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that_guy
23-12-2018, 03:40 PM
I'm on the last step of assembling the myfocuserpro2. I've soldered all the bits except for the 5V led. I've got a WHOLE load of 12v led (that I ordered by accident). I'm having trouble sourcing a 5v wired led (blue and green if possible, although colour is not that important). Does anyone know where I can get a few of these? Also, if I'm not too fussed about whether or not the led is on (or dim), can I use the 12v led in lieu of the 5v? Will the circuit still work? I'd prefer not to make a 5v led using a heap of resistors if possible.

Thanks,
Tony

Wavytone
23-12-2018, 03:49 PM
All it takes is 1 led + 1 resistor...

redbeard
23-12-2018, 04:09 PM
For 5 volts use a normal LED with a 330 ohm resistor. That is generally how it's done. https://learn.sparkfun.com/tutorials/light-emitting-diodes-leds

Beware of blue LED's being very bright in the field, red is better for eyes at night.

Cheers,
Damien.

DarkArts
23-12-2018, 04:51 PM
Jaycar (https://www.jaycar.com.au) has a fairly wide range of LEDs.

that_guy
23-12-2018, 05:21 PM
the 12v LED I have has a forwarding amp of 20mA which means it has has a 600ohm resister in the LED. Using ohms law, would this mean I need a ~430ohm resistor?

E23
23-12-2018, 07:12 PM
Tony, if your LED is actually rated to operate with a 12v source it means it already has a resistor built in or included, probably around 500-600 ohms. All LEDs need a resistor to limit the current to around 20mA. If you are sure that your LEDs already have a resistor bulit in you can still use them with 5v but will be a little less bright. Careful, if there is no resistor in series with your LED you will blow it up applying 5v (or 12v) directly.

Andras

DarkArts
23-12-2018, 07:29 PM
Resistor bias circuits for LEDs:

http://www.resistorguide.com/resistor-for-led/

iborg
24-12-2018, 08:33 AM
Hi


Connect one of your 12V LED's to 5V and see what it looks like.


It may be fine for use at night, as you only want a dim light anyway.


Philip

Exfso
24-12-2018, 12:53 PM
I use a 470ohm resistor for the leds in my light boxes, no issues as yet on 12 volts. One guy wanted the light box to operate with 9volts, just a matter of varying the resistor value.
here is a helpful link: https://www.pcboard.ca/led-dropping-resistor-calculator