Hi im looking for some 5v leds for the front panel of my amp they will light up when a different input is selected they need to be small so i can drill small holes so they can be countersunk with flat tops. I've looked on the web but cant find them. what do you guys use? thanks
LEDs are easily sourced. For instance:
Standard LEDs - Through Hole | Mouser
Are you looking for something in a specific form factor or mounting style?
Standard LEDs - Through Hole | Mouser
Are you looking for something in a specific form factor or mounting style?
Have you a link to what you actually bought ?
To illustrate what happens, when you apply a rising voltage to an LED no current initially flows. When that voltage reaches a certain value (value depends on colour as PRR stated above) then the LED conducts and current flows. It lights. From that point on, any small increase in voltage causes a massive increase in current, massive to the point of destruction.
So we use a series resistor to swamp changes in supply voltage and to set an initial current suitable for our supply voltage and desired brightness.
To illustrate what happens, when you apply a rising voltage to an LED no current initially flows. When that voltage reaches a certain value (value depends on colour as PRR stated above) then the LED conducts and current flows. It lights. From that point on, any small increase in voltage causes a massive increase in current, massive to the point of destruction.
So we use a series resistor to swamp changes in supply voltage and to set an initial current suitable for our supply voltage and desired brightness.
Have you a link to what you actually bought ?
To illustrate what happens, when you apply a rising voltage to an LED no current initially flows. When that voltage reaches a certain value (value depends on colour as PRR stated above) then the LED conducts and current flows. It lights. From that point on, any small increase in voltage causes a massive increase in current, massive to the point of destruction.
So we use a series resistor to swamp changes in supply voltage and to set an initial current suitable for our supply voltage and desired brightness.
Hi these are what i ordered.
3mm 5mm Flat Top LED LEDs RED GREEN BLUE WHITE YELLOW Superbright NEW UK SELLER | eBay
Hi these are what i ordered.
3mm 5mm Flat Top LED LEDs RED GREEN BLUE WHITE YELLOW Superbright NEW UK SELLER | eBay
They aren't 5 volt LED's they need a series resistor.
In case you missed the LARGE RED LETTERS UNDERLINED WARNING repeated TWICE:
IMPORTANT: You should always use a current limiting resisitor when powering an LED, please see my other eBay listing for suitable resistors.
IMPORTANT: You should always use a current limiting resisitor when powering an LED, please see my other eBay listing for suitable resistors.
IMPORTANT: You should always use a current limiting resisitor when powering an LED, please see my other eBay listing for suitable resistors.
IMPORTANT: You should always use a current limiting resisitor when powering an LED, please see my other eBay listing for suitable resistors.
Hi these are what i ordered.
As everyone says, you need a resistor. If these are really high efficiency devices then they will be plenty bright enough on a milliamp or so, maybe less.
What voltage are you going to use to supply them (and their resistor ) ?
If you read the E-Bay advert, the seller has given you the data that you need.
All LEDs have a forward voltage Vf.
Let's say this is 1.3V as an example.
Most LEDs will operate quite happily at 5mA.
If you wish to use this LED at 5V you need to use the following formula.
R = (5v - Vf) / 5mA
R = 3.7 / 0.005
R = 740 Ohms
It is typical to use the closest value available which is 720 Ohms.
Power = I*I*R = 0.005 x 0.005 x 720 = 0.00175W
That is so small that any sized resistor will do the job as long as it is in the order of 720 Ohms.
If the LEDs are wired in parallel, each LED will require its own resistor.
All LEDs have a forward voltage Vf.
Let's say this is 1.3V as an example.
Most LEDs will operate quite happily at 5mA.
If you wish to use this LED at 5V you need to use the following formula.
R = (5v - Vf) / 5mA
R = 3.7 / 0.005
R = 740 Ohms
It is typical to use the closest value available which is 720 Ohms.
Power = I*I*R = 0.005 x 0.005 x 720 = 0.00175W
That is so small that any sized resistor will do the job as long as it is in the order of 720 Ohms.
If the LEDs are wired in parallel, each LED will require its own resistor.
In the real world the LEDs will actually work perfectly well with a current of anything between 5mA and their maximum rating (usually 20mA). 10mA is normally picked as a mid-point value.
The brightness of the LED is not normally controlled through the current. It usually has to be controlled through Duty Cycle - i.e. flashing it. 50% on 50% off equals half as bright.
Just to re-iterate, LEDs cannot be directly paralleled, each one needs it's own resistor.
The more usual solution is to connect the LEDs in series, but with a limiting factor of a 5V supply that gets awkward.
If you connect two LEDs in series, then the VF's can be added together in the following formula.
R = (5V-Vf1-Vf2) / 10mA
So using Vf at 1.3V as before
R = 2.4 / 10 mA = 240 Ohms.
Three LEDs in series
R = (5V-Vf1-Vf2-Vf3) / 10mA
R = 110 Ohms
Four LEDs in series would make Vf higher than the 5V supply and the LEDs might fail to illuminate.
You can of course mix the two solutions.
The brightness of the LED is not normally controlled through the current. It usually has to be controlled through Duty Cycle - i.e. flashing it. 50% on 50% off equals half as bright.
Just to re-iterate, LEDs cannot be directly paralleled, each one needs it's own resistor.
The more usual solution is to connect the LEDs in series, but with a limiting factor of a 5V supply that gets awkward.
If you connect two LEDs in series, then the VF's can be added together in the following formula.
R = (5V-Vf1-Vf2) / 10mA
So using Vf at 1.3V as before
R = 2.4 / 10 mA = 240 Ohms.
Three LEDs in series
R = (5V-Vf1-Vf2-Vf3) / 10mA
R = 110 Ohms
Four LEDs in series would make Vf higher than the 5V supply and the LEDs might fail to illuminate.
You can of course mix the two solutions.
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I use this type of LED (though not from this source) for through front panel. They need a 2mm hole and produce a very neat result.
2mm Lighthouse LED - White, Warm White, Red, Blue, Green, Yellow, Orange | eBay
2mm Lighthouse LED - White, Warm White, Red, Blue, Green, Yellow, Orange | eBay
i like these:
5580501027F Dialight | Optoelektronik | DigiKey
will snap into your front panel from the outside.
5580501027F Dialight | Optoelektronik | DigiKey
will snap into your front panel from the outside.
LED resistor calculators
As people have already said, you need a resistor to current limit the LEDs so they don't die early.
There are bunch of on-line calculators where you enter the color and voltage to compute the resistor value (and wattage needed)-
Current limiting Resistor calculator for leds
LED Series Resistor Calculator | DigiKey Electronics
LED Resistor Calculator - Electrical Engineering & Electronics Tools
While the LEDs can take 20 mA, I dont think they are much dimmer at 10mA or even 5mA is ok most times.
As people have already said, you need a resistor to current limit the LEDs so they don't die early.
There are bunch of on-line calculators where you enter the color and voltage to compute the resistor value (and wattage needed)-
Current limiting Resistor calculator for leds
LED Series Resistor Calculator | DigiKey Electronics
LED Resistor Calculator - Electrical Engineering & Electronics Tools
While the LEDs can take 20 mA, I dont think they are much dimmer at 10mA or even 5mA is ok most times.
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