Help me with connecting 20,000 LEDs in parallel using PIC16G877A

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mousepad

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Hi All!
I want to On and Off Parallely connected 20,000 LEDs
I'm expecting to use a pic16f877a for this

My problem is

1. I don't like to use a relay for this (On/Off) 2N3055 will Ok for this ?
2. How much volt and Current should I Supply
what are the calculation for that
what are the Necessary components and Schematic

Please help me.
Thanks.
 

Re: LED 20000 on and off

20,000 LEDs connected in parallel means current is adding up... One LEDs takes about 10mA current... so 20,000 will take 20000*0.01=200Amperes :|... U`ll need a serious Magnetic Contactor (Large size relay) for that....Then u`ll need a ckt to drive Mag Contactor using power transistor cktry... what u planning to make?
 

    M

    mousepad

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Re: LED 20000 on and off

I am trying to build a LED Name board for my Shop

and i dont like to use a relay what about 2N3055 Power Transistors
 

Re: LED 20000 on and off

Definitely u can use power transistor 2N3055...I recommend u to use IRFZ44 power mosfet...Parallel the transistor for more current if required.
 

    M

    mousepad

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Re: LED 20000 on and off

HI
can Iuse computer power supply unit for this (5V):|
 

LED 20000 on and off

Are you really going to hand wire 20,000 LEDs and 20,000 current limiting resistors? What is the 16F877 supposed to do?
 

Re: LED 20000 on and off

Hi blueroomelectronics

(Are you really going to hand wire 20,000 LEDs and 20,000 current limiting resistors?) YES

I gaveup 16f877. now I am trying to just Toggle (on/Off) These LEDs I think I can use NE555 for this and expecting use to 150 ohm for each LED with 5V PC Power supply as I said earlier

is This Power supply enogh for 20,0000 LED or should i connect many of them separately

is there ary calculation to know the exact Volt , current

Thanks
 

LED 20000 on and off

If you use 5v and allowing for a 2v drop across the led, you are talking about 20ma per led. So 20x20000 = 400 Amps @ 5V. Not really practicable unless use use about 40 computer power supplies and split the load up, you would need a very good mains supply for them, and expensive to run. Normally you would run this amount of leds with fast high current short pulses, say around 50x per second. This would bring the average current down to managable levels, but would need careful calculation and suitable power supplies. As mousepad says, a great deal of work. Also there is a good chance you would not be able to read it in direct sunlight, even with high brightness leds.
 

    M

    mousepad

    Points: 2
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Re: LED 20000 on and off

a make some similar project with 2-3 000 leds
you can wire the leds :

+--res--O--O--O--
--+--res--O--O--O--
+--res--O--O--O--

I use MCU.... bufer to multiple outputs ....NPN transistors darlington......
If the current is very big put more powersupllys

+ to leds and connect GND togehter
if you wanna more info i will make a sketch

sorry for my bad english

regards from Bulgaria
 

LED 20000 on and off

20000 x 0.02 (I) x 1.2 (v) = 480 watt
yes you can use the a 480 watt power supply
but you have to connect them in series and parallel
like this
_ _
_ - - _
_ _
 

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