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3.3vdc converter

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novice007

New Member
I've got a 5vdc supply and need to get down to 3vdc for a supply to LED, can I use a 5vdc in / 3.3vdc out converter????
 

edeca

Active Member
What are the LEDs you are using? I think you might be misunderstanding how an LED works.

An LED will have a forward voltage drop. You need to choose a resistor that provides the right current (typically 20mA) and drops enough voltage.

So if your supply is 5V, your LED drops 1.2V (typical) and you need 20mA, you get:

R = 3.8 / 0.02
R = 190

So pick something close by from a standard series, e.g. 220Ω.

There aren't really such things as "3v LEDs". You need more data to pick the resistor.
 

novice007

New Member
it's actually an LED illuminator within a push button switch, the contact rating of the switch is 24vdc @ 1A and details the LED as 3vdc @ 10mA.

I've got 5vdc within the circuit courtesy of a 24vdc / 5dcv converter for another component in the circuit,just wondering the best way to supply to the LED.
 

audioguru

Well-Known Member
Most Helpful Member
So if your supply is 5V, your LED drops 1.2V (typical).......
Please be accurate in your statements and examples. Only an IR LED (invisible) has a forward voltage of only 1.2V.
Red LEDs have the lowest voltage for a visible LED at 1.7V to 2.2V.
 

edeca

Active Member
Please be accurate in your statements and examples. Only an IR LED (invisible) has a forward voltage of only 1.2V.
Red LEDs have the lowest voltage for a visible LED at 1.7V to 2.2V.
Sure, point taken.

Original poster, check the following pages:

Light Emitting Diodes (LEDs)
Technical LED Color Chart

And like I said before, post more information about the specific LEDs so I can help you further.
 
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