Connect my led strips (12v) to arduino

Paul__B: If you connect anything more than a few TPIC6B595s to the 5 V however, it will likely overheat and shut down intermittently. It would be better to use one of the switchmode "buck" regulators readily available to feed proper 5 V to the Arduino via its 5 V terminal.

I'm probably misreading this, but if you are saying that the 5V regulator on the Arduino board, can't drive more than a few TPIC6?595s? If so, consider that [from the datasheet] ICC MAX is 5mA and TYP 0.5mA, then, at a conservative 100mA max from the Arduino regulator, that's 100mA/5mA = 20, worst case. In other words, at least 20 TPIC6?595s can be powered by the Arduino 5V regulator. And, possibly even more, since the regulator current limits at 500mA. So, it would be a matter of heat caused by dissipation due to drop out voltage. [Unless we're talking about something other than an UNO -- wasn't able to determine, for sure]

Paul__B: See reply #11. Given you are using only two of the three LED sections which will draw just 120 mA for each segment, the TPIC6B595 is the perfect solution. Rubbish!

Why "Rubbish"? According to the datasheet, even if ALL of the Drains are sinking the Absolute Maximum 150mA continuously, is acceptable for less than "extended periods". So, 120mA on one or more Drains, even simultaneously should be just fine if intermittent enough. 90mA is the Recommended Nominal. So, does "Rubbish" refer to this?

ReverseEMF: So, does "Rubbish" refer to this?

Read more closely - and then read CrossRoads' answer. :roll_eyes:

Hello guys ! @ReverseEMF, you're giving too much information than I can't understand :D. I repeat, I am a beginner.

Good news, my scoreboard project is growing : |375x500

I have build first 2 digits but I noticied something.. More leds segments are ON and less leds shine. How can I give same voltage/Intensity to each led segment ?

This is my circuit :

I am using 1 ULN2803 per digit and I connected together 2 shift registers. Someone can explain me how to make brighter my leds ?

thanks you guys. I wish you good holidays ! :)

You need to check your 12 V supply voltage for the different combinations of LEDs.

Check the common ground connection to Arduino, 74HC595s, ULN2803s and the 12 V supply.

Iā€™m not on holidays any time soon.

KeketteStyle: I have build first 2 digits but I noticied something.. More leds segments are ON and less leds shine. How can I give same voltage/Intensity to each led segment ?

Sounds like you have too few resistors in your design. Each LED, or series of LEDs, needs its own current limiting resistor.

Ok Paul I will check I Come back :)

I have 0 resistors :o that s mean is bad ?? It can explain performance of my leds?

What's the current of a LED row, and the power of your 12V supply?

OP is using LED strips, with resistors on the strip. So no extra resistors needed. Leo..

DrDiettrich: What's the current of a LED row, and the power of your 12V supply?

See first post.

And answer #7.

6 LEDs per row.
Someone have a good Idea ? :slight_smile:

I still think that the supply voltage is important. Check the voltage when only few segments are lit, and when more are lit. Fractions of a volt may make a difference, i.e. a switching transistor already may cause problems. I'd try to increase the supply voltage to 14V or 15V, if the strips support that.

If I read you correctly, you're saying that in some cases, when more than one LED strip is powered, all of the LEDs in those strips, dim down, as if the addition of one or more strips is loading something down...is that right?

And, assuming I got that right, here are a few possibilities:

  • Upon close examination of the photo you supplied [https://zupimages.net/up/18/31/klvm.jpg], I see what appears to be fat, foil ribbons running to the various LED strips. In a few cases it looks like a couple of LED strips are "daisy-chained" together, In other words, a foil ribbon goes to one LED strip, then from the other end of that LED strip extends another foil ribbon until it reaches yet another LED strip.

If that's the case, and if these are power lines, then what could be happening is, the daisy chained path may be presenting a high enough series resistance as to inject a significant voltage drop, thus dimming the LEDs. Because of the fairly sharp LED Forward Voltage curve [i.e. exponential relationship between forward voltage and current], it doesn't take much of a voltage drop to cause a significant dimming.

You really should run separate power lines to each LED strip, all running back to a common point, as near to the power source as possible [or if that's not practical, then you need a hefty "power buss" that those lines can run to]. A power buss is merely a conductor with sufficient bulk to minimize voltage loss at the highest in-circuit current levels [which is, usually, a combination {or adding} of all the simultaneous currents that will flow through the buss]. - Another possibility is the overloading of the power source. If ALL of the LEDs are dimming at once, then that points to the Power Source as the problem [or it could be a high resistance point in a common power line--see #3]. If the power source voltage is dipping because too much current is being drawn [or because the power source is failing], then that will cause the LEDs to dim. Once again, it doesn't take much of a voltage dip to dim an LED. - Similar to #2, if there is a common power line, or common connection point from the power source, this might be the source of the dimming. A way to test for this is to get a small[ish] gauge wire [i.e. a fat wire] and, when you see the dimming [of the LED(s)], jumper across all potential problem sources--i.e. provide a temporary "good connection". If the LEDs brighten up, you're closing in on the culprit. Process of elimination will guide you to the weak link. If any of the LED current is traveling down any of the buss lines on that protoboard, then THAT very likely could be the source of the dimming. - The ULN2803s have internal current "clamp" to the tune of 500mA on each output, and an overall limit of 2.5A. If more current than these limits is occurring, that would cause a dimming. So, a current inventory might be in order. - Another possible source of dimming could be in your code [I don't see a listing anywhere]. If there is any sort of multiplexing or PWM involved, and if the pattern of this changes, such that the duty-cycle is different when the dimming occurs, then that's your problem. This could occur if, say, a code loop executes faster when only one LED strip is lit, but runs slower when two, or more, are lit. Something like that. This is unlikely, but I mentioned it for completeness ;)

Thnaks a lot Reverse :) My power supply was dying.. I changed it and now it works perfectly ! I'll send some pictures when I finish my board. See you :)

Hola, I have some problems :(

I was running my scoreboard, after 1 hours, my arduino mega fried.. (saw sparks on ship in middle board). My arduino mega was very hot ! Why it fried ? On my scoreboard I have : - power supply 12v 2A (to connect my Leds) - 7x2 segments (=2 digits). Each digit = 6 Leds. Each segment runs on 12v - Each digit are connected to ULN2803 then to shift register - I have resistors only on my segment leds

Maybe I should use 9v ? Arduino uno is better than arduino mega ? I forgot some resistors ? Tell me please :)

See you guys !

Based on your limited "schematic" [more like a block diagram], things seem to be arranged correctly, so:

  • Something happened related to something obscured by lack of information.
  • Something just, plain-and-simple, failed on the Mega (it should be able to handle 12V just fine, and it doesn't look like [again, based on sketchy information] anything is drawing excessive current from the Mega)
  • Maybe water splashed on the Mega -- that would do it -- especially salt water!

Sparks on ship or strip?

Replace the sparkling item and continue.

Sparks on my arduino mega :( here :

No water, It was running close of me then I saw that.

It works well for 1 hour and then... boom

Maybe I should reduce voltage ? (my arduino is burning, that's normal ?)

You could do a quality check on all items, including power supplies, but I fear that you can't do that :-(

Why aren't you using TPIC6B595 for the segments? One shift register per digit, vs 2 chips. No problem driving 9 LED strips either.

Here's a board I offer that will drive 12 digits, driving 3 and 6 LED strips

https://www.youtube.com/watch?v=6HZ0Mr51jUY

|500x479

http://www.crossroadsfencing.com/BobuinoRev17/

CrossRoad, Tpic6b595 Can replace uln2803 + 74hc595 ?

This is my circuit : |249x500

What do you think ?