LED sequencing circuit

[daffy]

Hi...new here and have some electronics exp but not enough.

I want to build an LED sequencing project where a group of 3-5 3V 20mA high bright white LEDs are to turn on then the next group of 3-5 LEDs and so on for about 10 meters. All LED's will be about 2cm apart. The preceding LED's preferably should turn off when the next lights up. The LED's should be on for about half a second before turning off and lighting the next group. And it should start the sequence again when complete.

Is there a way that this can be done simply? I saw that there are circuits posted here with a loop of only a small amount ( less than 10) of LED's where only 555 timers are used. This is no good for my application.

 

[MikeMl]

A 555 driving a 4017 decoded decade counter would give 10 progressive outputs, or 5 with gaps between...You might want to add a hex buffer for higher current sink...

 

[vne147]

Like Mike said, you can use a circuit like **broken link removed**. If you want to turn on a group of 3 - 5 LEDs at a time you won't be able to directly drive them off the 4017 like it's shown in the diagram. Instead, you can have each ouput of the 4017 turn on an NPN transistor that will drive the LEDs.

 

[Boncuk]

Hi daffy,

how many groups of LEDs are you planning to use over a distance of 10m?

If a group of LEDs is used with the LEDs arranged in horizontal order a group of 5 LEDs will require a total of 2,500 LEDs, if arranged vertically the total number of LEDs will be 25,000.

A single counter with 5 usable outputs won't suffice for your application. So you require multiple counters cascaded for the proper sequence.

Also, do all groups have to be lit in sequence, or do you want to light group 1 and 6, then 2 and 7 and so on?

Boncuk

 

[Boncuk]

Like Mike said, you can use a circuit like **broken link removed**

Invalid URL

 

[Dragon Tamer]

the URL worked for me. if he is trying to run 10 meters worth of LED's, each spaced 2cm apart that's over 5000 LED's, that is either a lot of 4017 ic's (if he's trying to get them to all be sequential) or he may need to drive a considerable transistor if he only wants to sequence 10 (which is still 500 LED's on at a time). he can try an LED sequencing circuit combined with multiple driving output. like this circuit (thanks to audioguru for finding it): 4017 sequence

 

[BrownOut]

I think he meant to write "10 minutes" I could be wrong, as I can't make much sense of the question.

 

[mbarazeen]

the URL worked for me. if he is trying to run 10 meters worth of LED's, each spaced 2cm apart that's over 5000 LED's, that is either a lot of 4017 ic's (if he's trying to get them to all be sequential) or he may need to drive a considerable transistor if he only wants to sequence 10 (which is still 500 LED's on at a time). he can try an LED sequencing circuit combined with multiple driving output. like this circuit (thanks to audioguru for finding it): 4017 sequence

i think its 500 LEDs, and if its grouped then 5 LEDsx100 groups.

so use a 4017 as primary counter X axis, and another 4017 to count its resets Y axis . so totally a matrix of 10x10 = 100.
by taking out from 1st counter and another out from 2nd counter and making them by and AND out driver transistor (ie when both are high the transistor will drive the group of 5) this task can be completed.

i think he may need
555 - 1
4017-2
ressitors and transistors - 100 x2 each (its like switch on two transsitors to get one group on.

Edit: one transistor can be used as a emitter follower and other as a switch, use current limiting resistor and the group of LEDs to connect both transistors emitter and collector respectively.

 

[Boncuk]

I think he meant to write "10 minutes" I could be wrong, as I can't make much sense of the question.

10 minutes don't make much sense either.

That's what duffy posted:

I want to build an LED sequencing project where a group of 3-5 3V 20mA high bright white LEDs are to turn on then the next group of 3-5 LEDs and so on for about 10 meters.

I guess he meant to build some kind of a LED chaser of 10m length with the LEDs spaced 2cm. One group contains between three and five LEDs, which totals 15,000 respectively 25,000 LEDs if they are arranged in columns.

The total number of LEDs required reduces to 5,000 if one group of five is arranged horizontally, no matter how many LEDs belong to a group.

Since only three or five LEDs will be lit at a time the power consumption will be relatively low, but the counter ICs and wires will be quite a lot - even using charlieplexing or matrix coding.

I've never tried to cascade 625 decade counters (with eight usable outputs) over a lenght of 10,000cm. I guess the clock signal needs to be buffered every 100cm.

If one group is arranged horizontally and contains 5 LEDs it still means 125 counter ICs.

Boncuk

 

[mbarazeen]

if i am not mistaken he mentioned 10m = 10x100cm = 1000 cm.
spacing is = 2cm
no of LED used = 1000/2 = 500

Edit: if 5 LEDs in the group then total of 100 groups only.

 

[BrownOut]

If there are 5 per "group", that's 5X500= 2500, not 25,000! Whatever, seems like everyone gets something different from the post

 

[Dragon Tamer]

problem is he's too vauge in his origonal post.

 

[Boncuk]

if i am not mistaken he mentioned 10m = 10x100cm = 1000 cm.
spacing is = 2cm
no of LED used = 1000/2 = 500

You are right!

Sorry, math error on my side.

Stlll a lot of LEDs.

 

[vne147]

I thought of this last night. Is there any reason this idea wouldn't work? It uses 1 555, 3 4017s, 65 NPNs, and 10 current limiting resistors to sequence 500 LEDs each staying on for ~ .5 seconds. I think given a high enough supply voltage, the idea could be expanded indefinitely. For 2 4017s 100 LEDs, 3 4017s 1000, 4 4017s 10000, etc. What does everyone think?

 

[BrownOut]

Eventually, you would reach a limit on the fanout for the 4017, and would need a different scheme.

 

[vne147]

Eventually, you would reach a limit on the fanout for the 4017, and would need a different scheme.

What limit would you reach?

Edit: Are you talking about leakage current through the 10KΩ resistors and the bottom transistors eventually adding up to the source capabiltiy of the 4017's output pins?

 

[BrownOut]

Every transistor that drives the LED's require a small bias current. No device will drive an indefinite number of transistors. What is the purpose of this system anyway?

 

[vne147]

Every transistor that drives the LED's require a small bias current. No device will drive an indefinite number of transistors.

Understand, thanks.

What is the purpose of this system anyway?

I have no idea. Maybe the OP can answer.

 

[Ubergeek63]

Hi...new here and have some electronics exp but not enough.

I want to build an LED sequencing project where a group of 3-5 3V 20mA high bright white LEDs are to turn on then the next group of 3-5 LEDs and so on for about 10 meters. All LED's will be about 2cm apart. The preceding LED's preferably should turn off when the next lights up. The LED's should be on for about half a second before turning off and lighting the next group. And it should start the sequence again when complete.

Is there a way that this can be done simply? I saw that there are circuits posted here with a loop of only a small amount ( less than 10) of LED's where only 555 timers are used. This is no good for my application.

there is a simple way if they are simple chasers... sequencing is simple if you use one to trigger the next and so on down the line.

 

[dougy83]

there is a simple way if they are simple chasers... sequencing is simple if you use one to trigger the next and so on down the line.

If you want 1 driver per group of LEDs. It's going to work out to be very expensive and not simple to wire up. I must say I prefer vne147's matrixed version which uses minimal parts.