Can someone help me with a circuit that will light up 5 leds in parallel without usin

[Ishikawa]

I apologize for this

Deleted by original poster (sorry for the mess I had to do this, red further below for the real question)

 

[Gordz]

The problem here is that the first one will not turn on until you reach about 2 volts which is the forward voltage for a red LED. If that is going to be a problem google for LM3914 and take a look at that.

 

[Ishikawa]

I apologize for this

Deleted by original poster (sorry for the mess I had to do this, red further below for the real question)

 

[Nigel Goodwin]

Your question is really pretty vague?, do you just want to make a sweeping pattern at a fixed speed?.

Easy answer use a PIC - parts list:

1 x PIC (programmed)
5 x LED
5 x resistor
1 x 5V supply

A tiny 8 pin PIC would be enough, and the simple PICAXE version would be more than enough for the job, and is cheap, and easy to programme.

Bear in mind as one LED is always ON, you only need four channels, connect the first one simply across the supply (via a resistor of course).

 

[bananasiong]

Another thing which I forgot to mention, to light up leds in a certain sequence or pattern does each led have to be connected to a wire, can't the leds be connected together and then connect the necessary wires to the first and last led at most without touching the other leds and achive the pattern I described above?

Thanks

Can you draw that out? That will be easier for us to see.
You can only connect one side of them together, either the anode or cathode.

As Nigel said, it's easier to use a PIC.

 

[Ishikawa]

OK here r the pictures of what I'm trying to do look at them on order please from 1-7.



















I should done this from the beginning I got those picture from a video, all the leds of the heart would blink 3 times and then turn on the leds in the sequence as show in the pictures.

However how did he manage to turn on the leds in that sequence with only 5 wires connected to the circuit?

I I were to do that I would use something like a counter and connect each Q output to a row of the heart so if u count the number or rows that will light up in that sequence it would around 9 rows.

So I'm mostly curious is how did he manage to do that with only 5 wires connected to the circuit.

Note: There doesn't seem to be any resistors. transistors, gates in between the leds.

Also is that a pcb board? it looks a bit soft kinda a like sheet of paper no?

Thanks

 

[Nigel Goodwin]

So I'm mostly curious is how did he manage to do that with only 5 wires connected to the circuit.

Don't forget, he's only switching four LED's, not five, the 5th is permanently wired.

 

[mvs sarma]

He has atleast 14 LEDs positioned in a pettern as we could see the 5th photo from the top. when all of them are ON.

 

[Ishikawa]

That is how the heart is turning on, so if u look at the rows of the same color, each is a stage so if u count them excluding the first on because it is alway on u have another 8 stages turning on one after the other and when they reach the (light blue dot) they start turning off on one after the other until they reach the first one (red dot) and then they turn on again, this is done 3 times and then all the leds blink 3 times and then they turn on in they way I just described and so on.

so how can he turn on the other 8 stages with only 4 wires left?

Nigel Goodwin: Don't forget, he's only switching four LED's, not five, the 5th is permanently wired

There is a total of 16 leds (9 stages being turned on in total) the first one (red dot) is always on, so there is 15 leds left being turned on 2 at a time expect the last one (light blue dot) which is 1, so there is 8 stages left turning on.

Thanks

 

[ericgibbs]

hi,
Looking at your 1st posting LED pattern, I would agree with Gordz, a LM3914 set for bar mode. Drive the input of the LM3914 with a ramp voltage.

If your LED's require more current than the LM can supply, use the LM to drive 4/5 transistors, which drive the LED's.

 

[Nigel Goodwin]

That is how the heart is turning on, so if u look at the rows of the same color, each is a stage so if u count them excluding the first on because it is alway on u have another 8 stages turning on one after the other and when they reach the (light blue dot) they start turning off on one after the other until they reach the first one (red dot) and then they turn on again, this is done 3 times and then all the leds blink 3 times and then they turn on in they way I just described and so on.

so how can he turn on the other 8 stages with only 4 wires left?

Right, so we're not discussing your 5 LED design anymore then? - you can feed more LED's with less wires by multiplexing or charlieplexing the connections.

 

[micro_1]

From Ishikawa's description, I can imagine the operating sequence of the LEDs. Although the circuit can be designed using sequential machine technique and implemented with counters & logic gates. The design work is not easy and simplifying the logic equations is difficult. The involved logic variables may be up to 7 or 8 at least I guess. So the simpliest way I would agree with Nigel - use a PIC.

regards,

micro_1

 

[bananasiong]

Can multiplexing done for 8 stages with only 4 I/O? If common cathode or common anode is used for the LEDs, then 4 I/O is not enough. There's another way to do it.
Check this out. In page 3
https://www.electro-tech-online.com/custompdfs/2007/11/00234a.pdf

With 4 I/O pins, 12 stages can be driven

 

[Ishikawa]

Sorry about the mess

Forget about my first post. start from the heart pictures.

Thanks Nigel Goodwin ....I'll look into (multiplexing or charlieplexing the connections).

Also I'll look into **broken link removed**.

The whole point of my project is to do it just like it is shown in the pictures so let's forget about the counter and timers.

I wanna do it such that my circuit will result just like it is shown in the pictures.

So is it a sure thin that he might have used multiplexing or charlieplexing?

Also amazingly he seems to be powering it up using a mobile phone battery and a mobile phone battery has a 3.6V and at least 900mAH, so the circuit doesn't seem to consume much power despite the number of leds. That is also one of the reasons y I believe he doesn't seem to be using IC chips. Very hard to power up an IC hip on 3.6V battery

 

[Nigel Goodwin]

That is also one of the reasons y I believe he doesn't seem to be using IC chips. Very hard to power up an IC hip on 3.6V battery

Don't you think mobile phones use chips?.

There are plenty of PIC's that will work off 3.6V, and it's VERY likely that a PIC (or other micro-controller) is used to drive the LED's.

BTW, the PIC application note is an example of charlieplexing.

 

[Ishikawa]

Nigel Goddwin : Don't you think mobile phones use chips?.

Yes I do.

I'll use a pic and charlieplexing

 

[Nigel Goodwin]

Some one who does a lot of PIC charlieplexing will probably be along shortly!

 

[Ishikawa]

I just noticed that with the charlieplexing method will probably be hard to keep each row of leds ON like it is shown in the pictures.

This method will turn them ON and turn them off by the time it turns ON the next row of leds.

 

[Nigel Goodwin]

I just noticed that with the charlieplexing method will probably be hard to keep each row of leds ON like it is shown in the pictures.

This method will turn them ON and turn them off by the time it turns ON the next row of leds.

You do it so fast you can't tell they are flashing, it's a VERY standard technique.

 

[Ishikawa]

deleted by original poster.