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Topic: LED...series or parallel? (Read 821 times) previous topic - next topic



I need to wire 25 to 30 RGB LEDs.  Anyone please let me know if and how to do the paraller and/or series circuit?  Thanks in advance.


May 18, 2019, 09:16 pm Last Edit: May 19, 2019, 08:41 am by PaulRB
Series is probably not an option. Post a link to the LEDs so we can confirm that.

In general, if your leds have 6 pins/terminals then series might be an option. If only 4 pins/terminals, then only parallel is the choice.


OK, let's see if we - or indeed you - can makes some sense of this.

What is it you actually want to do?


@Paul....very funnee...I had my day's laugh..!!


I think we're all being serious here (except you).
20watt 6-pin RGB LEDs need other wiring/supply than 20mA 4-pin RGB LEDs.
Tell us more about your project, so we don't waste time advising you the wrong things.


And do not forget to:-
Post a link to the LEDs so we can confirm that.


May 19, 2019, 12:40 pm Last Edit: May 19, 2019, 01:01 pm by Daiwik666
Ok...I ain't too good at explaining, but here goes......  I have 20 LEDs...all RGBs with 4 pins.  I need these to light up as bright as possible.  Is it advisable to go for series with a single resistor...or parallel with one resistor for each LED.  Power is 4 volts and 25 milliamps for the LED.  Now then, for the power, I am drawing it from 220 AC with a step down transformer.  This is about the best I could do for a beginner.  Thanks a million in advance.  Kindly advise.

P.S:  Any good link will help a lot.  I mention "good" because all the stuff I saw on YouTube regarding series/parallel wiring went right over my head.


May 19, 2019, 01:37 pm Last Edit: May 19, 2019, 01:39 pm by PaulRB
I still don't see any link to the LEDs. So I conclude that you are not serious about wanting our help, you only want to waste our time.  Good luck with your project.


For pete's sake..where is this precious link that I have to post to??


OK, the link requested is the Web link for the place from which you bought the LEDs identifying all their specifications.

However, I will work from what you have described, allowing for the lack of information.

Four pin RGB LEDs are either common-cathode or common anode.  This means they cannot be put in series because you need LEDs with separate connections to each internal LED to do so, which would be six pin RGB LEDs.
Like this:

And connected like this:

But it gets back to my question - just what do you want to do?  Are they all to show the same colour with one red driver, one green and one blue?  In which case that diagram gives a hint.


Hi Paul:

Thanks for explaining on the link.  Here it is:  https://www.amazon.in/gp/product/B07NBGBS26/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

As for what I want to do:  I need 20 to 25 LEDs inside each translucent letter on a gator board (for a birthday party) and use a fading program in an Attiny chip.  For example, PAUL.  Four letters in translucent plastic (any other material suggested is welcome also please), each letter is solid and hollow measuring about 8 x 8 inches.  I need around 20 RGB LEDs inside each letter.  Hope this explains my project.  I am trying to figure out your diagram above.  Thought I would reply first. As always, thanks for the response.


May 19, 2019, 08:56 pm Last Edit: May 19, 2019, 08:58 pm by Grumpy_Mike
These are  5mm RGB LED 4 Pin Common Cathode LEDs. So you can not in any way wire them in series.

Therefore they have to be in parallel. Each anode will need its own current limiting resistor. You can apply PWM to the cathode providing you drive this with a FET an Arduino pin will not cut it.

A much simpler way to do this is to cut up lengths of WS2812 LED strip. It will be far cheaper, even if you already have the RGB LEDs. Use them on another project.


A much simpler way to do this is to cut up lengths of WS2812 LED strip. It will be far cheaper, even if you already have the RGB LEDs. Use them on another project.
My sentiments entirely given that you want to use a colour changing code.

Note that each LED consumes up to 60 mA at full white, so you probably want to allow for that, 20 of them may therefore require up to 1.2 Amps, a 5 V "Phone charger" which is readily and cheaply available for each letter could suit quite nicely.  A waste of time configuring an ATtiny; easier and cheaper to use Pro Minis if space is a concern, otherwise Nanos.

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