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pasicr

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Hi for all, I need advice from college with experiences in led driving, I have 50 led in series and I need driver with pic micro for example, also I need to light only 3 or 4 leds in same time and this will be shifted, to get moving athom effect in elipse...
regards
 

I send three logic 1 and nothing else, only clock and shift with shift register...
regards
 

Can you post the circuit so that we can help you

Nandhu
 

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    pasicr

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Instead of using PIC micro for such simple design, Just go ahead with a 10 channel chaser design with 555 and CD4017 and connect 5 led's per channel. You can also decrease the channel outputs by connecting the reset pin 15 to respective outputs where you want the count to reset. Have a look at the 10 channel LED chaser in the given link below. Cheers
**broken link removed**
 

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    pasicr

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pasicr said:
Hi for all, I need advice from college with experiences in led driving, I have 50 led in series and I need driver with pic micro for example, also I need to light only 3 or 4 leds in same time and this will be shifted, to get moving athom effect in elipse...
regards
Click to expand...
i hope its help u.
injoy with it
 

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    pasicr

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pasicr said:
I have 50 led in series [...] I need to light only 3 or 4 leds in same time and this will be shifted [...]
Click to expand...
Which of the following scenarion do you want to acheive ?
- light 1,2,3,4 then 2,3,4,5 then 3,4,5,6 etc
- light 1,2,3,4 then 5,6,7,8 then 9,10,11,12 etc

Another question - how much current do you need to drive?
 

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    pasicr

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scenario light 1,2,3,4 then 2,3,4,5 then 3,4,5,6 etc
I use red 5mm led...
regards
 

pasicr said:
scenario light 1,2,3,4 then 2,3,4,5 then 3,4,5,6 etc
I use red 5mm led...
Click to expand...
In this scenario, essentially, you need individual drive for each LED. I would recommend common anode* for all 50 LEDs instead of connecting them in series. Cathodes connected to a shift registers. I don't have the part number for the shift register on the top of my head. But I'm sure folks here can suggest specific parts.

- Nick

* Common cathode could work as well. I'll stick with common anode for certainty.
 

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    pasicr

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Hi pasicr,

You could use 'Charlieplexing'. But the output intensity may not be appreciable. Also you need multiplexing and with 8 uC pins you can control almost 56 LEDs(individually).
 

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    pasicr

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Use any microcontroller and led drive with a transistor through port pins.A simple program to drive LED
 

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    pasicr

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use a 4017 (10 bit ring counter) to source/sink the current and the PIC to sink/source teh current in an array (just as u connect the keypad matrix)
 

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    pasicr

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put the vales want to move in a matrix and write a routine to cal them accordingly..
 

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    pasicr

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matbob said:
Hi pasicr,

You could use 'Charlieplexing'. But the output intensity may not be appreciable. Also you need multiplexing and with 8 uC pins you can control almost 56 LEDs(individually).
Click to expand...

Hi
I have the same problem, I want to operate 10 LEDs in series at a time, and want with ful glow. I tried it but intensity is not goood and when I put it off by a UC the do not switch off completely mean the slightly glow.

plz help
 

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    pasicr

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There are so many display controller that will help you. I used Max7219 to drive 640 leds in an array..
 

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    pasicr

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Hi Pasicr, As Nick has suggested above, use shift registers 74HCT595 with Output enables grounded and seven(7X8=56LEDs) of them in a cascaded(Serial out of one to serial in of another) fashion.Connect them either to SPI port or simple I/O pins and use bit banging to shift data needed.If you connect the anodes of LEDs to +5V, then a 0 in the shifted data will turn the LED on. While the current is internally limited, it would be good to use a limiting resistor of 220Ohms or so.Three succesive zeroes and remaining 1s will display your 3 led on pattern.Shifting the pattern and latching will give moving pattern effect. Here as there is storage, you can clock the new data without disturbing the old pattern till it is latched.Multiplexing and Charlieplexing will help save circuitry, but if you are not an advanced hobbyist, it gets complicated. Try simple and sure ones and your ellipse will become attractive.
 

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    pasicr

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