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### Topic: Need Help with Bipolar LED's and minimal digital pins (Read 5227 times)previous topic - next topic

#### Kenn13542

##### Jun 22, 2013, 02:34 am
Hi,
In the photo below I have drawn a ruff diagram of my idea to use bi polar LED's. I will be using 8 LED's and don't have 16 pins for both the blue and yellow pins from the LED (Blue and Yellow are the bipolar colours from the LED). What i am trying to accomplish is I can control all 8 LED's separately and choose to switch all of them from blue to yellow if I wish with only using a total of 10 pins (8 for the LED's and 2 for the switching between either blue or yellow).

The voltage in is 9.6v and then splits to the 8 LED's (In this diagram I didn't show all 8 because they all have the same circuitry). Then Pins 3-10 will control the LED's, ON/OFF state. After that the Pins 1 and 2 are attached to all the LED's (Pin 1= Blue    Pin 2= Yellow).

So what I am asking is will this work or will it not and maybe even some suggestions as well are appreciated.
NOTE: The schematic doesn't show the two legs for the Blue and Yellow on the LED, so just imagine they are their.

Thanks, Ken

#### runaway_pancake

#1
##### Jun 22, 2013, 03:20 am
Why don't you take some time and document that which you propose instead of asking that the rest be imagined, or implied, or assumed?
"Who is like unto the beast? who is able to make war with him?"
When all else fails, check your wiring!

#### Kenn13542

#2
##### Jun 22, 2013, 06:45 am
Help would be better than criticism. I am new to this and would like some assistance that's all.

#### runaway_pancake

#3
##### Jun 22, 2013, 03:10 pm
I have not critcised you.
You stated that your proposal is incomplete but you complain that I ask for clarification?

I suggested that you document what the devil you're on about as stuff like

... I have drawn a ruff diagram... So what I am asking is will this work or will it not and maybe even some suggestions as well are appreciated.
NOTE: The schematic doesn't show the two legs for the Blue and Yellow on the LED, so just imagine they are their.

isn't "helpful", or conducive to your desire, presumably, to garner "help" at all.
"Who is like unto the beast? who is able to make war with him?"
When all else fails, check your wiring!

#### nickgammon

#4
##### Jun 23, 2013, 12:14 am
You could use two shift registers to control 16 pins.

http://www.gammon.com.au/forum/?id=11518

That could be a lot simpler than a whole heap of transistors.

As for your proposal, I'm not sure. Try making up one leg of it (one resistor, 3 transistors and one LED) and see for yourself. But I think you are going to end up with a whole lot more parts than two shift registers and one resistor per LED (leg).
Please post technical questions on the forum, not by personal message. Thanks!

#### Kenn13542

#5
##### Jun 23, 2013, 02:18 am
Ok thanks, I'll look into shift registers and see what I can find.
Thanks, Ken

#### Grumpy_Mike

#6
##### Jun 23, 2013, 04:54 am
Quote
In the photo below I have drawn a ruff diagram of my idea to use bi polar LED's.

The rough diagram does not show bi polar LEDs at all.

These are LEDs that show one colour when connected one way round in a circuit and the other colour the other way round. Therefore to drive them with a single rail system you need a circuit called a H-bridge, these are normally used for controlling motors.

So what do you actually mean?
Do you have a bi polar LED or do you have a two colour LED, if so is the package common anode / cathode / access to both?

#### Kenn13542

#7
##### Jun 23, 2013, 12:15 pm
I did mention that the schematic diagram I did was done in a program that only had a one Colour LED.
Quote
NOTE: The schematic doesn't show the two legs for the Blue and Yellow on the LED, so just imagine they are their.

But the LED is a bi polar LED with 3 legs for blue, yellow and ground.

#### Grumpy_Mike

#8
##### Jun 23, 2013, 12:21 pm
Quote
But the LED is a bi polar LED with 3 legs for blue, yellow and ground.

If it has three legs it is not a bipolar LED.

Quote
the schematic diagram I did was done in a program that only had a one Colour LED.

So what you should do is to use two symbols and put a note on the diagram.

Quote
NOTE: The schematic doesn't show the two legs for the Blue and Yellow on the LED, so just imagine they are their.

My imagination has a hard time deciding if they are common anode or common cathode LEDs and if so where the missing wires actually go.

As drawn the diagram is a nonsense, so I will use my imagination and say yes it is perfectly fine.

Please note the quality of an answer is only as good as the quality of a question.

#### Kenn13542

#9
##### Jun 23, 2013, 12:37 pm
Thankyou for the tip on putting 2 leds instead of one on the schematic because the program doesn't have it and also someone finally answering the question.

#### Kenn13542

#10
##### Jun 23, 2013, 12:55 pm
This is the LED I am using:
http://www.ebay.com/itm/5pcs-5mm-Bi-Polar-Common-Cathode-Amber-Blue-Led-YB5L-/390363709584?pt=LH_DefaultDomain_0&hash=item5ae37d8090

It does have 3 legs and says its bi polar, so is that not the proper term?

#### fungus

#11
##### Jun 23, 2013, 01:40 pm

It does have 3 legs and says its bi polar, so is that not the proper term?

I'm guessing he meant bi-color.

The rest of the text looks machine-translated so the meaning might have been lost.
No, I don't answer questions sent in private messages (but I do accept thank-you notes...)

#### Kenn13542

#12
##### Jun 23, 2013, 01:44 pm
Ok cool, thanks for everyone's help.

#### Grumpy_Mike

#13
##### Jun 23, 2013, 01:58 pm
Quote
the polar has to be automatically reserve by the circuit in order to make it flashing.

That phrase from the web site is pure nonsense. If reserved means reversed then it makes more sense only it does not apply to what they are selling.

Polar is short for polarity and there are some LEDs that show one colour when powerd in one direction and another colour when powered in the other. This is not the case here.

If you want to do another diagram showing the common cathode and where all the base signals come from we will be happy to comment on it.

#### Kenn13542

#14
##### Jun 23, 2013, 11:51 pm
Thanks for that tip, I'll see how it goes when my ED's arrive.
Thanks, Ken

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