it doubling as the LED …
- 2,393
2
votes
What is the package name of this Through Hole LED?
It is just a radial through-hole style. Here is one of many red ones I found on digikey.
http://www.digikey.com/product-detail/en/LTL-709E/160-1084-ND/153446
- 2,393
1
vote
LED burned on Arduino
The LED blew up because you did not have a current limiting resistor. See here. When you attached 5V across the LED it likely tried to pull amps of current and instantly smoked. … The LED you used was likely rated for 20mA continuous. …
- 2,393
3
votes
"Upside-Down" SMD LED
No drilling is required, the footprint has a hole in it, and the LED is soldered "upside" down.
Here is an example, when soldered down, the LED is actually shining through the hole in the PCB. …
- 2,393
7
votes
Accepted
Where to pull LED: VCC or GND?
If your circuit is like [Vcc --> LED --> resistor --> IO port] the port must be able to sink the current required for your LED. … If your circuit is [IO port --> LED --> resistor --> GND] then your port needs to be able to source the current required for the LED.
One isn't inherently better than the other. …
- 2,393
22
votes
Accepted
Are UV LEDs really dangerous?
To safely work with these LEDs you should get a pair of glasses that block the possible wavelengths the LED can emit, 390 to 405nm ±2.5nm. Examples here. …
- 2,393
2
votes
4
answers
2k
views
Is there a clever way to prevent a window comparator from oscillating?
Datasheet here
It is necessary that only 1 LED is on at a time.
Solution
I have found one solution but I am asking a question here to see if there is a more elegant or clever one (hopefully). …
- 2,393
0
votes
1
answer
276
views
How does this USB capacitive touch light circuit work? You can touch anywhere and it turns o...
Then the output drives a transistor which turns on the LED when you touch. The capacitor on the left is a sensitivity adjustment connected between the electrode input and GND. …
- 2,393