Hello,
I am beginner in electronics and I would like to learn about arduino. Actually, I am working on my first project → Build a score board with red led strips.
I bought :
I am wondering, if I could connect my 12v alim (by jack connector) to my arduino safely and do shine my leds ?
Thanks !
You need to power the LED's with the power supply externally from the arduino and then run your arduino mega in parallel to the power supply and just connect the digital pin, Pretty sure the mega cant handle the current or output the 12v
Correct! The Arduino I/O pins are 5v, and rated for 40mA (0.04 Amps) maximum. They are "signal" or "data" lines and they can't directly power anything other than one or two regular little LEDs. (With the right circuitry, they can control thousands of Watts, but they can't directly provide power.)
To power an LED strip you can use a [u]MOPSFET driver[/u]. The schematic shows a motor, but it will also work with an LED strip. Since LEDs are non-inductive, you can leave-out D1.
You'll need one driver for each separately-controlled segment. i.e. A single-digit 7-segment display needs 7 drivers and 7 I/O pins. You may be able to find a multi-port driver chip, but make sure it can handle the required current. (You notes say 5A 6A, but I assume that's for the full 5-Meters.)
And of course, your 12V power supply has to supply all of the required current.
...I recommend that you build one driver circuit and test one LED strip/segment (maybe with the Blink Example) before you build the whole thing.
If segment current draw is less than 150mA, then you can use a TPIC6B595 shift register (per 7-segments). Shift registers only use three pins of the Arduino, so an Uno also could work. Example of a large digit driver here. Leo..
Or TPIC6595 for 250mA. TPIC6A595 for 350mA
Or my board with 32 N-channel MOSFET transistors for higher current.
http://www.crossroadsfencing.com/BobuinoRev17/#MOSFET
Confusing/different datasheets.
The C version is actually lower than the B version.
Look at the max ratings for “all outputs on”.
The B version could drive segments with 21 LEDs (140mA).
Assuming each “section of three” of the 12volt red strip is using 20mA.
Leo…
DVDdoug:
To power an LED strip you can use a [u]MOPSFET driver[/u].
A MOPSFET, of course, is a transistor made from a Mopion crystal lattice, grown in a bucket and doped with wringers. When a voltage is applied to the Janitor, the wringers activate and swish the Mopion charge carriers, from the floor, to the sink, thus acting as a switch. It’s a fairly slow transistor, but functions very well in damp and dank environments.
Just kidding ;D
I believe the DVDdoug meant to write MOSFET.
Thanks you guys ! I have learn a lot of things. I am building my first digit display with red strips led but something is wrong.. My leds seems not to bright enough and I dont know why ! No matter resistor I put, my leds bright same way. My power supply is 12v 2A (I tried with 12v 6A and that's same result). I pluged my volmeter to check if it delivers 12v. My transistor is TIP120 I am using Blink example to make shine my leds
Look at my leds closer(yes they are shining.. a little bit) : 
What can i do ? Have a good day ! :)
KeketteStyle: My LEDs seems not to bright enough and I dont know why ! No matter resistor I put, my leds bright same way. My power supply is 12v 2A (I tried with 12v 6A and that's same result). I plugged my voltmeter to check if it delivers 12v.
Good start.
KeketteStyle: My transistor is TIP120
Poor choice, really need a proper FET. Should sort-of work though.
KeketteStyle: I am using Blink example to make shine my LEDs
Are you really? Are you setting the (correct) output pin as pinMode(pin, OUTPUT); in setup?
Is the strip bright when you connect it directly to that 12volt supply.
You could just test that by shorting collector to emitter with the tip of a screwdriver.
Leo…
I solved my problem. I put a wire between emitter to negative pole on my breadboard (from power supply) then a wire between negative pole to gnd (from arduino). Now it's shinning like las vegas :D
How many leds can shine with my TIP120 ? Which transistor should I have ? I need one TIP120 per digit ? (7 segments = 42 Leds) So I need 5 TIP120 to build my scoreBoard. then 5 * 42Leds = 210 Leds. Can i make shine these all leds ?
KeketteStyle: I solved my problem. I put a wire between emitter to negative pole on my breadboard (from power supply) then a wire between negative pole to gnd (from Arduino). Now it's shinning like Las Vegas :D
So there was a connection missing which was not obvious to us since your photograph was taken in darkness instead of daylight and showed only a small section of your arrangement.
KeketteStyle: How many LEDs can shine with my TIP120 ? Which transistor should I have ? I need one TIP120 per digit ? (7 segments = 42 Leds) So I need 5 TIP120 to build my scoreBoard. then 5 * 42Leds = 210 Leds. Can I make shine these all LEDs ?
Do you not need a transistor for each segment? So 35 transistors.
You haven't specified the LED segments adequately. How much current do they draw? For the 6 LED strips you illustrate, I gather they draw 60 mA per three LED section at 12 V, so 120 mA for two sections. As Wawa and CrossRoads have explained, a TPIC6B595 can drive eight such segments so you would need five of them for five digits. These are serial shift registers which chain from one to the next, so you only need three Arduino pins to drive them, a Nano would do the job perfectly, a Mega 2560 is quite inappropriate.
Seven TIP120 transistors per digit, one for each segment.
Five digits is 5*7= 35 transistors, and 35 Arduino pins.
Read post#3 again. Leo..
Nice thanks you a lot for your answers :) My project is growing ! I did my first digit and I handle it by remote control. However, my IR range is barely 1 meter.. How can I increase that ? I have to increase emitter or receiver ? both ? How does it works on my tv ? (on my tv, my remote control have a strong signal)
I have first components from beginner arduino kit
Have a good day :)
KeketteStyle: ...my IR range is barely 1 meter.. How can I increase that ? I have to increase emitter or receiver ? both ? How does it works on my tv ? (on my tv, my remote control have a strong signal)
If you rolled your own IR transmitter, then perhaps you're not driving the IR LED with a high enough current. OR, the IR LED you chose isn't bright enough. TV remotes drive their LED(s) to the absolute max -- probably on the order of 50mA [depends on the LED]. This is possible because the LED is being pulsed [i.e. not on all the time]. Most datasheets indicate a pulsed current rating. That's the one you need to use.
Hello guys, I am beginner at electronics.. I am building a scoreboard for my baseball team and i would like to connect my 7 segments to a shift register.
I success to use shift register and make shine 8 leds one by one. My circuit is :
(https://www.instructables.com/id/8-LED-Knightrider-Using-Shift-Registers-With-Ardui/).
theses leds are on 5v
Now I want to replace these 8 leds by my 7 segments (12v and 1 segment = 6 leds).
So I connect my 12v jack on arduino and I replace pin 5v to Vin. Then I add transistor to connect my segment but it doesn't work... My circuit : 
(on this picture,my jack is off, but trust me, i tried !)
I am using the same arduino code as above.
Where is my mistake ?
Use a shift register that can switch 12volt/150mA. Like the TPIC6B595 (ebay).
This page might interrest you. Leo..
ouch price is expensive ! I saw some projects using shift register 74HC595 to their score board (also with 12v leds). https://www.instructables.com/id/Remote-Controlled-Arduino-Scoreboard-using-LED-Str/
Can you help me to use this shift register (74HC595) with my leds 12v ??
KeketteStyle: ouch price is expensive !
I saw some projects using shift register 74HC595 to their score board (also with 12v leds). Can you help me to use this shift register (74HC595) with my leds 12v ??
Do you call $0.50 for a TPIC6B595 expensive?
Sure, you can use the 74HC595, but you have to add a transistor to each output. That could get messy and expensive. Leo..
I talked about SparkFun Large Digit Driver :p
I got already 74HC595 and transistor TIP120. With this shift register, I have to use 5v for shift register and 12v for leds ?