How can I add a candle flicker LED to my static LED circuit?

[pnutttz]

Hi everyone.

I should start by saying I'm not sure I'm in the right place here (this isn't a householder issue - I'm making a Ghostbusters backpack for my son!), and that I have no knowledge at all of electrical circuits.

I have a simple circuit with 3aaa batteries powering a string of static LEDs of differing colours (in series, if I've got my lingo correct). I want to add a candle flicker LED to the circuit. It can be added to the end of the 'chain' if that'd work best, doesn't really matter.

Naively, I thought if I just spurred off from one of the static LEDS it'd work without affecting the other LEDs because their power would be unaffected. But of course that hasn't worked (regardless of where in the series I add it), and it makes all the other LEDs flicker too!

What do I need to do to stop that happening please?

I'd be really grateful for any (very cheap!) solutions.

Thanks in advance.
Mark

 

[DPG]

Take the supply to your flicker LED from the battery output. So you have your flicker LED and your normal LEDs both connected to the positive and negative if the battery.

Note, what supply voltage does your flicker LED require?

 

[pnutttz]

Take the supply to your flicker LED from the battery output. So you have your flicker LED and your normal LEDs both connected to the positive and negative if the battery.

Note, what supply voltage does your flicker LED require?

Thanks very much for the reply. Yes, the LEDs just run straight off the battery pack. The flicker LED I bought gives these specs:

• Forward current: 20mA typical
• Forward voltage: 2-3V

Does that help?

Thanks again for helping me

 

[pnutttz]

Take the supply to your flicker LED from the battery output. So you have your flicker LED and your normal LEDs both connected to the positive and negative if the battery.

Note, what supply voltage does your flicker LED require?

Oh, just realised you were telling me to take the flicker LEDs straight off the battery!! Thanks, I'll try that!

 

[DPG]

Oh, just realised you were telling me to take the flicker LEDs straight off the battery!! Thanks, I'll try that!

Careful - you will probably need a current limiting resistor.

 

[pnutttz]

Careful - you will probably need a current limiting resistor.

So, tried hooking the flicker LEDs direct to the battery pack and the same still happens. They are much bigger LEDs than the others in the circuit, so wonder if that's the issue? Would the current limiting resistor you mention fix that? If so, are you able to suggest what I should use based on the info I've provided? Unfortunately I have no information on the voltage of the other LEDs as they were cannibalised from a Lego lighting set we had knocking around. They're like those 'micro lights' strings you can buy attached to 3xAAA battery packs though, if that's any sort of guide.

Thanks again - as I'm sure is clear, I have no idea what I'm doing

 

[DPG]

So, tried hooking the flicker LEDs direct to the battery pack and the same still happens. They are much bigger LEDs than the others in the circuit, so wonder if that's the issue? Would the current limiting resistor you mention fix that? If so, are you able to suggest what I should use based on the info I've provided? Unfortunately I have no information on the voltage of the other LEDs as they were cannibalised from a Lego lighting set we had knocking around. They're like those 'micro lights' strings you can buy attached to 3xAAA battery packs though, if that's any sort of guide.

Thanks again - as I'm sure is clear, I have no idea what I'm doing

I would definitely try a resistor. Something along the lines of 47 Ohms.

I'm guessing a bit though. Have you got a link to the flicker LED that you bought?

 

[pnutttz]

I would definitely try a resistor. Something along the lines of 47 Ohms.

I'm guessing a bit though. Have you got a link to the flicker LED that you bought?

Thanks! So if I wire the flicker LEDs straight to the battery terminals, where in the circuit would I install the resistor? On the positive feed wire leading to (but before it reaches) the other LEDs?
This is the flicker LED I bought: Flickering Candle Effect 5mm LED White Red Blue Green Yellow | eBay - https://www.ebay.co.uk/itm/261586968625?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=YRTmJau9QrW&sssrc=4429486&ssuid=Tz0GU5xaTuW&var=&widget_ver=artemis&media=COPY

Thanks again

 

[mainline]

20ma led at 3.3 v is around 68ohm resistor

 

[DPG]

20ma led at 3.3 v is around 68ohm resistor

Not a bad guess then!

 

[pnutttz]

Not a bad guess then!

Thanks, and @mainline. Where should I be installing that resistor within the circuit to stop the flickering of the static LEDs would you suggest?

 

[DPG]

Thanks, and @mainline. Where should I be installing that resistor within the circuit to stop the flickering of the static LEDs would you suggest?

In series with the flicker LED.

 

[pnutttz]

In series with the flicker LED.

Thanks. Dumb question, but do I put it on the positive wire or the negative one? And before or after the LED? Or does none of that matter?

And, last question (I promise!!) - would this do the trick? https://www.ebay.co.uk/itm/31375869...ar=612530592491&widget_ver=artemis&media=COPY

 

[DPG]

Thanks. Dumb question, but do I put it on the positive wire or the negative one? And before or after the LED? Or does none of that matter?

And, last question (I promise!!) - would this do the trick? https://www.ebay.co.uk/itm/31375869...ar=612530592491&widget_ver=artemis&media=COPY

Doesn't really matter but normally between battery positive and the LED.

Those resistor types would be fine yes.

I'd still like to see this flicker LED though to make sure we are on the right lines. Do you have a link to it?

 

[pnutttz]

Doesn't really matter but normally between battery positive and the LED.

Those resistor types would be fine yes.

I'd still like to see this flicker LED though to make sure we are on the right lines. Do you have a link to it?

Sorry, thought I'd posted one - it's this (actually 2 of them):

Flickering Candle Effect 5mm LED White Red Blue Green Yellow | eBay

Flickering candle effect. Flickering 5mm LED with a clear lens and high luminosity output suitable for PCB and through hole applications, including illuminating signs, signals, indicators, toys etc. Excellent weather resistance.

www.ebay.co.uk

And thanks again.

 

[DPG]

Sorry, thought I'd posted one - it's this (actually 2 of them):

Flickering Candle Effect 5mm LED White Red Blue Green Yellow | eBay

Flickering candle effect. Flickering 5mm LED with a clear lens and high luminosity output suitable for PCB and through hole applications, including illuminating signs, signals, indicators, toys etc. Excellent weather resistance.

www.ebay.co.uk

And thanks again.

Thanks. I reckon you'll be fine with the resistor in place, but let us know.

 

[pnutttz]

Thanks. I reckon you'll be fine with the resistor in place, but let us know.

I will. Thanks so much for the help - always really nice to find people so happy to help out others

 

[littlespark]

you canniblised a Lego set??!!

You get no help from me!!!!

 

[pnutttz]

you canniblised a Lego set??!!

You get no help from me!!!!

Haha! It's an aftermarket

you canniblised a Lego set??!!

You get no help from me!!!!

Haha, it's an aftermarket set of lights I bought for some of my son's Lego but they sent the wrong ones and let me keep them instead of returning them! Doing a good job of lighting up a proton pack and neutrona wand though

 

[pnutttz]

Thanks. I reckon you'll be fine with the resistor in place, but let us know.

Thanks for the help everyone. I wired the flicker LEDs direct to the battery, and added the resistor in series on the positive feed just before the LED. Still got a bit of flicker on the static LEDs so added a second resistor on the negative feed after the flicker LED and now all works well. Wouldn't have had a clue how to sort any of that without the help given here, so thanks again.

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