Searching \ for '[SX] Multi LED with sx power question...' in subject line. ()
Make payments with PayPal - it's fast, free and secure! Help us get a faster server
FAQ page: www.piclist.com/techref/ubicom/lib/io/index.htm?key=led
Search entire site for: 'Multi LED with sx power question...'.

Exact match. Not showing close matches.
PICList Thread
'[SX] Multi LED with sx power question...'
2006\01\08@225208 by jgjonolan/a

flavicon
face
In SX Microcontrollers, SX/B Compiler and SX-Key Tool, jgjonola wrote:

I am looking to make a project where the sx will be controlling about 15 led's off of 1 pin. ( times 3 pins, so a total of 45 led's) I was wondering if anyone could help me...I was hoping to use a 12 volt power supply.  What is the best resistor configuration?  Parallel?  Series? Here is a link to the led's that i will be using jg@ittservice.com
IT Tech Services
---------- End of Message ----------

You can view the post on-line at:
http://forums.parallax.com/forums/default.aspx?f=7&p=1&m=104178
Need assistance? Send an email to the Forum Administrator at forumadmin@parallax.com
The Parallax Forums are powered by dotNetBB Forums, copyright 2002-2006 (http://www.dotNetBB.com)

2006\01\09@035311 by javalinn/a

flavicon
face
In SX Microcontrollers, SX/B Compiler and SX-Key Tool, javalin wrote:

Hi,
I would look at using a darlington transister IC to act as a "switch" controlled by the SX pin.  The SX is unlikely to be able to power 45 LEDS off of one pin.  The darlington will switch the power on/off dependant on how the pin is set on the SX - i.e. High or Low.

There is a Nults and Volts article on this, on the www.parallax.com website.  Its book1, article number 6
I would guess the leds in parallel would give the best brightness - not 100% but im sure somebody else will correct if this is not the case!  I think serial leds will suffer from voltage drop further down the line.

Hope this helps.

James
---------- End of Message ----------

You can view the post on-line at:
http://forums.parallax.com/forums/default.aspx?f=7&p=1&m=104178#m104188
Need assistance? Send an email to the Forum Administrator at forumadmin@parallax.com
The Parallax Forums are powered by dotNetBB Forums, copyright 2002-2006 (http://www.dotNetBB.com)

2006\01\09@040400 by beann/a

flavicon
face
In SX Microcontrollers, SX/B Compiler and SX-Key Tool, bean wrote:

John,
 The datasheet shows that the forward voltage is 3.65V typical and could be as high as 4.2V. So with a 12 Volt supply you could only run 2 of them in series (with a resistor). Unless you bump up the voltage with a multiplier or something. And yes you will need a transistor because of the higher voltage and total current required.
Or you may want to investigate something like the STP16C596, I just discovered this beauty for a project I'm working on. It would allow you to control 32 of your LEDs with nothing more than this chip, it's even got constant current so you don't even need a resistor.
Bean.

---------- End of Message ----------

You can view the post on-line at:
http://forums.parallax.com/forums/default.aspx?f=7&p=1&m=104178#m104191
Need assistance? Send an email to the Forum Administrator at forumadmin@parallax.com
The Parallax Forums are powered by dotNetBB Forums, copyright 2002-2006 (http://www.dotNetBB.com)

2006\01\09@063736 by Johnson Rodn/a

flavicon
face
In SX Microcontrollers, SX/B Compiler and SX-Key Tool, Johnson Rod wrote:

how do you get 32led's out of the 16io device?

---------- End of Message ----------

You can view the post on-line at:
http://forums.parallax.com/forums/default.aspx?f=7&p=1&m=104178#m104207
Need assistance? Send an email to the Forum Administrator at forumadmin@parallax.com
The Parallax Forums are powered by dotNetBB Forums, copyright 2002-2006 (http://www.dotNetBB.com)

2006\01\09@073854 by Chris Savagen/a

flavicon
face
In SX Microcontrollers, SX/B Compiler and SX-Key Tool, Chris Savage wrote:

Nick,
  Two in series on each I/O...Most likely through two ULN2803s or some transistors.

---------- End of Message ----------

You can view the post on-line at:
http://forums.parallax.com/forums/default.aspx?f=7&p=1&m=104178#m104218
Need assistance? Send an email to the Forum Administrator at forumadmin@parallax.com
The Parallax Forums are powered by dotNetBB Forums, copyright 2002-2006 (http://www.dotNetBB.com)

2006\01\09@075207 by beann/a

flavicon
face
In SX Microcontrollers, SX/B Compiler and SX-Key Tool, bean wrote:

Nick,
 Right two in series connected to 12V. You don't need a driver chip. The STP16C596 IS the driver chip. So you would have +12V going to 2 of the LEDs in series, then right into the STP chip. It basically acts like a shift register with constant current sink capability. It also has a single resistor to set the sink current of all outputs. It's a great chip for controlling LEDs from voltages higher than +5V.
Bean.

---------- End of Message ----------

You can view the post on-line at:
http://forums.parallax.com/forums/default.aspx?f=7&p=1&m=104178#m104224
Need assistance? Send an email to the Forum Administrator at forumadmin@parallax.com
The Parallax Forums are powered by dotNetBB Forums, copyright 2002-2006 (http://www.dotNetBB.com)

2006\01\09@080529 by Chris Savagen/a

flavicon
face
In SX Microcontrollers, SX/B Compiler and SX-Key Tool, Chris Savage wrote:

Interesting chip Bean, never heard of it before.

---------- End of Message ----------

You can view the post on-line at:
http://forums.parallax.com/forums/default.aspx?f=7&p=1&m=104178#m104229
Need assistance? Send an email to the Forum Administrator at forumadmin@parallax.com
The Parallax Forums are powered by dotNetBB Forums, copyright 2002-2006 (http://www.dotNetBB.com)

2006\01\09@122919 by beann/a

flavicon
face
In SX Microcontrollers, SX/B Compiler and SX-Key Tool, bean wrote:

Chris,
 Another cool LED chip is the M5451 is is a constant current sink IC that controls 35 LEDs. Shift register in parallal outputs. Limited to 15mA sink per output, but nice when you have a bunch of LEDs to control since you don't need a bunch of resistors.
Bean.

---------- End of Message ----------

You can view the post on-line at:
http://forums.parallax.com/forums/default.aspx?f=7&p=1&m=104178#m104262
Need assistance? Send an email to the Forum Administrator at forumadmin@parallax.com
The Parallax Forums are powered by dotNetBB Forums, copyright 2002-2006 (http://www.dotNetBB.com)

2006\01\09@140744 by Electronegativityn/a

flavicon
face
In SX Microcontrollers, SX/B Compiler and SX-Key Tool, Electronegativity wrote:

Here's a nice application note I found on using the STP16C596, it shows the details of how to clock in data.

---------- End of Message ----------

You can view the post on-line at:
http://forums.parallax.com/forums/default.aspx?f=7&p=1&m=104178#m104273
Need assistance? Send an email to the Forum Administrator at forumadmin@parallax.com
The Parallax Forums are powered by dotNetBB Forums, copyright 2002-2006 (http://www.dotNetBB.com)

2006\01\10@131337 by drnown/a

flavicon
face
In SX Microcontrollers, SX/B Compiler and SX-Key Tool, drnow wrote:

Bean:

Interesting LED project you describe.  As for other LED driver chips, I found a couple from TI for a project I'm working on.  If you need brightness adjustability on 16 LED lines, check out TLC 5940 and/or TLC 5923.  I like the 5923 because it's a little simpler, and still provides 127 brightness levels.

Jim C
---------- End of Message ----------

You can view the post on-line at:
http://forums.parallax.com/forums/default.aspx?f=7&p=1&m=104178#m104385
Need assistance? Send an email to the Forum Administrator at forumadmin@parallax.com
The Parallax Forums are powered by dotNetBB Forums, copyright 2002-2006 (http://www.dotNetBB.com)

2006\01\10@133432 by Coriolisn/a

flavicon
face
In SX Microcontrollers, SX/B Compiler and SX-Key Tool, Coriolis wrote:

Theres also the MAX7313, while it doesn't have all the capabilities of the TI devices (for instance it has a max LED voltage of 5V so it cannot be used in this application, and only has 16 levels of individual LED brightness), but it does have the ability to set each channel (16) as input, output, or PWM, and is $.65 cheaper than the TLC5923.

---------- End of Message ----------

You can view the post on-line at:
http://forums.parallax.com/forums/default.aspx?f=7&p=1&m=104178#m104390
Need assistance? Send an email to the Forum Administrator at forumadmin@parallax.com
The Parallax Forums are powered by dotNetBB Forums, copyright 2002-2006 (http://www.dotNetBB.com)

2006\01\11@004526 by jgjonolan/a

flavicon
face
In SX Microcontrollers, SX/B Compiler and SX-Key Tool, jgjonola wrote:

thanks for all the responses.  I will look into a them and let you know how they worked out!

John G
---------- End of Message ----------

You can view the post on-line at:
http://forums.parallax.com/forums/default.aspx?f=7&p=1&m=104178#m104453
Need assistance? Send an email to the Forum Administrator at forumadmin@parallax.com
The Parallax Forums are powered by dotNetBB Forums, copyright 2002-2006 (http://www.dotNetBB.com)

2006\01\12@182811 by beann/a

flavicon
face
In SX Microcontrollers, SX/B Compiler and SX-Key Tool, bean wrote:

If anyone cares, here is a picture of the 4" high 4-digit 7-segment green display.
I used a BS2 and STP16C596 and 4 PNP transistor with a 1K base resistor.

You don't need any current limit resistors, just one resistor to set the current for all segments (that means equal brightness).


Bean.

---------- End of Message ----------

You can view the post on-line at:
http://forums.parallax.com/forums/default.aspx?f=7&p=1&m=104178#m104731
Need assistance? Send an email to the Forum Administrator at forumadmin@parallax.com
The Parallax Forums are powered by dotNetBB Forums, copyright 2002-2006 (http://www.dotNetBB.com)

2006\01\13@004917 by jgjonolan/a

flavicon
face
In SX Microcontrollers, SX/B Compiler and SX-Key Tool, jgjonola wrote:

Ok, I was looking at those chips, but they are a bit more complicated than I need.  I am sorry, I should have been more clear in my original post.  I am looking to put a board together that has an sx at its heart.  It has an input pin that tells it to turn on, when activated, it starts a string of led's "crawling"  so the first pin would be connected to 15 led's, second pin to 15 led's, and 3rd pin to 15 led's.  

like this:

123123123123123123123123123123123
As you can see, turning on pin 1, then 2, then 3 would make it look as if the led's are crawling.  The 12v power source is not nessesary, I could just as easily use 5v. I'm just going to use a wall wart.  There will be 13 of these boards connected to the same power supply, and there is a posibility that they would all be on steady at the same time.

Thanks again,
John G
PS- Since i am in a hurry, I would be willing to pay for someone to design the schematics for me.  (I really do want to tackle this myself, but time is running out)  Contact me if you are interested!

---------- End of Message ----------

You can view the post on-line at:
http://forums.parallax.com/forums/default.aspx?f=7&p=1&m=104178#m104757
Need assistance? Send an email to the Forum Administrator at forumadmin@parallax.com
The Parallax Forums are powered by dotNetBB Forums, copyright 2002-2006 (http://www.dotNetBB.com)

2006\01\13@052820 by beann/a

flavicon
face
In SX Microcontrollers, SX/B Compiler and SX-Key Tool, bean wrote:

John,
 I WOULD use the 12V supply. You will be able to put more LEDs in series with the higher voltage. With 5V you could only put 2 LEDs in series, with 12V you could put 5 LEDs in series.

 Basically you would have 3 strings of 5 LEDs and 1 resistor (220 ohms ?). Connect the one end of each string to +12V, connect the other end to a NPN (2N2222) transistor collector. Connect the transistor emitter to ground. Connect the transistor base to a 1K resistor, and the other end of the 1K resistor to an SX output pin. When the pin goes high the LEDs should light.

 Connect the other 2 strings to +12V and to the SAME transistor collector.

That takes care of 1 set of 15 LEDs.

Now just repeat for the other 2 sets of 15 LEDs, using another transistor and another SX output pin.

45 LEDs, 9 (220 ohm) resistors, 3 NPN (2N2222) transistors, 3 1K resistors.

Sorry I don't have time to make a schematic right now.
I hope this helps...
Bean.

---------- End of Message ----------

You can view the post on-line at:
http://forums.parallax.com/forums/default.aspx?f=7&p=1&m=104178#m104767
Need assistance? Send an email to the Forum Administrator at forumadmin@parallax.com
The Parallax Forums are powered by dotNetBB Forums, copyright 2002-2006 (http://www.dotNetBB.com)

2006\01\13@080937 by Electronegativityn/a

flavicon
face
In SX Microcontrollers, SX/B Compiler and SX-Key Tool, Electronegativity wrote:

Hi Bean, is there any reason why Jgjonola couldn't work at 5V and put all the LED's on each string in parallel?

They could be controlled in a simple manner from the SX by a Darlington array like this one, or equivalent:

http://www.mouser.com/index.cfm?handler=displayproduct&lstdispproductid=748020&e_categoryid=279&e_pcodeid=51113

ST makes a 5V regulator that puts out 5 amps and you can get it here for about $1.50:

http://www.mouser.com/index.cfm?&handler=data.listcategory&D=*511LD1084D2M50TR*&terms=511-LD1084D2M50-TR&Ntt=*511LD1084D2M50TR*&Dk=1&Ns=SField&N=0&crc=true
At 20mA/LED that's 250 LED's, and he could power the everything off the same supply.

---------- End of Message ----------

You can view the post on-line at:
http://forums.parallax.com/forums/default.aspx?f=7&p=1&m=104178#m104788
Need assistance? Send an email to the Forum Administrator at forumadmin@parallax.com
The Parallax Forums are powered by dotNetBB Forums, copyright 2002-2006 (http://www.dotNetBB.com)

2006\01\13@083414 by beann/a

flavicon
face
In SX Microcontrollers, SX/B Compiler and SX-Key Tool, bean wrote:

Sure he could,
 But you would have to connect alot more resistors and it would be alot less power effecient.
 With a single LED and resistor you need 20mA per LED. With a string of 5 you need 20mA per 5 LEDs.
 So 5V @ 5 amps = 25Watts or 12V @ 1 Amp = 12Watts.
 Plus you would need heaver wire to carry the current.

 Depending on the physical construction it may make more sense to wire each LED individually though.

Bean.

---------- End of Message ----------

You can view the post on-line at:
http://forums.parallax.com/forums/default.aspx?f=7&p=1&m=104178#m104794
Need assistance? Send an email to the Forum Administrator at forumadmin@parallax.com
The Parallax Forums are powered by dotNetBB Forums, copyright 2002-2006 (http://www.dotNetBB.com)

2006\01\13@090038 by Electronegativityn/a

flavicon
face
In SX Microcontrollers, SX/B Compiler and SX-Key Tool, Electronegativity wrote:

I am thinking of a situation with 15 20mA LEDs in parallel per string, and each string hooked up to one pin of the STP16C596.

Since the driver can easily be set to output 300mA constant current per pin, you would only need a single resistor for all the LEDs.

If power efficiency is an issue, the driver's supply voltage could be stepped down to slightly above Vf.

---------- End of Message ----------

You can view the post on-line at:
http://forums.parallax.com/forums/default.aspx?f=7&p=1&m=104178#m104797
Need assistance? Send an email to the Forum Administrator at forumadmin@parallax.com
The Parallax Forums are powered by dotNetBB Forums, copyright 2002-2006 (http://www.dotNetBB.com)

2006\01\13@094419 by beann/a

flavicon
face
In SX Microcontrollers, SX/B Compiler and SX-Key Tool, bean wrote:

It's bad to connect LED in parallal without a resistor because each one will have a slightly different Vf voltage so you will get some bright LEDs and some dim LEDs.

Besides the STP16C596 can only supply 120mA per output.

Bean.

---------- End of Message ----------

You can view the post on-line at:
http://forums.parallax.com/forums/default.aspx?f=7&p=1&m=104178#m104813
Need assistance? Send an email to the Forum Administrator at forumadmin@parallax.com
The Parallax Forums are powered by dotNetBB Forums, copyright 2002-2006 (http://www.dotNetBB.com)

2006\01\13@095953 by Electronegativityn/a
flavicon
face
In SX Microcontrollers, SX/B Compiler and SX-Key Tool, Electronegativity wrote:

Hi Bean.

Oops, you're right about the 120mA per pin, that would have been bad.

If each LED has a slightly different Vf, then won't there be some bright and some dim regardless of whether they are in serial or parallel?

---------- End of Message ----------

You can view the post on-line at:
http://forums.parallax.com/forums/default.aspx?f=7&p=1&m=104178#m104815
Need assistance? Send an email to the Forum Administrator at forumadmin@parallax.com
The Parallax Forums are powered by dotNetBB Forums, copyright 2002-2006 (http://www.dotNetBB.com)

2006\01\13@101941 by beann/a

flavicon
face
In SX Microcontrollers, SX/B Compiler and SX-Key Tool, bean wrote:

No, LED brightness is controlled by the amount of current that flows through them. In a series circuit all elements have the same amount of current flowing through them regardless of the voltage drop.

Bean.

---------- End of Message ----------

You can view the post on-line at:
http://forums.parallax.com/forums/default.aspx?f=7&p=1&m=104178#m104818
Need assistance? Send an email to the Forum Administrator at forumadmin@parallax.com
The Parallax Forums are powered by dotNetBB Forums, copyright 2002-2006 (http://www.dotNetBB.com)

2006\01\13@102437 by Electronegativityn/a

flavicon
face
In SX Microcontrollers, SX/B Compiler and SX-Key Tool, Electronegativity wrote:

Thanks Bean, that's good to know.

---------- End of Message ----------

You can view the post on-line at:
http://forums.parallax.com/forums/default.aspx?f=7&p=1&m=104178#m104819
Need assistance? Send an email to the Forum Administrator at forumadmin@parallax.com
The Parallax Forums are powered by dotNetBB Forums, copyright 2002-2006 (http://www.dotNetBB.com)

2006\01\13@102504 by beann/a

flavicon
face
In SX Microcontrollers, SX/B Compiler and SX-Key Tool, bean wrote:

Another thing you can do is connect 5 LEDs in series to +12V then through a 220 ohm resistor to a SX pin. The voltage drop through the diodes should be about 8.5 volts. That presents the SX pin with about 3.5V through the resistor. When the SX pin is high (+5) no current will flow, when the SX pin is low the LEDs will light and will only pull about 20mA from the SX pin.

You don't need a transistor or anything. One SX pin controlling 5 LEDs.

Bean.

---------- End of Message ----------

You can view the post on-line at:
http://forums.parallax.com/forums/default.aspx?f=7&p=1&m=104178#m104820
Need assistance? Send an email to the Forum Administrator at forumadmin@parallax.com
The Parallax Forums are powered by dotNetBB Forums, copyright 2002-2006 (http://www.dotNetBB.com)

2006\01\13@212611 by jgjonolan/a

flavicon
face
In SX Microcontrollers, SX/B Compiler and SX-Key Tool, jgjonola wrote:

thanks everyone, i think that the last solution might be the best one.  I would have to use more pins, but most of the other were going to be unused anyways...

---------- End of Message ----------

You can view the post on-line at:
http://forums.parallax.com/forums/default.aspx?f=7&p=1&m=104178#m104886
Need assistance? Send an email to the Forum Administrator at forumadmin@parallax.com
The Parallax Forums are powered by dotNetBB Forums, copyright 2002-2006 (http://www.dotNetBB.com)

2006\01\14@120552 by c-isaacn/a

flavicon
face
In SX Microcontrollers, SX/B Compiler and SX-Key Tool, c-isaac wrote:

Use a regulated supply so you know you're getting 12 volts.

---------- End of Message ----------

You can view the post on-line at:
http://forums.parallax.com/forums/default.aspx?f=7&p=1&m=104178#m104943
Need assistance? Send an email to the Forum Administrator at forumadmin@parallax.com
The Parallax Forums are powered by dotNetBB Forums, copyright 2002-2006 (http://www.dotNetBB.com)

More... (looser matching)
- Last day of these posts
- In 2006 , 2007 only
- Today
- New search...