[SOLVED] I adapted a scematic, PROBLEM: I'm a noob

Hi! I want to make a sound responsive led strip, and I'll add a lot of other functions :) This is the original schematic (found on the internet): OLD SCHEMATIC And this is how I adapted it: NEW SCHEMATIC I added a power source: I don't want to put 12V on my Arduino to prevent heating and to make it easier to know what adapter I have to buy :) I also might a function to light the leds on data received by a computer via USB. I also changed the MOSFET's, they weren't logic level ones, to IRL3705N.

So is this schematic ok? I don't know wether that common ground is good... Thanks for your help!! Bram

Looks fine to me.

Thanks Grumpy_Mike! When it arrives I'll give it a try. I just don't want to mess my stuff up, that's why I ask a pro to verify :) (+karma)

It's ok, [u]always[/u] use common ground with different voltages.

Thanks Kong!
This is all quite new to me, a month ago I’d not have known what a common ground was. So it’s quite a guess for to apply it.
So thanks for the tip, I will temember it! :slight_smile:

Everything just arrived, and the scematic does indeed work! JIPPEEEEE! 8)

Well done. It is a great feeling when something works.

I may be reading it wrong, but I see the external 5V supply connected to the 5V pin instead of the Vin pin - that's not good for the lifespan of the Arduino.

kd7eir is right, The 5v power supply is connected to the 5v pin instead of the Vin pin, that can damage the arduino. I am sure it is just a mistake but just to make sure... ;)

kd7eir:
I may be reading it wrong, but I see the external 5V supply connected to the 5V pin instead of the Vin pin - that’s not good for the lifespan of the Arduino.

If it is in fact, a 5V regulated supply, that is precisely where you would connect it - to the 5V Vcc pin.

If you connect 5V to Vin, the regulator will not regulate it, but you will lose a significant voltage drop as it attempts to do so.

If the voltage is regulated to EXACTLY 5V that is true, but I would not trust any power supply that did not cost several times the price of the Arduino to maintain that EXACT 5V level.

kd7eir:
If the voltage is regulated to EXACTLY 5V that is true, but I would not trust any power supply that did not cost several times the price of the Arduino to maintain that EXACT 5V level.

Well, the 328 is rated 6V “absolute maximum” as I recall, so it is not really that critical. 5.5V should be a safe excursion.

I do however think that if you value your circuits, a 5V (switchmode) supply should have a crowbar.

My concern is the vast number of power supplies that claim to be "regulated" but in fact put out far in excess of their "regulated" voltage.

Obviously only the OP knows the quality of his power supply.