Ok, so, am I right in thinking that if multiplexing, you can't use a ULN2003 because you need to switch the leds at the anode end to be able to address each led in the matrix?



If I'm not multiplexing, (which I don't really need to given the smallish number of leds I'm using) and use a TLC5947 to drive the leds with pwm, does it make no difference whether I use a ULN2003 type or UDN2981A type?

If so which is best (simplest ideally and have you any links to info that will help get my head around the circuitry needed between the two (and the arduino)

Feel free to tell me to 'go search Google'!  There's just a lot of information out there..

Cheers

I don't really understand this - "The ULN2003 will only sink current it will not source it."

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How are the UDN2981A and TLC59213A different from the ULN2003?

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And given that I don't need a very large number of leds, and I dont need them arranged in a square array, would I be better off with something like the TLC5940? 

And if so will this work with the UDN2981A or TLC59213A?


Thanks for being patient with my basic questions!
Will

Ah, one quick question, is it possible to use something the ULN2003A on these pwm'd channels to drive high current leds?

Thanks

Great thank you.

I will try to get my head round this.


Have you made anything similar? 

And does this allow pwm for each led individually?

cheers

If anyone wants a custom version (within reason) let me know

I knocked up a simple A4 size printable template to plan out stripboard design and attached it to this post.

Someone might find it useful

Thanks for the link

I was looking at those Maxim drivers but didn't think any of them supported PWM.  Am I wrong?

Nice to know about the free samples!

Thanks.

Possibly bit heavy for me currently but I'll try to digest it.


What's the hardware used?

Yes that worked.

Thanks!

The voltage is 5.9v  Will this be too much for the arduino pin?

Thanks, I'll have a play and get back to you

Are there any options for multiplexing leds and being able to control the brightness of each led, like pwm?

I need to control about 20 leds brightness individually from one arduino


thanks

Hi. Here's a noob question for you


I have one circuit with a power source (batteries) powering an led, controlled by a switch.

I want this same switch (single pole) to also set an arduino pin HIGH when it is pressed.


Can I use a transistor? From what I've been reading here - http://www.ermicro.com/blog/?p=423 I should be able to use something like a 2n3904 transistor to switch the arduino pin high when there is a current in the other circuit, but I cant work it out.

Am I going about this the right way?  And do both circuits need to be powered from the same power source for this to work?


Thanks

Hi all.

I need to find a way to make a number (say 16) of LEDs flash concurrently at a set rate, with the option of flash, constant on, or off.

I know this should be easy, but I need to check a few things before I start playing.

I need to embed the whole circuit in a small item of clothing so am planning to use the arduino nano. Could someone tell me how the LEDs will need to be wired to this? Do they need to be in series or parallel? Will each LED need an accompanying resistor? And what kind of battery life couuld I expect from for example, 2x 3v 260mAh button cells?

Thanks in advance for any answers/ideas!

Will