Help with figuring out diodes

brickless

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Hello! New poster, new to LEDs so please excuse my ignorance.

Im trying to add LEDs to a handmade card. (For setup, the card has a speaker to play music with a light sensor to activate it.) I want to put some LEDs in the card and have it twinkle randomly, like each diode activates on its own/not paired in series with other diodes. Is that a reasonable thing to try to attempt? I need approx 7 diodes, just like a slow soft on/off in a random pattern if possible. Theyre going to imitate stars. If I cant make them twinkle or flicker or whatever I'll probably just let them be on whenever the card is open but the aesthetic could be stunning if i can make this happen.

Any and all help is greatly appreciated as I'm starting from scratch to figure out how to work these things. If you have a good link for instructions in general creating with LEDs thats useful too as I'm trying to google something I don't quite understand 😅
 

PhotonWrangler

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Hello! New poster, new to LEDs so please excuse my ignorance.

Im trying to add LEDs to a handmade card. (For setup, the card has a speaker to play music with a light sensor to activate it.) I want to put some LEDs in the card and have it twinkle randomly, like each diode activates on its own/not paired in series with other diodes. Is that a reasonable thing to try to attempt? I need approx 7 diodes, just like a slow soft on/off in a random pattern if possible. Theyre going to imitate stars. If I cant make them twinkle or flicker or whatever I'll probably just let them be on whenever the card is open but the aesthetic could be stunning if i can make this happen.

Any and all help is greatly appreciated as I'm starting from scratch to figure out how to work these things. If you have a good link for instructions in general creating with LEDs thats useful too as I'm trying to google something I don't quite understand 😅
There are three ways to do this -

1) The simplest way -
Go to a store that has a large selection of greeting cards with animated LEDs in them. Look for one that has the twinkling pattern that you want and harvest the LEDs and controller from the card.

2) Slightly more involved way -
Buy some LEDs with the "twinkle" chips built into them. They generally run on 3v or 5v. You might be able to find a string of twinkling "fairy lights" at a larger craft store.

3) The most involved way -
Buy a strip of individually addressable LEDs and drive them with a small microcontroller like an arduino. This will take some programming skills. There are plenty of sample scripts out there for pulsing or twinkling LEDs that could be modified to suit your needs.

Good luck!
 

brickless

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There are three ways to do this -

1) The simplest way -
Go to a store that has a large selection of greeting cards with animated LEDs in them. Look for one that has the twinkling pattern that you want and harvest the LEDs and controller from the card.

2) Slightly more involved way -
Buy some LEDs with the "twinkle" chips built into them. They generally run on 3v or 5v. You might be able to find a string of twinkling "fairy lights" at a larger craft store.

3) The most involved way -
Buy a strip of individually addressable LEDs and drive them with a small microcontroller like an arduino. This will take some programming skills. There are plenty of sample scripts out there for pulsing or twinkling LEDs that could be modified to suit your needs.

Good luck!
Thanks for supplying the language to find these products!! Searching generic terms just brings me to christmas lights over and over again. Is this what you mean on the microcontroller?

And to be clear, the LEDs will be the diode with two long wires and they hook up to the controller chip? Or the flat circular ones that have no wires and they expect you to soder everything up? I don't know the difference 😱 i deeply appreciate the help!!!

I have someone who can help with programming a script but neither of us have dealt with the hardware before
 

brickless

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Thanks for supplying the language to find these products!! Searching generic terms just brings me to christmas lights over and over again. Is this what you mean on the microcontroller?

And to be clear, the LEDs will be the diode with two long wires and they hook up to the controller chip? Or the flat circular ones that have no wires and they expect you to soder everything up? I don't know the difference 😱 i deeply appreciate the help!!!

I have someone who can help with programming a script but neither of us have dealt with the hardware before
There are three ways to do this -

1) The simplest way -
Go to a store that has a large selection of greeting cards with animated LEDs in them. Look for one that has the twinkling pattern that you want and harvest the LEDs and controller from the card.

2) Slightly more involved way -
Buy some LEDs with the "twinkle" chips built into them. They generally run on 3v or 5v. You might be able to find a string of twinkling "fairy lights" at a larger craft store.

3) The most involved way -
Buy a strip of individually addressable LEDs and drive them with a small microcontroller like an arduino. This will take some programming skills. There are plenty of sample scripts out there for pulsing or twinkling LEDs that could be modified to suit your needs.

Good luck!
EDGELEC 100pcs 3mm White Flicker Flickering LED Diodes Candle Flicking Lights +100pcs Resistors https://a.co/d/7PvE7pw

Are these the LEDs you mean? If i buy these do i still need a microcontroller?
 

jtr1962

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And to be clear, the LEDs will be the diode with two long wires and they hook up to the controller chip? Or the flat circular ones that have no wires and they expect you to soder everything up? I don't know the difference 😱 i deeply appreciate the help!!!
For this application most likely the flat ones (technically termed surface mount).
I have someone who can help with programming a script but neither of us have dealt with the hardware before
This is worth a read if your friend is going to be programming this:


Basically, with the technique known as "Charlieplexing", you can control n*(n-1) LEDs with n pins. That means a microcontroller with only 10 I/Os can control 90 LEDs. This might come in handy if you want to make an elaborate star pattern.

I tried it once a while back to control 8 7-segment displays (64 LEDs if you count the decimal point). It worked. I only needed 9 pins instead of the 16 I would need with the usual multiplexing (or 64 pins if I directly drove each LED segment).
 

brickless

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For this application most likely the flat ones (technically termed surface mount).

This is worth a read if your friend is going to be programming this:


Basically, with the technique known as "Charlieplexing", you can control n*(n-1) LEDs with n pins. That means a microcontroller with only 10 I/Os can control 90 LEDs. This might come in handy if you want to make an elaborate star pattern.

I tried it once a while back to control 8 7-segment displays (64 LEDs if you count the decimal point). It worked. I only needed 9 pins instead of the 16 I would need with the usual multiplexing (or 64 pins if I directly drove each LED segment).
Thank you!!!
 

PhotonWrangler

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And to be clear, the LEDs will be the diode with two long wires and they hook up to the controller chip? Or the flat circular ones that have no wires and they expect you to soder everything up? I don't know the difference 😱 i deeply appreciate the help!!!

The ones with the long wires are called "thru hole" LEDs because the wire leads are meant to be pushed thru the holes on a printed circuit board and soldered from the underside. The flat ones with no visible wires are called surface mount LEDs or SMT LEDs for short. They have contacts on the sides or bottom of the package that are meant to be soldered to the circuit board on the top side.

Also this is a great source for LED blinky things as well as tutorials.
 

Dave_H

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For a couple of dollars, you could start with a small string of 10-20 "microdot" LEDs which run from 3v (typically 2AA). You can find these at dollar stores. At that price, they will usually not flash or flicker; they are "dumb" LEDs. Typical colours are white, multi-colour (usually closer to Christmas), have seen orange and purple for Hallowe'en.

If your card runs from 3v (Lithium coin cell, or 2 button cells) you could wire the string to it (disconnect battery holder). You may or may not need a series resistor, depending on the string. Number of LEDs can be trimmed.

For a bit more money, some strings have a "controller" on a small PCB, which may be a timer, or flash them all on/off at the same time; still not quite what you wanted, I realize.

There may be strings out there made up of individual self-flashing LEDs which would be random, closer to what you want.


Dave
Hello! New poster, new to LEDs so please excuse my ignorance.

Im trying to add LEDs to a handmade card. (For setup, the card has a speaker to play music with a light sensor to activate it.) I want to put some LEDs in the card and have it twinkle randomly, like each diode activates on its own/not paired in series with other diodes. Is that a reasonable thing to try to attempt? I need approx 7 diodes, just like a slow soft on/off in a random pattern if possible. Theyre going to imitate stars. If I cant make them twinkle or flicker or whatever I'll probably just let them be on whenever the card is open but the aesthetic could be stunning if i can make this happen.

Any and all help is greatly appreciated as I'm starting from scratch to figure out how to work these things. If you have a good link for instructions in general creating with LEDs thats useful too as I'm trying to google something I don't quite understand 😅
 
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Dave_H

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Also:

How big is the card, and what is powering it (or could be within size constraints)?

What is your budget for cost and time; and how much complexity you want to handle, and time to wire it up? (and development time if any).

Individual control of RGB LEDs is possible, which use daisy-chain wiring, but it may be overkill in a number of ways.

I scoped out some PIC microcontroller projects online several years ago. I bet there is something like this out there. You'd need to find the right device, and have a method to program it.

Dave
 

Dave_H

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Here is another idea. I have not tried it out. The cost and complexity are pretty low.

Some small solar garden lights have "torch" flickering circuit which sequences up to 6-10 (amber or orange) LEDs in a random-ism pattern. Dollar Tree used to (may still) sell one; I have one in the back yard still operating. It runs from single 1.25v cell, would probably work using an alkaline button cell for a short time.

If you can find such light, you might adapt it. Remove the long thin PCB. Bypass/remove existing LEDs, and connect to ones from a micro-dot string, or any other suitable arrangement. Colour may matter as white or blue LEDs have higher vf than orange/amber; could be tried.



Dave
 

Dave_H

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Another option: 3-LED "pumpkin flasher" light from the dollar store. I've seen them in orange, white, or multi-colour. You could double or triple-up your LEDs in parallel. These run on 3v(2xAA)
or 4.5v (3xAAA). The 3-cell might operate as low as 3v at lower output.

This RGY/2AAA (top removed) is from Dollar Tree. The PCB stripped down of LEDs and switch could easily fit inside a card. It sequences three LEDs. Doubling or tripling up gives 6-9 LEDs, though not completely independent.

Dave
 

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Dave_H

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I've just done up a neat little project using a 3-LED "pumpkin flasher" and a 30-LED string of orange "microdot" LEDs. Cost was around $5, and it took a few hours to figure out and construct.

The 3xAAA flasher sequences 5mm R/G/B LEDs in a combined fast/slow flash/fade sequence. Some flashers are 2xAAA. Patterns will vary, you pretty much have to but one and try it.

LED string was disconnected from its 2AA battery holder and cut into three strings. Wires were lightly scraped (Xacto knife) and tinned with soldering iron.

Flasher was disassembled, LEDs were desoldered from PCB, with care as PCB damage can occur. A hairline crack in copper trace did occur, which was worked around. After verifying each string polarity with clip leads, each string was soldered to PCB pads in place of each original LED.

The effect is quite pleasing. Strings can be spread out, or intermingled, even inside a jar. A smaller version could fit in a greeting card. I confirmed that the 3AAA circuit works OK on a CR2032 (3v) cell and slightly lower brightness.

Different colours (white, blue, purple etc.) could be used, or combined. Dollar Tree sells strings but typically limited to 10 LEDs. I found 20-30 strings at other discount stores.


Dave



LED_flasher_orange_3_string.JPG

LED_flasher_3_strings.JPG
 
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Dave_H

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I stuffed the orange LED strings into a clear glass jar, neat effect, at times looks like a cloud of orange fireflies!

BTW is OP still around, appears to be MIA?

Dave
 

Dave_H

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Neat effect. I'll bet it would be even cooler with frosted glass.
By sanding outside of a plastic jar, effect was to blur the otherwise sharp points of small LEDs. Interesting either way.

I'm working on a small circuit using a couple of low-cost older (40 years or so) CMOS ICs, which will "pseudo-randomly" flash up to 8 LEDs.


Dave
 

Got Lumens?

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It's the ideas and accomplishments posted here that keep me coming back for more.
Hope the OP is still around and revists.
 

Dave_H

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I'm working on a small circuit using a couple of low-cost older (40 years or so) CMOS ICs, which will "pseudo-randomly" flash up to 8 LEDs.


Dave
Aim of my exercise was to come up with a simple circuit using no more than two common (14-16 pin) chips, no micro-controllers or firmware. Biggest challenge would be wiring up on something which would fit into a card.

First circuit using a shift register with feedback works fairly well, but not optimal. It can drive up to 8 LEDs. Pattern is definitely not random, more "pseudo-random-ish", which would probably work for the OP's project.

Different circuit uses two 4-bit binary counters running at different speeds with LEDs cross-connected between them. It could drive up to 10 LEDs. Again, pattern is not random, but probably "good enough". There is some variability depending on how things are connected.

Logic runs at 5v nominally, possibly down to 3v (CMOS CD4000 series) or 2v (HCMOS 74HCxxx) but lower LED drive voltage and current could be issues. Both circuits have limited LED drive current, without adding extra complexity, but work OK with small microdot LEDs which are fairly bright at 1mA or less.

I'll continue to tinker with this for a while.

Dave
 
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Dave_H

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I'll toss in another simple circuit using MC74HC14 chip which can flash up to six LEDs, possibly 12 or 18 if paralleled. Up to six inverters are set up as oscillators with one
resistor and capacitor each, all running at indepedent frequency.

Circuit runs down to 2v but operation depends on LED vf and current, better at 3v (e.g. CR2032) using red, green, yellow or orange LEDs; blue and white possible but have higher vf.

Flash on-time is not easily adjusted, however, cross-connecting LEDs in opposing pairs between outputs causes more variation. Effect is still not random, and cross-connected LEDs are not independent (one is off when the other is on). Nevertheless, it's a cheap way to go.


Dave
 
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